Next Article in Journal
Detection of Nitrate-Reducing/Denitrifying Bacteria from Contaminated and Uncontaminated Tallgrass Prairie Soil: Limitations of PCR Primers
Previous Article in Journal
A Controlled, Retrospective, Single-Center Study to Evaluate the Role of a Probiotic Mixture Administered during Pregnancy in Reducing Streptococcus Agalactiae Swab Positivity and the Frequency of Premature Rupture of Amniochorionic Membranes
Previous Article in Special Issue
Microeukaryotes Associated with Freshwater Mussels in Rivers of the Southeastern United States
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Microorganisms
Volume 12
Issue 10
10.3390/microorganisms12101980
microorganisms-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Effect of Dietary Astragalus polysaccharides (APS) on the Growth Performance, Antioxidant Responses, Immunological Parameters, and Intestinal Microbiota of Coral Trout (Plectropomus leopardus)

by
Xiaoqi Hao
1,2,
Heizhao Lin
1,3,
Ziyang Lin
1,
Keng Yang
1,
Jing Hu
1,
Zhenhua Ma
1,4 and
Wei Yu
1,3,4,*
1
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, China
2
Ocean College, Hebei Agricultural University, Qinhuangdao 066003, China
3
Shenzhen Base of South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shenzhen 518121, China
4
Key Laboratory of Efficient Utilization and Processing of Marine Fishery Resources of Hainan Province, Sanya Tropical Fisheries Research Institute, Sanya 572426, China
*
Author to whom correspondence should be addressed.
Microorganisms 2024, 12(10), 1980; https://doi.org/10.3390/microorganisms12101980
Submission received: 5 September 2024 / Revised: 26 September 2024 / Accepted: 26 September 2024 / Published: 30 September 2024
(This article belongs to the Special Issue Aquatic Microorganisms and Their Application in Aquaculture)
Browse Figures
Versions Notes

Abstract

:
The potential effects of Astragalus polysaccharides (APS) were evaluated in coral trout (Plectropomus leopardus). Five APS levels (0%, 0.05%, 0.10%, 0.15%, and 0.20%) were added to the diet of coral trout, and a 56-day growth trial (initial weight 18.62 ± 0.05 g) was conducted. Dietary APS enhanced growth performance, with the highest improvement observed in fish fed the 0.15% APS diet. This concentration also enhanced the antioxidant capacity and immunomodulation of the fish by regulating the expression of genes associated with antioxidant enzymes and immune responses. Intestinal microbiota analysis revealed that APS supplementation significantly increased the Chao1 index and relative abundance of beneficial bacteria (Firmicutes and Bacillus). A high level of APS (0.20%) did not provide additional benefits for growth and health compared to a moderate level (0.15%). These findings indicate that an optimal APS dose promotes growth, enhances antioxidant activity, supports immune function, and improves intestinal microbiota in coral trout. Based on a cubic regression analysis of the specific growth rate, the optimal APS level for the maximal growth of coral trout was determined to be 0.1455%.

1. Introduction

The coral trout, Plectropomus leopardus, is a marine creature with high economic and ornamental value in China and is prized for its delicious meat and rich nutritional content [1,2]. As high-density intensive farming becomes more common, cultivated coral trout have become more susceptible to diseases, in contrast to their wild counterparts [3,4]. Although antibiotics are frequently employed to treat these infections, their excessive use can result in environmental pollution and the development of antibiotic-resistant bacteria [5]. To address these concerns, aquaculture is gradually phasing out harmful traditional treatments [6]. Therefore, developing environmentally friendly and nutritionally balanced feed ingredients with immunomodulatory properties is crucial.
Astragalus polysaccharides (APS) are natural active compounds derived from Astragalus, a traditional herbal medicine that has been used as an immune enhancer in China for nearly 2000 years [7,8]. Over the past few decades, dietary supplementation with APS has been widely reported to improve the nutritional status and physiological conditions of mammals, livestock, and humans. [7,9,10,11,12,13]. Recent studies have also reported that APS can enhance the growth performance, antioxidant capacity, and immune function of aquatic species, such as turbot (Scophthalmus maximus) [14], largemouth bass (Micropterus salmoides) [15], white shrimp (Litopenaeus vannamei) [16], Furong crucian carp (Furong carp♀ × red crucian carp♂) [17], crucian carp (Carassius auratus) [18], Chinese mitten crab (Eriocheir sinensis) [19], and pearl gentian grouper (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatus) [20]. Supplementation with APS in diets significantly increased growth (weight gain, specific growth rate (SGR), and feed conversion ratio) and immune (phagocytic activity, respiratory burst activity, plasma lysozyme (LZ), and bactericidal activity) parameters in Nile tilapia (Oreochromis niloticus) [21]. Additionally, dietary APS markedly increased the superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities in red claw crayfish (Cherax quadricarinatus) [22] and northern snakehead (Channa argus) [23], while reducing the malondialdehyde (MDA) levels. In addition to enhancing growth, antioxidant capacity, and immunity, APS also influences the digestive systems of aquatic animals. Studies have reported that dietary APS positively influences the activity of digestive enzymes and intestinal structure in grass carp (Ctenopharyngodon idellus) [24], large yellow croaker (Larimichthys crocea) [7], and Nile tilapia [21]. Furthermore, APS can enhance growth by improving intestinal health and modulating gut microbiota [25].
Previous investigations have primarily focused on the health benefits of APS for fish, and the potential negative outcomes of its overuse are underexplored [26]. Moreover, its effects on coral trout growth have not been reported. In this study, we assessed the effects of APS on growth, antioxidant status, immunological parameters, intestinal morphology, digestive enzyme activity and flora, liver antioxidant and immune-related enzyme activities, and gene expression in coral trout. We also determined the optimal APS dosage and explored the negative consequences of exceeding this amount. These results are expected to provide a theoretical basis for dietary APS supplementation in coral trout.

2. Materials and Methods

2.1. Materials and Experimental Diets

APS, with a purity of 91.5%, was obtained from Beijing Shoutianzhixin Technology Co., Ltd. (Beijing, China). Following the procedure outlined by Yu et al. [27], five diets were prepared with APS contents of 0%, 0.05%, 0.10%, 0.15%, and 0.20%; details are provided in Table S1. Detailed operational procedures are outlined in Supplementary Materials (Method S1).

2.2. Fish Management

The aquaculture setup was a recirculating aquaculture system (RAS), which included 15 tanks of 1.0 m³ each. Three hundred fish were randomly dispersed across the tanks after acclimatization, with three replicates used for each diet. For 8 weeks, each experimental diet was hand-administered twice a day (at 8:30 and 16:30) until the fish reached apparent satiation. Water conditions were maintained at a temperature of 28.00 ± 2.00 °C, pH 7.15 ± 0.15, dissolved oxygen >7.00 mg/L, and ammonia nitrogen <0.05 mg/L.

2.3. Sampling

Fish were fasted 24 h before sampling and anesthetized using eugenol (50 mg/L; Jian Huashuo Spice Oil Co., Ltd., Jian, China). The total quantity and weight of fish in each tank were recorded. The weight and length of three fish from each cage were measured to calculate the morphology indices, and six fish were randomly selected from each replicate for sampling. Subsequently, liver samples were taken from six fish and preserved at −80 °C for gene expression analysis. The remaining liver tissues were also stored at −80 °C for enzyme activity analysis. The intact intestines of the three fish were removed for gut microbiome analysis. Midgut samples from three additional fish were obtained and soaked in 4% paraformaldehyde solution (Biosharp, Guangzhou, China) for histological tests, while the remaining intestinal tissues were stored at −80 °C for enzyme activity analysis.

2.4. Calculations

The weight gain rate (WGR, %), specific growth rate (SGR, %/day), survival rate (SR, %), viscerosomatic index (VSI, %), hepatosomatic index (HSI, %), and condition factor (CF, g/cm3) were determined using the following equations:
WGR = 100 × (final weight (g) − initial weight (g))/(initial weight (g))
SGR = 100 × (ln (final weight (g)) − ln (initial weight (g)))/(days)
SR = 100 × (final fish number)/(initial fish number)
VSI = 100 × (visceral weight (g))/(body weight (g))
HSI = 100 × (hepatic weight (g))/(body weight (g))
CF = 100 × (body weight (g))/(body length (cm))3

2.5. Proximate Composition

Diet composition was determined as previously described [28]. Moisture content was determined in the oven (105 °C) until constant weight. Crude protein and crude lipid contents were determined using the Kjeldahl nitrogen and Soxhlet extractions, respectively. The diets were burned in a muffle furnace (550 °C) for the determination of the ash contents.

2.6. Enzyme Activity Analysis

Enzyme activities related to digestion, antioxidant defenses, and immune response were measured using commercial assay kits (Jiancheng, Ltd., Nanjing, China) according to the manufacturer’s guidelines and formulas included with the kits. Detailed operational procedures are outlined in Method S2.

2.7. Real-Time Quantitative PCR Assay

Table S2 lists the specific primers of target genes and the reference gene (GAPDH). The qPCR reaction was conducted using the SYBR Green Pro Taq HS Premix kit (Accurate Biotechnology Co., Ltd., Changsha, China). Detailed operational procedures are outlined in Method S3. Gene expression levels were measured following Livak and Schmittgen’s approach [29].

2.8. Mid-Gut Histological Observation

Intestinal sections were stained with H&E and photographed. Morphological parameters were determined using CaseViewer 2.4 software, as described by Xie et al. [30].

2.9. Gut Microflora

Based on the analysis of growth performance results, 0.15% APS was identified as the optimal level for coral trout in this study. Gut microbiota effects were analyzed by selecting samples from the control group and the groups with the highest SGR and WGR groups. Amplification of the hypervariable 16S rRNA gene V3-V4 regions was performed using the specific 341F (CCTAYGGGRBGCASCAG) and 806R (GGACTACNNGGGTATCTAAT) primers with unique barcodes for each sample. Purified amplification products were linked to sequencing junctions, and sequencing libraries were created. Sequencing was performed on an Illumina platform. Raw data underwent splicing, filtering, and chimera removal to generate the final effective dataset for evaluation of the characteristics of intestinal microbiota. DNA amplification and sequencing were conducted by Beijing Novogene Co., Ltd. (Beijing, China).

2.10. Statistical Analysis

Data were presented as mean ± standard error (mean ± SE). Statistical significance was set at p < 0.05. Statistical analysis was performed using SPSS 27.0 software employing a one-way ANOVA to compare datasets among groups. Duncan’s and LSD multiple comparison tests were utilized to evaluate significant differences between and within groups. The cubic regression model was applied to predict the optimal APS level for the SGR of coral trout, which was identified as the most effective model because of its low residual sum of squares and high goodness-of-fit (R2) values.

3. Results

3.1. Growth Performance

As APS levels increased from 0.10% to 0.15%, the final body weight (FBW), WGR, and SGR in coral trout improved compared to the control (p < 0.05) (Table 1). However, the 0.20% APS group exhibited significantly lower FBW, WGR, and SGR than the 0.15% APS group (p < 0.05). SR, VSI, HSI, and CF were not significantly affected by different levels of APS supplementation (p > 0.05). The optimal level of dietary APS in the coral trout diet, based on SGR, was determined to be 0.1455% (Figure 1).

3.2. Digestive Enzyme Activities

Diets containing 0.10% to 0.15% APS significantly increased α-amylase and lipase activities compared to other diets (p < 0.05) (Table 2). No effect on chymotrypsin activity was observed owing to the dietary APS modifications (p > 0.05).

3.3. Gut Morphology

Midgut villus length and muscle thickness were significantly increased in groups receiving 0.10%–0.20% APS (p < 0.05) compared to the control. Additionally, H&E-stained intestinal sections revealed no significant morphological alterations in the intestinal tissues of the test fish that received diets containing varying APS concentrations (Figure 2).

3.4. Liver Antioxidant Capacity

Superoxide dismutase (SOD) activity in the 0.10% to 0.15% APS groups and catalase (CAT) activity in the 0.15% APS group were significantly higher than those in the control group (p < 0.05) (Table 3). GSH-Px activity and total antioxidant capacity (T-AOC) peaked in the 0.15% APS group, showing significantly higher levels in the control and 0.20% APS groups (p < 0.05). Additionally, the MDA levels decreased significantly as the dietary APS dose increased (p < 0.05).

3.5. Liver Immune Function

Table 4 shows that alkaline phosphatase (AKP) activity, complement 4 (C4), and immunoglobulin M (IgM) levels were significantly higher in the 0.15% APS group compared to the control group (p < 0.05). The 0.10% to 0.20% APS groups exhibited higher acid phosphatase (ACP) and LZ activities compared to the control group (p < 0.05). The complement 3 (C3) levels were significantly increased in the 0.10% to 0.15% APS groups relative to both the control and 0.20% APS groups (p < 0.05).

3.6. Relative mRNA Expression in the Liver

Figure 3 shows the antioxidant and immune-related gene expression in coral trout across the different APS groups. The highest relative expression levels of SOD-2, GSH-Px1a, and ACP6 were observed in the APS-treated groups, with significant differences from the control (p < 0.05). The 0.15% APS group exhibited significantly higher expression levels of these genes, along with AKP, C3, C4-b, and LZ-c, compared to the control and 0.20% APS groups (p < 0.05). Moreover, the expression levels of SOD-2, GSH-Px1a, ACP6, AKP, C4-b, and LZ-c were significantly increased in the 0.10% and 0.15% APS groups compared to the control (p < 0.05).

3.7. Gut Microbiota

3.7.1. Intestine Microbial Diversity

Figure 4A shows the alpha-diversity indices, including Chao 1, Shannon, and Simpson. The Chao1 index of the 0.15% APS group was considerably higher compared to the control group (p < 0.05). No significant differences in the Shannon and Simpson indices were observed (p > 0.05). The rarefaction curves of species in the intestines of the two groups indicated that the sequencing depth was sufficient (Figure 4B). A principal co-ordinates analysis (PCoA) plot based on a weighted UniFrac distance matrix was executed to show a clear separation between intestinal microbial communities in coral trout fed with APS and control diets, indicating significant compositional differences (Figure 4C).

3.7.2. Intestine Microbial Composition

Figure 5 presents the relative abundance of intestinal flora, providing an overview of the microbial composition at both the phylum and genus levels. According to the taxonomic results at the phylum level (Figure 5A,B, top 10), in the control group, Proteobacteria was the most abundant, followed by Spirochaetota, Firmicutes, and Actinobacteriota, at 58.95%, 27.96%, 3.50%, and 2.92%, respectively. Conversely, in the 0.15% APS group, Firmicutes was the predominant phylum, followed by Proteobacteria, Actinobacteriota, and Cyanobacteria (46.58%, 42.04%, 3.51%, and 2.46%, respectively). Based on the taxonomic results at the genus level (Figure 5C,D, top 10), Brevinema and Motiliproteus (33.11% and 29.35%, respectively) were more dominant in the control group, whereas Photobacterium, Bacillus, and Fictibacillus (31.67%, 17.18%, and 15.95%, respectively) were more abundant in the 0.15% APS group.

4. Discussion

The current study demonstrates that dietary supplementation with 0.15% APS resulted in the highest WGR and SGR in coral trout, suggesting that APS positively influences coral trout growth. These findings align with previous research on Nile tilapia [21] and large yellow croaker [7]. The growth-promoting effects of APS on coral trout can be attributed to two key factors. First, the appropriate APS dosage stimulated increased α-amylase and lipase activities in coral trout. Digestive enzyme activity is often considered an indirect indicator of fish growth [31]. In the present study, we identified a positive correlation between digestive enzyme activity and growth markers (WGR and SGR), potentially explaining the growth-promoting effects of APS on coral trout. Similarly, studies on largemouth bass (Micropterus salmoides) [32], large yellow croaker [7], crucian carp [18], giant freshwater prawn (Macrobrachium rosenbergii) [33], and spotted sea bass (Lateolabrax maculatus) [34] demonstrated that dietary APS supplementation significantly enhanced digestive enzyme activities. Additionally, intestinal morphological characteristics are essential for evaluating the digestive capacity and intestinal health of fish [35]. Supplementation with 0.1% to 0.15% APS has been shown to increase intestinal villus length and muscle thickness, which could also explain the accelerated growth of coral trout. This result is consistent with the findings of Liu et al. [7] and Duan et al. [32], who observed similar effects in large yellow croaker and largemouth bass, respectively. However, a high dose of APS (0.20%) did not further improve WGR and SGR compared to a moderate dose (0.15%), indicating potential immunosuppressive effects at higher doses, which may suppress growth performance [18,26]. In this study, the optimal APS dosage (0.1455%) was established according to the SGR of coral trout. Studies with similar results have indicated that the growth of aquatic animals initially increases with enhanced APS supplementation but eventually plateaus and declines [7,17,19]. Despite these findings, the role of APS in enhancing the growth of aquatic animals is not fully understood. Previous studies have shown that feeding APS to sea cucumbers (Apostichopus japonicus) [9] and red claw crayfish [22] did not enhance their growth. These studies demonstrate that the growth impact of APS in aquatic animals was contingent on the species, dosage, and experimental conditions. Thus, cultivation strategies that are carefully adapted to the needs of each fish species should be developed to enhance growth performance.
APS is also considered a potent antioxidant, potentially effective in boosting antioxidant enzyme activity and reducing oxidative stress in aquatic species [26,36]. MDA is a major and most extensively studied biomarker of lipid peroxidation [7,37]. In this study, the antioxidant capacity of coral trout was notably improved with APS supplementation, as evidenced by increased activities of SOD, CAT, GSH-Px, and T-AOC, along with a decrease in MDA levels, particularly in the 0.15% APS group. Earlier research has demonstrated similar outcomes, demonstrating that APS supplementation could boost SOD, CAT, and T-AOC activities in large yellow croaker [7] and largemouth bass [32], and significantly reducing MDA content. Yu et al. [26] also observed that adding APS to the diet of Asian seabass (Lates calcarifer) significantly enhanced SOD, CAT, and GSH-Px activities, increased T-AOC levels, and reduced MDA contents, though the maximum dose of 0.20% APS did not yield the highest total antioxidant capacity. In line with their findings, our study found that when the APS dose was increased to 0.2%, the GSH-Px activity and T-AOC contents in the liver were significantly lower than those observed in the 0.15% group, suggesting that higher levels of APS may not provide additional antioxidant benefits for coral trout.
ACP and AKP are crucial for enhancing fish resistance to microbial pathogens [38]. Previous research by Zhang et al. [39] on large yellow croaker (Larimichthys crocea) and by Song et al. [9] on sea cucumber demonstrated that APS could enhance the activities of non-specific immune enzymes, such as ACP and AKP. C3, C4, IgM, and LZ serve as key indicators of fish immunity [40]. APS significantly enhanced the aforementioned immunological parameters in C. argus [23] and L. calcarifer [26]. Consistent with these findings, the present study found that APS significantly boosted ACP, AKP, and LZ activity along with C3, C4, and IgM levels in coral trout, showing the highest levels in the 0.15% APS group. However, when the APS dose was increased to 0.2%, the C3, C4, and IgM levels significantly dropped compared with those observed in the 0.15% group. Similarly, Pu et al. [16] and Wu [18] found that high levels of Astragalus membranaceus polysaccharide (AMP) did not further enhance the innate immune response in white shrimp and crucian carp compared to moderate AMP levels. These results indicated that coral trout do not require higher APS levels.
To better understand the effects of APS supplementation on coral trout, we analyzed mRNA levels in the liver and found that diets containing 0.15% APS significantly upregulated the expression of SOD-1, SOD-2, CAT, GSH-Px1a, ACP6, AKP, LZ-c, IgM, C3, and C4-b. While increased mRNA levels partially elevated enzyme activity, the changes in enzyme activity did not always align with mRNA expression [41]. Our study on coral trout revealed that only the liver levels of CAT, GSH-Px, ACP, LZ, C3, and C4 were consistent with the trends in mRNA expression. In groups fed 0.2% APS, the expression levels of SOD-2, GSH-Px1a, ACP6, AKP, C3, C4-b, and LZ-c were notably lower than those in groups fed with 0.15% APS. This alteration corresponded to the trend observed in enzyme activity changes in the liver, implying that an excess of APS reduced its effectiveness.
Intestinal microbes are crucial for nutrient digestion, absorption, and the overall health of fish [42]. Research has shown that herbal medicines can stimulate appetite and influence microbial communities within animals, with greater diversity in the intestinal microbiota leading to higher functional stability [8,43,44]. We found that the APS-fed groups had higher diversity indices (Chao1, Shannon, and Simpson) than the control group, suggesting that APS supplementation supports intestinal homeostasis. Additionally, PCoA analysis with weighted UniFrac distances and differences in intestinal bacterial composition in the control and APS groups indicated that dietary APS modified the intestinal microbiota in coral trout. Therefore, a certain amount of APS enhances intestinal health.
APS can benefit gut microbial communities by enhancing the growth of beneficial bacteria while reducing the risk of bacterial and viral infections [19,24]. At the phylum level, most species within Proteobacteria and Spirochaetota act as conditional pathogens [44,45]. The study results indicated that the relative abundances of Proteobacteria and Spirochaetota in the APS group were lower than those in the control group, suggesting that dietary APS supplementation reduces the risk of intestinal diseases in fish. Conversely, the abundance of Firmicutes, which play a critical role in the hydrolysis of maltose and trehalose, increased under the APS diet [46]. Firmicutes species are linked to butyrate production, which is crucial for gut microbiota-immune system communication, prevents intestinal infections by inhibiting pathogen adhesion to aquatic surfaces, and stimulates the innate immune response [47,48,49]. The observed increase in Firmicutes and the decrease in Proteobacteria and Spirochaetota abundance suggest that APS supplementation can potentially enhance intestinal health by mitigating the risk of intestinal diseases in fish. The Bacillus genus is widely used as a probiotic in aquaculture due to its ability to promote gut health and inhibit pathogenic bacteria [43,50,51]. Brevinema, a potential pathogen in the Spirochaetota phylum, was found to decrease in abundance in pompano (Trachinotus ovatus) as glycerol monolaurate levels increased [52], consistent with our findings. At the genus level, APS supplementation boosted beneficial bacteria such as Bacillus in the intestines of coral trout while suppressing harmful bacteria such as Brevinema, thereby optimizing the gut microbial composition and structure. These results suggest that APS supplementation may have a favorable effect on the intestinal health of coral trout. However, there is a limitation in the present study in that the gut microbiome of slow-growing fish has not been analyzed. Studying both high-growth and slow-growing fish could reveal how APS impacts the gut microbiome across different growth rates. Future research should investigate how APS may influence the gut microbiome at varying growth rates.

5. Conclusions

This study demonstrates that adding 0.15% APS can improve the growth, antioxidant capacity, immune function, and intestinal health of coral trout. However, compared with a moderate level of APS (0.15%), a high level of APS (0.20%) did not improve the efficiency of APS on the growth and health of coral trout. Therefore, 0.15% APS was optimal for coral trout growth. Furthermore, cubic regression analysis determined that the optimal APS level for maximum coral trout growth was 0.1455%. The study findings offer fresh perspectives on the underlying mechanisms of APS use in coral trout feed.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/microorganisms12101980/s1, Table S1: Composition and proximate chemical analysis of the experimental diets (expressed as % dry matter); Table S2: Primers and amplification conditions used for quantitative real-time PCR in this study; Method S1: Diet preparation; Method S2: Enzyme activity analysis; Method S3: Gene expression analysis.

Author Contributions

Conceptualization, X.H. and W.Y.; methodology, X.H. and H.L.; software, H.L.; validation, W.Y. and H.L.; formal analysis, Z.L. and K.Y.; resources, J.H. and Z.M.; data curation, X.H.; writing—original draft preparation, X.H.; writing—review and editing, W.Y.; visualization, H.L. and Z.L.; supervision, K.Y., J.H. and Z.M.; funding acquisition, W.Y. and H.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Hainan Province Science and Technology Special Fund (ZDYF2022XDNY349), Central Public-interest Scientific Institution Basal Research Fund, South China Sea Fisheries Research Institute, CAFS (2024RC15), National Key Research and Development Program of China (2022YFD2400501), Hainan Provincial Natural Science Foundation of China (321QN0942), Key Laboratory of Efficient Utilization and Processing of Marine Fishery Resources of Hainan Province (KLEU-2023-7), Guangdong Provincial Rural Revitalization Strategy Special Funds for Seed Industry Revitalization Project (2022-SPY-02-003), the earmarked fund for HNARS (HNARS-03-Z02) and Central Public--interest Scientific Institution Basal Research Fund, CAFS (2023TD58).

Data Availability Statement

The original contributions presented in the study are included in the article/Supplementary Materials. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Yang, Y.; Wu, L.N.; Chen, J.F.; Wu, X.; Xia, J.H.; Meng, Z.N.; Liu, X.C.; Lin, H.R. Whole-genome sequencing of leopard coral grouper (Plectropomus leopardus) and exploration of regulation mechanism of skin color and adaptive evolution. Zool. Res. 2020, 41, 328–340. [Google Scholar] [CrossRef] [PubMed]
  2. Hao, R.; Zhu, X.; Tian, C.; Jiang, M.; Huang, Y.; Li, G.; Zhu, C. LncRNA–miRNA–mRNA ceRNA network of different body colors in Plectropomus leopardus. Front. Mar. Sci. 2023, 10, 1170762. [Google Scholar] [CrossRef]
  3. Hao, X.; Lin, Z.; Ma, Z.; Yang, Y.; Zhou, C.; Hu, J.; Yu, W.; Lin, H. Effect of Dietary β-Glucan on Growth Performance, Antioxidant Responses, and Immunological Parameters of Coral Trout (Plectropomus leopardus). Fishes 2024, 9, 298. [Google Scholar] [CrossRef]
  4. Yu, W.; Wen, G.; Lin, H.; Yang, Y.; Huang, X.; Zhou, C.; Zhang, Z.; Duan, Y.; Huang, Z.; Li, T. Effects of dietary Spirulina platensis on growth performance, hematological and serum biochemical parameters, hepatic antioxidant status, immune responses and disease resistance of Coral trout Plectropomus leopardus (Lacepede, 1802). Fish Shellfish Immunol. 2018, 74, 649–655. [Google Scholar] [CrossRef] [PubMed]
  5. Boti, V.; Toli, V.; Efthymiou, C.; Albanis, T. Screening of Commonly Used Antibiotics in Fresh and Saltwater Samples Impacted by Aquacultures: Analytical Methodology, Occurrence and Environmental Risk Assessment. Sustainability 2023, 15, 9199. [Google Scholar] [CrossRef]
  6. Lieke, T.; Meinelt, T.; Hoseinifar, S.H.; Pan, B.; Straus, D.L.; Steinberg, C.E.W. Sustainable aquaculture requires environmental-friendly treatment strategies for fish diseases. Rev. Aquac. 2019, 12, 943–965. [Google Scholar] [CrossRef]
  7. Liu, Y.; Miao, Y.; Xu, N.; Ding, T.; Cui, K.; Chen, Q.; Zhang, J.; Fang, W.; Mai, K.; Ai, Q. Effects of dietary Astragalus polysaccharides (APS) on survival, growth performance, activities of digestive enzyme, antioxidant responses and intestinal development of large yellow croaker (Larimichthys crocea) larvae. Aquaculture 2020, 517, 734752. [Google Scholar] [CrossRef]
  8. Mo, W.Y.; Lun, C.H.I.; Choi, W.M.; Man, Y.B.; Wong, M.H. Enhancing growth and non-specific immunity of grass carp and Nile tilapia by incorporating Chinese herbs (Astragalus membranaceus and Lycium barbarum) into food waste based pellets. Environ. Pollut. 2016, 219, 475–482. [Google Scholar] [CrossRef] [PubMed]
  9. Song, X.; Feng, Z.; Zhang, Y.; Zhu, W. Regulation of dietary astragalus polysaccharide (APS) supplementation on the non-specific immune response and intestinal microbiota of sea cucumber Apostichopus japonicus. Fish Shellfish Immunol. 2019, 94, 517–524. [Google Scholar] [CrossRef]
  10. Shi, Y.; Ma, P. Pharmacological effects of Astragalus polysaccharides in treating neurodegenerative diseases. Front. Pharmcol. 2024, 15, 1449101. [Google Scholar] [CrossRef]
  11. Li, S.P.; Zhao, X.J.; Wang, J.Y. Synergy of Astragalus polysaccharides and probiotics (Lactobacillus and Bacillus cereus) on immunity and intestinal microbiota in chicks. Poult. Sci. 2009, 88, 519–525. [Google Scholar] [CrossRef] [PubMed]
  12. Wang, W.; Zhang, K.; Dai, L.; Hou, A.; Meng, P.; Ma, J. Investigating the protective effects of Astragalus polysaccharides on cyclophosphamide-induced bone marrow suppression in mice and bone mesenchymal stem cells. Mol. Immunol. 2024, 171, 93–104. [Google Scholar] [CrossRef] [PubMed]
  13. Yu, J.; Ji, H.; Dong, X.; Feng, Y.; Liu, A. Apoptosis of human gastric carcinoma MGC-803 cells induced by a novel Astragalus membranaceus polysaccharide via intrinsic mitochondrial pathways. Int. J. Biol. Macromol. 2019, 126, 811–819. [Google Scholar] [CrossRef] [PubMed]
  14. Sun, Y.; Wang, X.; Zhou, H.; Mai, K.; He, G. Dietary Astragalus polysaccharides ameliorates the growth performance, antioxidant capacity and immune responses in turbot (Scophthalmus maximus L.). Fish Shellfish Immunol. 2020, 99, 603–608. [Google Scholar] [CrossRef] [PubMed]
  15. Lin, S.M.; Jiang, Y.; Chen, Y.J.; Luo, L.; Doolgindachbaporn, S.; Yuangsoi, B. Effects of Astragalus polysaccharides (APS) and chitooligosaccharides (COS) on growth, immune response and disease resistance of juvenile largemouth bass, Micropterus salmoides. Fish Shellfish Immunol. 2017, 70, 40–47. [Google Scholar] [CrossRef]
  16. Pu, Y.; Wu, S. The growth performance, body composition and nonspecific immunity of white shrimps (Litopenaeus vannamei) affected by dietary Astragalus membranaceus polysaccharide. Int. J. Biol. Macromol. 2022, 209, 162–165. [Google Scholar] [CrossRef] [PubMed]
  17. Li, Y.; Dong, X.; Zhang, Y.; Xiao, T.; Zhao, Y.; Wang, H. Astragalus polysaccharide improves the growth, meat quality, antioxidant capacity and bacterial resistance of Furong crucian carp (Furong carp♀ x red crucian carp♂). Int. J. Biol. Macromol. 2023, 244, 124999. [Google Scholar] [CrossRef]
  18. Wu, S. Dietary Astragalus membranaceus polysaccharide ameliorates the growth performance and innate immunity of juvenile crucian carp (Carassius auratus). Int. J. Biol. Macromol. 2020, 149, 877–881. [Google Scholar] [CrossRef]
  19. Shi, X.; Wu, C.; Ma, H.; Liu, J.; Fu, C.; Zhou, R.; Jiang, Y.; Zhang, R. Exploring the effects of astragalus polysaccharide food supplementation on growth performance, immunity, antioxidant capacity, and intestinal microflora in Chinese mitten crabs. Aquac. Rep. 2024, 34, 101908. [Google Scholar] [CrossRef]
  20. Wei, G.; Cai, S.; Wu, Y.; Ma, S.; Huang, Y. Immune effect of Vibrio harveyi formalin-killed cells vaccine combined with chitosan oligosaccharide and astragalus polysaccharides in ♀Epinephelus fuscoguttatus x ♂symbol Epinephelus lanceolatus. Fish Shellfish Immunol. 2020, 98, 186–192. [Google Scholar] [CrossRef]
  21. Zahran, E.; Risha, E.; Abdelhamid, F.; Mahgoub, H.A.; Ibrahim, T. Effects of dietary Astragalus polysaccharides (APS) on growth performance, immunological parameters, digestive enzymes, and intestinal morphology of Nile tilapia (Oreochromis niloticus). Fish Shellfish Immunol. 2014, 38, 149–157. [Google Scholar] [CrossRef] [PubMed]
  22. Shi, X.; Jia, Y.; Zhang, Z.; Wu, W.; Wu, Z.; Chi, M.; Zhao, Q.; Li, E. The effects of Chinese herbal feed additives on physiological health and detoxification ability in the red claw crayfish, Cherax quadricarinatus, and evaluation of their safety. Aquaculture 2023, 569, 739394. [Google Scholar] [CrossRef]
  23. Zhu, X.M.; Liu, X.Y.; Xia, C.G.; Li, M.Y.; Niu, X.T.; Wang, G.Q.; Zhang, D.M. Effects of dietary Astragalus Propinquus Schischkin polysaccharides on growth performance, immunological parameters, antioxidants responses and inflammation-related gene expression in Channa argus. Comp. Biochem. Physiol. C Toxicol. Pharmacol. 2021, 249, 109121. [Google Scholar] [CrossRef] [PubMed]
  24. Shi, F.; Lu, Z.; Yang, M.; Li, F.; Zhan, F.; Zhao, L.; Li, Y.; Li, Q.; Li, J.; Li, J.; et al. Astragalus polysaccharides mediate the immune response and intestinal microbiota in grass carp (Ctenopharyngodon idellus). Aquaculture 2021, 534, 736205. [Google Scholar] [CrossRef]
  25. Qiao, Y.; Liu, C.; Guo, Y.; Zhang, W.; Guo, W.; Oleksandr, K.; Wang, Z. Polysaccharides derived from Astragalus membranaceus and Glycyrrhiza uralensis improve growth performance of broilers by enhancing intestinal health and modulating gut microbiota. Poult. Sci. 2022, 101, 101905. [Google Scholar] [CrossRef]
  26. Yu, W.; Yang, Y.; Zhou, Q.; Huang, X.; Huang, Z.; Li, T.; Wu, Q.; Zhou, C.; Ma, Z.; Lin, H. Effects of dietary Astragalus polysaccharides on growth, health and resistance to Vibrio harveyi of Lates calcarifer. Int. J. Biol. Macromol. 2022, 207, 850–858. [Google Scholar] [CrossRef]
  27. Yu, W.; Lin, H.; Yang, Y.; Zhou, Q.; Chen, H.; Huang, X.; Zhou, C.; Huang, Z.; Li, T. Effects of supplemental dietary Haematococcus pluvialison growth performance, antioxidant capacity, immune responses and resistance to Vibrio harveyi challenge of spotted sea bass Lateolabrax maculatus. Aquac. Nutr. 2020, 27, 355–365. [Google Scholar] [CrossRef]
  28. AOAC. Official Methods for Analysis, 19th ed.; Association of Official Analytical Chemists: Washington, DC, USA, 2012. [Google Scholar]
  29. Livak, K.J.; Schmittgen, T.D. Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method. Methods 2001, 25, 402–408. [Google Scholar] [CrossRef]
  30. Xie, J.; Niu, J. Evaluation of four macro-algae on growth performance, anti-oxidant capacity and non-specific immunity in golden pompano (Trachinotus ovatus). Aquaculture 2022, 548, 737690. [Google Scholar] [CrossRef]
  31. Zhang, H.; Ding, Q.; Wang, A.; Liu, Y.; Teame, T.; Ran, C.; Yang, Y.; He, S.; Zhou, W.; Olsen, R.E.; et al. Effects of dietary sodium acetate on food intake, weight gain, intestinal digestive enzyme activities, energy metabolism and gut microbiota in cultured fish: Zebrafish as a model. Aquaculture 2020, 523, 735188. [Google Scholar] [CrossRef]
  32. Duan, Y.; Zhao, H.; Qin, C.; Ma, L.; Bi, X.; Song, T.; Sun, X.; Sun, J. Astragalus polysaccharides, cinnamaldehyde and their complexes affected growth, physicochemical parameters, histomorphology and flesh quality of Largemouth bass (Micropterus salmoides). Aquac. Rep. 2024, 35, 101989. [Google Scholar] [CrossRef]
  33. Sun, S.; Bian, C.; Zhou, N.; Shen, Z.; Yu, M. Dietary Astragalus polysaccharides improve the growth and innate immune response of giant freshwater prawn Macrobrachium rosenbergii: Insights from the brain-gut axis. Int. J. Biol. Macromol. 2023, 243, 125158. [Google Scholar] [CrossRef]
  34. Huang, Z.; Ye, Y.; Xu, A.; Li, Z. Effects of Astragalus membranaceus Polysaccharides on Growth Performance, Physiological and Biochemical Parameters, and Expression of Genes Related to Lipid Metabolism of Spotted Sea Bass, Lateolabrax maculatus. Aquac. Nutr. 2023, 2023, 6191330. [Google Scholar] [CrossRef] [PubMed]
  35. Yu, L.; Wen, H.; Jiang, M.; Wu, F.; Tian, J.; Lu, X.; Xiao, J.; Liu, W. Effects of ferulic acid on intestinal enzyme activities, morphology, microbiome composition of genetically improved farmed tilapia (Oreochromis niloticus) fed oxidized fish oil. Aquaculture 2020, 528, 735543. [Google Scholar] [CrossRef]
  36. Li, Y.; Ran, C.; Wei, K.; Xie, Y.; Xie, M.; Zhou, W.; Yang, Y.; Zhang, Z.; Lv, H.; Ma, X.; et al. The effect of Astragalus polysaccharide on growth, gut and liver health, and anti-viral immunity of zebrafish. Aquaculture 2021, 540, 736677. [Google Scholar] [CrossRef]
  37. Qiu, J.; Wang, W.N.; Wang, L.J.; Liu, Y.F.; Wang, A.L. Oxidative stress, DNA damage and osmolality in the Pacific white shrimp, Litopenaeus vannamei exposed to acute low temperature stress. Comp. Biochem. Physiol. C Toxicol. Pharmacol. 2011, 154, 36–41. [Google Scholar] [CrossRef]
  38. Li, L.; Wei, X.F.; Yang, Z.Y.; Zhu, R.; Li, D.L.; Shang, G.J.; Wang, H.T.; Meng, S.T.; Wang, Y.T.; Liu, S.Y.; et al. Alleviative effect of poly-β-hydroxybutyrate on lipopolysaccharide-induced oxidative stress, inflammation and cell apoptosis in Cyprinus carpio. Int. J. Biol. Macromol. 2023, 253, 126784. [Google Scholar] [CrossRef] [PubMed]
  39. Zhang, W.; Zhang, M.; Cheng, A.; Hao, E.; Huang, X.; Chen, X. Immunomodulatory and antioxidant effects of Astragalus polysaccharide liposome in large yellow croaker (Larimichthys crocea). Fish Shellfish Immunol. 2020, 100, 126–136. [Google Scholar] [CrossRef]
  40. Yu, W.; Yang, Y.; Chen, H.; Zhou, Q.; Zhang, Y.; Huang, X.; Huang, Z.; Li, T.; Zhou, C.; Ma, Z.; et al. Effects of dietary chitosan on the growth, health status and disease resistance of golden pompano (Trachinotus ovatus). Carbohydr. Polym. 2023, 300, 120237. [Google Scholar] [CrossRef]
  41. Zhu, X.; Hao, R.; Zhang, J.; Tian, C.; Hong, Y.; Zhu, C.; Li, G. Improved growth performance, digestive ability, antioxidant capacity, immunity and Vibrio harveyi resistance in coral trout (Plectropomus leopardus) with dietary vitamin C. Aquac. Rep. 2022, 24, 101111. [Google Scholar] [CrossRef]
  42. Luo, L.; Meng, X.; Wang, S.; Zhang, R.; Guo, K.; Zhao, Z. Effects of dietary ginger (Zingiber officinale) polysaccharide on the growth, antioxidant, immunity response, intestinal microbiota, and disease resistance to Aeromonas hydrophila in crucian carp (Carassius auratus). Int. J. Biol. Macromol. 2024, 275, 133711. [Google Scholar] [CrossRef]
  43. Citarasu, T. Herbal biomedicines: A new opportunity for aquaculture industry. Aquac. Int. 2009, 18, 403–414. [Google Scholar] [CrossRef]
  44. Lin, Z.; Pan, L.; Xie, R.; Li, L.; Wen, J.; Zhou, X.; Dong, X.; Xie, S.; Tan, B.; Liu, H. Effects of dietary artemisinin on growth performance, digestive enzyme activity, intestinal microbiota, antioxidant capacity and immune biomarkers of Coral trout (Plectropomus leopardus). Aquac. Rep. 2023, 29, 101525. [Google Scholar] [CrossRef]
  45. Paimeeka, S.; Tangsongcharoen, C.; Lertwanakarn, T.; Setthawong, P.; Bunkhean, A.; Tangwattanachuleeporn, M.; Surachetpong, W. Tilapia lake virus infection disrupts the gut microbiota of red hybrid tilapia (Oreochromis spp.). Aquaculture 2024, 586, 740752. [Google Scholar] [CrossRef]
  46. Mekuchi, M.; Asakura, T.; Sakata, K.; Yamaguchi, T.; Teruya, K.; Kikuchi, J. Intestinal microbiota composition is altered according to nutritional biorhythms in the leopard coral grouper (Plectropomus leopardus). PLoS ONE 2018, 13, e0197256. [Google Scholar] [CrossRef] [PubMed]
  47. Lin, S.M.; Zhou, X.M.; Zhou, Y.L.; Kuang, W.M.; Chen, Y.J.; Luo, L.; Dai, F.Y. Intestinal morphology, immunity and microbiota response to dietary fibers in largemouth bass, Micropterus salmoide. Fish Shellfish Immunol. 2020, 103, 135–142. [Google Scholar] [CrossRef]
  48. Shi, H.-T.; Zhao, S.-Z.; Wang, K.-L.; Fan, M.-X.; Han, Y.-Q.; Wang, H.-L. Effects of dietary Astragalus Membranaceus supplementation on growth performance, and intestinal morphology, microbiota and metabolism in common carp (Cyprinus carpio). Aquac. Rep. 2022, 22, 100955. [Google Scholar] [CrossRef]
  49. Smriga, S.; Sandin, S.A.; Azam, F. Abundance, diversity, and activity of microbial assemblages associated with coral reef fish guts and feces. FEMS Microbiol. Ecol. 2010, 73, 31–42. [Google Scholar] [CrossRef]
  50. Macias, L.; Mercado, V.; Olmos, J. Assessment of Bacillus species capacity to protect Nile tilapia from A. hydrophila infection and improve growth performance. Front. Cell. Infect. Microbiol. 2024, 14, 1354736. [Google Scholar] [CrossRef]
  51. Li, Z.; Du, Q.; Jiao, T.; Zhu, Z.; Wan, X.; Ju, C.; Liu, H.; Li, Q. Effects of probiotic supplementary bioflocs (Rhodospirillum rubrum, Bacillus subtilis, Providencia rettgeri) on growth, immunity, and water quality in cultures of Pacific white shrimp (Litopenaeus vannamei). Aquaculture 2024, 591, 741141. [Google Scholar] [CrossRef]
  52. Lin, H.; Tan, B.; Yang, Q. The Effect of Glycerol Monolaurate on Intestinal Health and Disease Resistance in Cage-Farmed Juvenile Pompano Trachinotus ovatus. Aquac. Nutr. 2023, 2023, 8580240. [Google Scholar] [CrossRef]
Microorganisms 12 01980 g001
Figure 1. Prediction of the Astragalus polysaccharides (APS) dose required for maximal SGR of coral trout (Plectropomus leopardus) using cubic regression analysis. Values are shown as the mean ± SE (n = 3). Different letters indicate significant differences between the treatments.
Figure 1. Prediction of the Astragalus polysaccharides (APS) dose required for maximal SGR of coral trout (Plectropomus leopardus) using cubic regression analysis. Values are shown as the mean ± SE (n = 3). Different letters indicate significant differences between the treatments.
Microorganisms 12 01980 g001
Microorganisms 12 01980 g002
Figure 2. Intestinal morphology in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels (long arrow, villus length; short arrow, muscle thickness). (A) 0% APS; (B) 0.05% APS; (C) 0.10% APS; (D) 0.15% APS; (E) 0.20% APS; (F) villus length; (G) muscle thickness. Scale bar, 200 μm. Values are shown as the mean ± SE (n = 3). Different letters indicate a significant difference.
Figure 2. Intestinal morphology in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels (long arrow, villus length; short arrow, muscle thickness). (A) 0% APS; (B) 0.05% APS; (C) 0.10% APS; (D) 0.15% APS; (E) 0.20% APS; (F) villus length; (G) muscle thickness. Scale bar, 200 μm. Values are shown as the mean ± SE (n = 3). Different letters indicate a significant difference.
Microorganisms 12 01980 g002
Microorganisms 12 01980 g003
Figure 3. Expression of liver antioxidant enzyme (A) and immune indicator (B) genes in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels. Values are shown as the mean ± SE (n = 3). The full names of the PCR target genes (SOD-1, SOD-2, CAT, GSH-Px1a, ACP6, AKP, C3, C4-b, IgM, LZ-c, and GAPDH) are provided in Table S2. Different letters indicate a significant difference.
Figure 3. Expression of liver antioxidant enzyme (A) and immune indicator (B) genes in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels. Values are shown as the mean ± SE (n = 3). The full names of the PCR target genes (SOD-1, SOD-2, CAT, GSH-Px1a, ACP6, AKP, C3, C4-b, IgM, LZ-c, and GAPDH) are provided in Table S2. Different letters indicate a significant difference.
Microorganisms 12 01980 g003
Microorganisms 12 01980 g004
Figure 4. Alpha-diversity and beta-diversity of the gut bacterial community in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels. (A) Chao1, Shannon, and Simpson index. Values are shown as the mean ± SE (n = 3) via the student’s two-tailed t-test. Different symbols (*, p < 0.05; ns, not significant) indicate significant differences (p < 0.05). (B) Rarefaction curve of the intestines in coral trout fed different APS dietary levels. (C) PCoA (Principal Co-ordinates Analysis) of the intestines in coral trout fed different APS dietary levels based on weighted UniFrac distances. Control, 0% APS group; APS, 0.15% APS group.
Figure 4. Alpha-diversity and beta-diversity of the gut bacterial community in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels. (A) Chao1, Shannon, and Simpson index. Values are shown as the mean ± SE (n = 3) via the student’s two-tailed t-test. Different symbols (*, p < 0.05; ns, not significant) indicate significant differences (p < 0.05). (B) Rarefaction curve of the intestines in coral trout fed different APS dietary levels. (C) PCoA (Principal Co-ordinates Analysis) of the intestines in coral trout fed different APS dietary levels based on weighted UniFrac distances. Control, 0% APS group; APS, 0.15% APS group.
Microorganisms 12 01980 g004
Microorganisms 12 01980 g005
Figure 5. Bacterial compositions in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels. (A,B) Distribution of the top 10 microbial phylum levels in different groups, with the legend shown on the right. (C,D) Distribution of the top 10 microbial genus levels in different groups, with the legend shown on the right. Control, 0% APS group; APS, 0.15% APS group.
Figure 5. Bacterial compositions in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels. (A,B) Distribution of the top 10 microbial phylum levels in different groups, with the legend shown on the right. (C,D) Distribution of the top 10 microbial genus levels in different groups, with the legend shown on the right. Control, 0% APS group; APS, 0.15% APS group.
Microorganisms 12 01980 g005
Table 1. Growth performance in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels.
Table 1. Growth performance in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels.
ParametersDiets (APS %)
00.050.100.150.20
IBW (g)18.61 ± 0.1118.49 ± 0.1718.71 ± 0.0718.50 ± 0.0718.79 ± 0.13
FBW (g)30.82 ±0.41 a32.34 ±0.86 ab34.12 ± 0.70 bc35.67 ± 0.73 c33.38 ± 0.57 b
WGR (%)65.60 ± 1.50 a74.95 ± 6.04 ab82.34 ± 4.41 bc92.86 ± 4.52 c77.67 ± 3.85 ab
SGR (%)0.90 ± 0.02 a1.00 ± 0.06 ab1.07 ± 0.04 bc1.17 ± 0.04 c1.03 ± 0.04 ab
SR (%)96.67 ± 1.6795.00 ± 2.89100.00 ± 0.00100.00 ± 0.0096.67 ± 1.67
VSI (%)4.87 ± 0.134.99 ± 0.115.17 ± 0.105.21 ± 0.125.19 ± 0.18
HSI (%)1.04 ± 0.041.05 ± 0.091.08 ± 0.061.09 ± 0.041.06 ± 0.04
CF (%)2.17 ± 0.042.19 ± 0.062.22 ± 0.032.24 ± 0.062.12 ± 0.03
Values are shown as the mean ± SE (n = 3). IBW, initial body weight; FBW, final body weight; WGR, weight gain rate; SGR, specific growth rate; SR, survival rate; VSI, visceral somatic index; HSI, hepatic somatic indices; CF, condition factor. Different letters indicate significant differences between the treatments.
Table 2. Digestive enzyme activities in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels.
Table 2. Digestive enzyme activities in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels.
ParametersDiets (APS %)
00.050.100.150.20
α-Amylase (U/mg prot)0.62 ± 0.05 a0.70 ± 0.04 ab0.78 ± 0.04 b0.85 ± 0.06 b0.75 ± 0.04 ab
Lipase (U/g prot)1.34 ± 0.05 a1.47 ± 0.06 ab1.57 ± 0.09 b1.66 ± 0.07 b1.54 ± 0.04 ab
Chymotrypsin (U/mg prot)0.92 ± 0.060.98 ± 0.071.13 ± 0.051.16 ± 0.111.12 ± 0.09
Values are shown as the mean ± SE (n = 3). Different letters indicate significant differences between the treatments.
Table 3. Liver antioxidant ability in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels.
Table 3. Liver antioxidant ability in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels.
ParametersDiets (APS %)
00.050.100.150.20
SOD activity (U/mg prot)41.66 ± 7.72 a56.84 ± 2.51 ab64.62 ± 6.81 b68.79 ± 3.17 b60.22 ± 8.51 ab
CAT activity (U/mg prot)7.73 ± 0.45 a8.12 ± 0.23 ab8.44 ± 0.57 ab9.26 ± 0.49 b8.07 ± 0.39 ab
GSH-Px activity (U/mg prot)26.80 ± 1.30 a29.63 ± 1.74 ab31.98 ± 1.18 b36.63 ± 1.47 c28.88 ± 1.03 ab
T-AOC levels (U/mg prot)0.74 ± 0.02 a0.78 ± 0.03 ab0.85 ± 0.02 bc0.91 ± 0.02 c0.80 ± 0.03 ab
MDA content (nmol/mg prot)6.44 ± 0.18 b5.89 ± 0.17 b4.94 ± 0.21 a4.69 ± 0.22 a4.84 ± 0.20 a
Values are shown as the mean ± SE (n = 3). SOD, superoxide dismutase; CAT, catalase; GSH-Px, glutathione peroxidase; T-AOC, total antioxidant capacity; MDA, malondialdehyde. Different letters indicate significant differences between the treatments.
Table 4. Liver immune ability in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels.
Table 4. Liver immune ability in coral trout (Plectropomus leopardus) fed different Astragalus polysaccharides (APS) dietary levels.
ParametersDiets (APS %)
00.050.100.150.20
ACP activity (U/g prot)441.91 ± 6.67 a509.27 ± 10.40 b535.59 ± 20.48 bc563.56 ± 17.67 c528.06 ± 9.25 bc
AKP activity (U/g prot)87.01 ± 2.96 a98.50 ± 4.57 ab99.70 ± 5.84 ab105.81 ± 6.99 b98.03 ± 3.15 ab
C3 content (μg/mg prot)142.54 ± 9.26 a150.56 ± 6.42 a188.37 ± 6.75 b191.58 ± 9.57 b157.58 ± 9.06 a
C4 content (μg/mg prot)27.21 ± 3.96 a34.16 ± 1.24 ab36.35 ± 2.80 ab39.18 ± 2.76 b27.70 ± 3.39 a
IgM content (μg/mg prot)49.03 ± 1.12 ab45.02 ± 1.67 a55.73 ± 3.42 bc60.40 ± 2.33 c45.43 ± 3.34 a
LZ activity (μg/mg prot)143.92 ± 5.47 a148.98 ± 3.70 ab164.79 ± 2.43 c165.55 ± 4.69 c161.48 ± 2.86 bc
Values are shown as the mean ± SE (n = 3). ACP, acid phosphatase; AKP, alkaline phosphatase; C3, complement 3; C4, complement 4; IgM, immunoglobulin M; LZ, lysozyme. Different letters indicate significant differences between the treatments.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Hao, X.; Lin, H.; Lin, Z.; Yang, K.; Hu, J.; Ma, Z.; Yu, W. Effect of Dietary Astragalus polysaccharides (APS) on the Growth Performance, Antioxidant Responses, Immunological Parameters, and Intestinal Microbiota of Coral Trout (Plectropomus leopardus). Microorganisms 2024, 12, 1980. https://doi.org/10.3390/microorganisms12101980

AMA Style

Hao X, Lin H, Lin Z, Yang K, Hu J, Ma Z, Yu W. Effect of Dietary Astragalus polysaccharides (APS) on the Growth Performance, Antioxidant Responses, Immunological Parameters, and Intestinal Microbiota of Coral Trout (Plectropomus leopardus). Microorganisms. 2024; 12(10):1980. https://doi.org/10.3390/microorganisms12101980

Chicago/Turabian Style

Hao, Xiaoqi, Heizhao Lin, Ziyang Lin, Keng Yang, Jing Hu, Zhenhua Ma, and Wei Yu. 2024. "Effect of Dietary Astragalus polysaccharides (APS) on the Growth Performance, Antioxidant Responses, Immunological Parameters, and Intestinal Microbiota of Coral Trout (Plectropomus leopardus)" Microorganisms 12, no. 10: 1980. https://doi.org/10.3390/microorganisms12101980

APA Style

Hao, X., Lin, H., Lin, Z., Yang, K., Hu, J., Ma, Z., & Yu, W. (2024). Effect of Dietary Astragalus polysaccharides (APS) on the Growth Performance, Antioxidant Responses, Immunological Parameters, and Intestinal Microbiota of Coral Trout (Plectropomus leopardus). Microorganisms, 12(10), 1980. https://doi.org/10.3390/microorganisms12101980

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop