International Journal of Environmental Research and Public Health

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16 pages, 1690 KiB

Open AccessArticle

The Prevention of Bio-Organic Fertilizer Fermented from Cow Manure Compost by Bacillus sp. XG-1 on Watermelon Continuous Cropping Barrier

by Hao Zhang, Zi-Wei Hua, Wen-Zhi Liang, Qiu-Hong Niu and Xiang Wang

Int. J. Environ. Res. Public Health 2020, 17(16), 5714; https://doi.org/10.3390/ijerph17165714 - 7 Aug 2020

Cited by 8 | Viewed by 4670

Abstract

The continuous cropping barrier is an important factor leading to the decline of watermelon quality and yield. In this study, we focused on a bio-organic fertilizer prepared with one bacterial strain, Bacillus sp. XG-1, to prevent the occurrence of the continuous cropping barrier. [...] Read more.

The continuous cropping barrier is an important factor leading to the decline of watermelon quality and yield. In this study, we focused on a bio-organic fertilizer prepared with one bacterial strain, Bacillus sp. XG-1, to prevent the occurrence of the continuous cropping barrier. The strain XG-1 was isolated from watermelon rhizosphere soil, and promoted the growth of watermelon by producing phytase (0.19 U/mL), indole-3-acetic acid (IAA, 7.31 mg/L), and gibberellins (GA3, 2.47 mg/L). In addition, the strain also possessed a strong antagonistic effect against the pathogen Fusarium oxysporum f. sp. niveum (Fon) by inhibiting conidia germination with an inhibition ratio of 85.3% and mycelium growth. The bio-organic fertilizer fermented by XG-1, based on cow manure compost and rapeseed meal (85:15, w/w) under optimal conditions, was mixed in soil (watermelon had been planted for two consecutive years). After the cultivation of watermelon for 50 d, a higher density of XG-1 (9.79 × 10⁵ colony-forming units (CFU)/g) and one order of magnitude lower of Fon (1.29 × 10³ copies/g) were detected in the rhizosphere soil compared with soils without bio-organic fertilizer (7.59 × 10⁴ copies/g for Fon), leading to an 86.4% control efficiency of watermelon caused by Fusarium wilt. The application of bio-organic fertilizer enriched soil nutrients, including the organic matter (13.2%), total nitrogen (13.9%), total phosphorus (20.5%), and total potassium (3.77%), adjusted the soil pH from 6.69 to 7.01, and significantly improved the watermelon growth in terms of the seedling height, root length, fresh weight of seedling and root with increase of 78.8%, 72.2%, 84.6%, and 96.4%, respectively. This study regarded the watermelon continuous cropping soil as the research point, and focused on inhibiting Fon, regulating soil properties and enhancing watermelon growth to eliminate the continuous cropping barrier through a combination of compost and functional strains, demonstrating the potential application value in watermelon production. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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15 pages, 2652 KiB

Open AccessArticle

A Simplified Protocol for Reversing Phenotypic Conversion of Ralstonia solanacearum during Experimentation

by Pramod Kumar Sahu, Shailendra Singh, Amrita Gupta, Udai B. Singh, Surinder Paul, Diby Paul, Pandiyan Kuppusamy, Harsh V. Singh and Anil Kumar Saxena

Int. J. Environ. Res. Public Health 2020, 17(12), 4274; https://doi.org/10.3390/ijerph17124274 - 15 Jun 2020

Cited by 6 | Viewed by 3160

Abstract

Background: Ralstonia solanacearum has the problem of losing the virulence in laboratory conditions, during prolonged experimentation. Since pure colonies of R. solanacearum contain cell fractions differing in virulence, it was considered worthwhile to find a way of selecting the cells with lower attenuation. [...] Read more.

Background: Ralstonia solanacearum has the problem of losing the virulence in laboratory conditions, during prolonged experimentation. Since pure colonies of R. solanacearum contain cell fractions differing in virulence, it was considered worthwhile to find a way of selecting the cells with lower attenuation. Therefore, a methodology for inducing virulent-type colonies occurrence in Ralstonia solanacearum was developed. Methods: Nutrient gradient was created by swabbing R. solanacearum culture in a slanted KMTTC medium, and Phyllanthus emblica extract was given by well diffusion. Live–dead cell imaging using BacLight, effects of ascorbic acid on cell viability, and production of virulence factors (exopolysaccharides, cellulase, and pectinase) supported this hypothesis. The tagging of R. solanacearum with green fluorescent protein and further confocal scanning laser microscopic visualization confirmed the colonization in vascular bundles of tomato. Results: P. emblica extract suppressed R. solanacearum initially in well diffusion, but further developed virulent-type colonies around the wells. Nutrient deprivation was found to have synergistic effects with P. emblica extract. The converted fluidal (virulent type) colonies could be able to colonize vascular bundles and cause wilting symptoms. Conclusion: This method will be useful in the laboratories working on biocontrol of R. solanacearum for maintaining virulent-type colonies. Moreover, it could form the basis for studies on the stability of phenotypic conversion and cell fractions in R. solanacearum. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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30 pages, 4374 KiB

Open AccessArticle

Seed Biopriming with Microbial Inoculant Triggers Local and Systemic Defense Responses against Rhizoctonia solani Causing Banded Leaf and Sheath Blight in Maize (Zea mays L.)

by Shailendra Singh, Udai B. Singh, Deepti Malviya, Surinder Paul, Pramod Kumar Sahu, Mala Trivedi, Diby Paul and Anil Kumar Saxena

Int. J. Environ. Res. Public Health 2020, 17(4), 1396; https://doi.org/10.3390/ijerph17041396 - 21 Feb 2020

Cited by 48 | Viewed by 4982

Abstract

Plant growth promoting rhizobacteria Pseudomonas aeruginosa strain MF-30 isolated from maize rhizosphere was characterized for several plant growth stimulating attributes. The strain MF-30 was also evaluated for antifungal properties against Rhizoctonia solani causing banded leaf and sheath blight in maize (Zea mays [...] Read more.

Plant growth promoting rhizobacteria Pseudomonas aeruginosa strain MF-30 isolated from maize rhizosphere was characterized for several plant growth stimulating attributes. The strain MF-30 was also evaluated for antifungal properties against Rhizoctonia solani causing banded leaf and sheath blight in maize (Zea mays L.) under in vitro conditions and was found to have higher mycelial growth suppression in the culture suspension (67.41%) followed by volatile organic compounds (62.66%) and crude extract (51.20%) in a dual plate assay. The endophytic and epiphytic colonization ability was tested using Green Fluorescent Protein (GFP)-tagging. Visualization through confocal scanning laser microscope clearly indicated that strain MF-30 colonizes the root and foliar parts of the plants. Further, the effects of seed bio-priming with P. aeruginosa MF-30 was evaluated in the induction and bioaccumulation of defense-related biomolecules, enzymes, natural antioxidants, and other changes in maize under pot trial. This not only provided protection from R. solani but also ensured growth promotion under pathogenic stress conditions in maize. The maximum concentration of hydrogen peroxide (H₂O₂) was reported in the root and shoot of the plants treated with R. solani alone (8.47 and 17.50 mmol mg⁻¹ protein, respectively) compared to bioagent, P. aeruginosa MF-30 bio-primed plants (3.49 and 7.50 mmol mg⁻¹ protein, respectively). Effects on total soluble sugar content, total protein, and total proline were also found to enhanced significantly due to inoculation of P. aeruginosa MF-30. The activities of anti-oxidative defense enzymes phenylalanine ammonia lyase (PAL), ascorbate peroxidase, peroxidase, superoxide dismutase, and catalase increased significantly in the plants bio-primed with P. aeruginosa MF-30 and subsequent foliar spray of culture suspension of MF-30 compared to pathogen alone inoculated plants. qRT-PCR analysis revealed that seed bio-priming and foliar application of P. aeruginosa MF-30 significantly increased the expression of PR-1 and PR-10 genes with the simultaneous decrease in the disease severity and lesion length in the maize plants under pathogenic stress conditions. A significant enhancement of shoot and root biomass was recorded in MF-30 bio-primed plants as compared to untreated control (p < 0.05). Significant increase in plant growth and antioxidant content, as well as decreased disease severity in the P. aeruginosa MF-30 bio-primed plants, suggested the possibility of an eco-friendly and economical means of achieving antioxidants-rich, healthier maize plants. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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18 pages, 4827 KiB

Open AccessArticle

Rhizosphere Bacterial Community Structure and Predicted Functional Analysis in the Water-Level Fluctuation Zone of the Danjiangkou Reservoir in China During the Dry Period

by Zhao-Jin Chen, Yang Shao, Ying-Jun Li, Li-An Lin, Yan Chen, Wei Tian, Bai-Lian Li and Yu-Ying Li

Int. J. Environ. Res. Public Health 2020, 17(4), 1266; https://doi.org/10.3390/ijerph17041266 - 16 Feb 2020

Cited by 11 | Viewed by 3991

Abstract

The water-level fluctuation zone (WLFZ) is a transitional zone between terrestrial and aquatic ecosystems. Plant communities that are constructed artificially in the WLFZ can absorb and retain nutrients such as nitrogen (N) and phosphorus (P). However, the microbial community composition and function associated [...] Read more.

The water-level fluctuation zone (WLFZ) is a transitional zone between terrestrial and aquatic ecosystems. Plant communities that are constructed artificially in the WLFZ can absorb and retain nutrients such as nitrogen (N) and phosphorus (P). However, the microbial community composition and function associated with this process have not been elucidated. In this study, four artificially constructed plant communities, including those of herbs (Cynodon dactylon and Chrysopogon zizanioides), trees (Metasequoia glyptostroboides), and shrubs (Salix matsudana) from the newly formed WLFZ of the Danjiangkou Reservoir were evaluated. The bacterial community compositions were analyzed by 16S rRNA gene sequencing using a MiSeq platform, and the functions of these communities were assessed via Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis. The results showed that the bacterial communities primarily comprised 362 genera from 24 phyla, such as Proteobacteria, Acidobacteria, Actinobacteria, and Gemmatimonadetes, showing the richness of the community composition. Planting altered the bacterial community composition, with varying effects observed among the different plant types. The bacterial community functional analysis revealed that these bacteria were primarily associated with six biological metabolic pathway categories (e.g., metabolism, genetic information processing, and environmental information processing) with 34 subfunctions, showing the richness of community functions. The planting of M. glyptostroboides, S. matsudana, and C. dactylon improved the metabolic capabilities of bacterial communities. N- and P-cycling gene analysis showed that planting altered the N- and P-cycling metabolic capacities of soil bacteria. The overall N- and P-metabolic capacity was highly similar between C. dactylon and C. zizanioides samples and between S. matsudana and M. glyptostroboides samples. The results of this study provide a preliminary analysis of soil bacterial community structure and function in the WLFZ of the Danjiangkou Reservoir and provides a reference for vegetation construction in this zone. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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19 pages, 7789 KiB

Open AccessArticle

Flooding Irrigation Weakens the Molecular Ecological Network Complexity of Soil Microbes during the Process of Dryland-to-Paddy Conversion

by Xiaoxiao Li, Qi Zhang, Jing Ma, Yongjun Yang, Yifei Wang and Chen Fu

Int. J. Environ. Res. Public Health 2020, 17(2), 561; https://doi.org/10.3390/ijerph17020561 - 15 Jan 2020

Cited by 20 | Viewed by 3638

Abstract

Irrigation has been applied on a large scale for the improvement of grain yield per hectare and production stability. However, the dryland-to-paddy conversion affects the ecological environment of areas of long-term dry farming, especially soil microorganisms. Little attention has been paid to the [...] Read more.

Irrigation has been applied on a large scale for the improvement of grain yield per hectare and production stability. However, the dryland-to-paddy conversion affects the ecological environment of areas of long-term dry farming, especially soil microorganisms. Little attention has been paid to the changes in microbial communities and the interactions between their populations in this process. Therefore, in this paper, the compositions and diversity of soil bacterial and fungal communities were explored through a combination of high-throughput sequencing technology and molecular ecological network methods using bacterial 16S rRNA and fungal ITS. The results showed that: (1) both the abundance and diversity of soil bacteria and fungi decreased in a short time, and the abundance of Actinobacteria, Firmicutes and Olpidiomycota varied greatly. (2) Compared to dry land, the modular structure of interaction networks and interspecific relationships of bacterial and fungal communities in paddy soil were simpler, and the network became more unstable. A cooperative relationship dominated in the molecular ecological network of bacteria, while a competitive relationship was dominant in the network of fungi. Actinobacteria and Firmicutes were the dominant bacterial species in dry land and paddy field, respectively. Ascomycota was dominant in the fungal communities of both dry land and paddy field. (3) The change in soil environmental factors, such as pH, electrical conductivity (EC), organic matter (OM) and available potassium (AK), directly affected the soil microbial community structure, showing a significant correlation (p < 0.05). These environmental factors also influenced the dominant microbial species. Microorganisms are the most important link in the carbon and nitrogen cycles of soil, and a large-scale dryland-to-paddy conversion may reduce the ecological stability of regional soil. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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19 pages, 4543 KiB

Open AccessArticle

Seed Biopriming with Salt-Tolerant Endophytic Pseudomonas geniculata-Modulated Biochemical Responses Provide Ecological Fitness in Maize (Zea mays L.) Grown in Saline Sodic Soil

by Shailendra Singh, Udai B. Singh, Mala Trivedi, Pramod Kumar Sahu, Surinder Paul, Diby Paul and Anil Kumar Saxena

Int. J. Environ. Res. Public Health 2020, 17(1), 253; https://doi.org/10.3390/ijerph17010253 - 30 Dec 2019

Cited by 43 | Viewed by 4768

Abstract

Under changing climate, soil salinity and sodicity is a limiting factor to crop production and are considered a threat to sustainability in agriculture. A number of attempts are being made to develop microbe-based technologies for alleviation of toxic effects of salts. However, the [...] Read more.

Under changing climate, soil salinity and sodicity is a limiting factor to crop production and are considered a threat to sustainability in agriculture. A number of attempts are being made to develop microbe-based technologies for alleviation of toxic effects of salts. However, the mechanisms of salt tolerance in agriculturally important crops are not fully understood and still require in-depth study in the backdrop of emerging concepts in biological systems. The present investigation was aimed to decipher the microbe-mediated mechanisms of salt tolerance in maize. Endophytic Pseudomonas geniculate MF-84 was isolated from maize rhizosphere and tagged with green fluorescent protein for localization in the plant system. Confocal microphotographs clearly indicate that MF-84 was localized in the epidermal cells, cortical tissues, endodermis and vascular bundles including proto-xylem, meta-xylem, phloem and bundle sheath. The role of P. geniculate MF-84 in induction and bioaccumulation of soluble sugar, proline and natural antioxidants enzymes in maize plant was investigated which lead not only to growth promotion but also provide protection from salt stress in maize. Results suggested that application of P. geniculate MF-84 reduces the uptake of Na⁺ and increases uptake of K⁺ and Ca²⁺ in maize roots indicative of the role of MF-84 in maintaining ionic balance/homeostasis in the plant roots under higher salt conditions. It not only helps in alleviation of toxic effects of salt but also increases plant growth along with reduction in crop losses due to salinity and sodicity. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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18 pages, 7719 KiB

Open AccessArticle

Cracks Reinforce the Interactions among Soil Bacterial Communities in the Coal Mining Area of Loess Plateau, China

by Zhanbin Luo, Jing Ma, Fu Chen, Xiaoxiao Li, Huping Hou and Shaoliang Zhang

Int. J. Environ. Res. Public Health 2019, 16(24), 4892; https://doi.org/10.3390/ijerph16244892 - 4 Dec 2019

Cited by 15 | Viewed by 3010

Abstract

Soil microorganisms play a key role in global biogeochemical changes. To understand the interactions among soil bacterial communities and their responses to extreme environments, the soil properties and bacterial community diversity were determined in the post-mining ecosystem of the Loess Plateau, China. The [...] Read more.

Soil microorganisms play a key role in global biogeochemical changes. To understand the interactions among soil bacterial communities and their responses to extreme environments, the soil properties and bacterial community diversity were determined in the post-mining ecosystem of the Loess Plateau, China. The results showed that the soil temperature, pH, organic matter, available phosphorus, and available potassium values were significantly reduced in the post-mining cracks area. However, the richness and uniformity of soil bacterial communities increased by about 50% in the post-mining cracks area. Soil microbial community structure and the network interactions tended to be complex and strengthened in the post-mining cracks area. Moreover, soil nutrient loss caused the differences in soil bacterial community structure compositions in the post-mining cracks area. Furthermore, the relationships between soil physicochemical properties and different modules of the soil bacterial molecular ecological network were changed in a complex manner in the post-mining cracks area. This study provides a theoretical basis for adaptive management and response to cracks in post-mining areas and under other extreme conditions. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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18 pages, 10605 KiB

Open AccessArticle

Spatial-Temporal Variation of Bacterial Communities in Sediments in Lake Chaohu, a Large, Shallow Eutrophic Lake in China

by Lei Zhang, Yu Cheng, Guang Gao and Jiahu Jiang

Int. J. Environ. Res. Public Health 2019, 16(20), 3966; https://doi.org/10.3390/ijerph16203966 - 17 Oct 2019

Cited by 25 | Viewed by 4708

Abstract

Sediment bacterial communities are critical for the circulation of nutrients in lake ecosystems. However, the bacterial community function and co-occurrence models of lakes have not been studied in depth. In this study, we observed significant seasonal changes and non-significant spatial changes in the [...] Read more.

Sediment bacterial communities are critical for the circulation of nutrients in lake ecosystems. However, the bacterial community function and co-occurrence models of lakes have not been studied in depth. In this study, we observed significant seasonal changes and non-significant spatial changes in the beta diversity and community structure of sediment bacteria in Lake Chaohu. Through linear discriminant analysis effect size (LEfSe), we observed that certain taxa (from phylum to genus) have consistent enrichment between seasons. The sudden appearance of a Firmicutes population in spring samples from the Zhaohe River, an estuary of Lake Chaohu, and the dominance of Firmicutes populations in other regions suggested that exogenous pollution and environmental induction strongly impacted the assembly of bacterial communities in the sediments. Several taxa that serve as intermediate centers in Co-occurrence network analysis (i.e., Pedosphaeraceae, Phycisphaeraceae, Anaerolineaceae, and Geobacteraceae) may play an important role in sediments. Furthermore, compared with previous studies of plants and animals, the results of our study suggest that various organisms, including microorganisms, are resistant to environmental changes and/or exogenous invasions, allowing them to maintain their community structure. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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10 pages, 1257 KiB

Open AccessArticle

Reduction of Escherichia Coli Using Metal Plates with the Influenced of Applied Low Current and Physical Barrier of Filter Layers

by Michael Versoza, Wonseok Jung, Mona Loraine Barabad, Sangwon Ko, Minjeong Kim and Duckshin Park

Int. J. Environ. Res. Public Health 2019, 16(20), 3887; https://doi.org/10.3390/ijerph16203887 - 14 Oct 2019

Cited by 6 | Viewed by 2481

Abstract

Although metal contact is known to reduce bacterial growth, the effects of physical barriers and electricity need further investigation. This study examined the bacteria-reducing properties of copper and stainless-steel metal plates with an added electrical current and up to three filter layers on [...] Read more.

Although metal contact is known to reduce bacterial growth, the effects of physical barriers and electricity need further investigation. This study examined the bacteria-reducing properties of copper and stainless-steel metal plates with an added electrical current and up to three filter layers on the growth of Escherichia coli (bacteria) and MS2 bacteriophages (virus). When used with a stainless-steel plate, electricity increased bacteria reduction by 39.5 ± 2.30% in comparison with no electricity added, whereas a three-layer physical barrier decreased its efficiency. Copper also reduced the growth of bacteria, by 58.2 ± 8.23%, and the addition of electricity reduced it further (79.5 ± 2.34%). Bacteriophages were also affected by the metal contact. Further experiments showed that MS2 was also reduced by copper, to 82.9 ± 4.5% after 24 h at 37 °C. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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15 pages, 2706 KiB

Open AccessArticle

Evaluation of Fresh Water Actinomycete Bioflocculant and Its Biotechnological Applications in Wastewaters Treatment and Removal of Heavy Metals

by Mayowa Oladele Agunbiade, Carolina Pohl, Esta Van Heerden, Oluwaseun Oyekola and Anofi Ashafa

Int. J. Environ. Res. Public Health 2019, 16(18), 3337; https://doi.org/10.3390/ijerph16183337 - 10 Sep 2019

Cited by 26 | Viewed by 3849

Abstract

This study evaluated the potential of a biopolymeric flocculant produced by Terrabacter sp. isolated from Sterkfontein Dam, South Africa. Microbial flocculants aid the aggregation of suspended solutes in solutions, thus, suggesting its alternative application to inorganic and synthetic organic flocculants, which are associated [...] Read more.

This study evaluated the potential of a biopolymeric flocculant produced by Terrabacter sp. isolated from Sterkfontein Dam, South Africa. Microbial flocculants aid the aggregation of suspended solutes in solutions, thus, suggesting its alternative application to inorganic and synthetic organic flocculants, which are associated with health-related problems. The 16S rDNA analysis revealed the bacteria to have 98% similarity to Terrabacter sp. MUSC78T and the sequence was deposited in the Genbank as Terrabacter sp. with accession number KF682157.1. A series of experimental parameters such as bioflocculant dosage, cations concentrations, pH, and application of the purified bioflocculant in wastewaters treatment were investigated. In the presence of glucose as a sole carbon source, Ca²⁺ as cation at pH 8, the optimal flocculating activity attained was 85%. Optimum bioflocculant dosage of 0.5 mg/mL was able to remove chemical oxygen demand (COD), biological oxygen demand (BOD), suspended solids (SS), nitrate, and turbidity in dairy wastewater. In addition, the tested bioflocculant exhibited higher flocculating efficiency as compared to polyaluminum chloride, polyethylenime, and alum. Inductible coupled plasma optical emission spectroscopy (ICP-OES) analyses confirmed significant removal of 77.7% Fe, 74.8% Al, 61.9% Mn, and 57.6% Zn as representatives of heavy metals from treated dairy wastewater. Fourier transform infrared spectroscopy (FTIR) indicated the presence of carboxyl, hydroxyl, and amino groups in the purified bioflocculant which could be responsible for flocculation. Findings from this study showed the prospect of the studied bioflocculant as an alternative candidate in wastewater treatment and remediating of heavy metals. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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9 pages, 1455 KiB

Open AccessArticle

Isolation, Screening, and Characterization of Antibiotic-Degrading Bacteria for Penicillin V Potassium (PVK) from Soil on a Pig Farm

by Xuanjiang Yang, Miao Li, Panpan Guo, Hualong Li, Zelin Hu, Xianwang Liu and Qiang Zhang

Int. J. Environ. Res. Public Health 2019, 16(12), 2166; https://doi.org/10.3390/ijerph16122166 - 19 Jun 2019

Cited by 25 | Viewed by 4503

Abstract

(1) Background: Antibiotics are frequently used on farm animals, making animal husbandry a relatively large source of antibiotic pollution of the environment. The present study aims to isolate and acclimatize antibiotic-degrading bacterial strains for penicillin V potassium (PVK) from the contaminated soil of [...] Read more.

(1) Background: Antibiotics are frequently used on farm animals, making animal husbandry a relatively large source of antibiotic pollution of the environment. The present study aims to isolate and acclimatize antibiotic-degrading bacterial strains for penicillin V potassium (PVK) from the contaminated soil of a pig farm. (2) Methods: Bacterial strains were isolated and acclimatized by continuous enrichment of cultures with PVK as the sole carbon source. The antibiotic susceptibility test, thiol mercury salt ultraviolet spectrophotometry (TMSUS), morphological observations, and 16S rDNA sequence analysis were used to identify and characterize the isolated strains. (3) Results: Four bacterial isolates (denoted as LM-1, LM-2, LM-3, LM-4) were obtained, and two of them (LM-1, LM-2) with the highest degradation rates were identified to belong to the same genera as Bacillus. These two isolates were found to be resistant to PVK antibiotic in an antibiotic sensitivity test. The TMSUS indicated that the strains LM-1 and LM-2 had good performance in PVK degradation (68% for LM-1, 66% for LM-2 in 48 h) when the initial PVK concentration was about 100 μg/mL. (4) Conclusions: Two bacterial strains isolated from the soil on a pig farm are effective in degrading PVK and can be potentially used for bioremediation of PVK antibiotic-contaminated soils. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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15 pages, 1427 KiB

Open AccessArticle

Nitrofurantoin—Microbial Degradation and Interactions with Environmental Bacterial Strains

by Amanda Pacholak, Wojciech Smułek, Agnieszka Zgoła-Grześkowiak and Ewa Kaczorek

Int. J. Environ. Res. Public Health 2019, 16(9), 1526; https://doi.org/10.3390/ijerph16091526 - 30 Apr 2019

Cited by 29 | Viewed by 4572

Abstract

The continuous exposure of living organisms and microorganisms to antibiotics that have increasingly been found in various environmental compartments may be perilous. One group of antibacterial agents that have an environmental impact that has been very scarcely studied is nitrofuran derivatives. Their representative [...] Read more.

The continuous exposure of living organisms and microorganisms to antibiotics that have increasingly been found in various environmental compartments may be perilous. One group of antibacterial agents that have an environmental impact that has been very scarcely studied is nitrofuran derivatives. Their representative is nitrofurantoin (NFT)—a synthetic, broad-spectrum antibiotic that is often overdosed. The main aims of the study were to: (a) isolate and characterize new microbial strains that are able to grow in the presence of NFT, (b) investigate the ability of isolates to decompose NFT, and (c) study the impact of NFT on microbial cell properties. As a result, five microbial species were isolated. A 24-h contact of bacteria with NFT provoked modifications in microbial cell properties. The greatest differences were observed in Sphingobacterium thalpophilum P3d, in which a decrease in both total and inner membrane permeability (from 86.7% to 48.3% and from 0.49 to 0.42 µM min⁻¹) as well as an increase in cell surface hydrophobicity (from 28.3% to 39.7%) were observed. Nitrofurantoin removal by selected microbial cultures ranged from 50% to 90% in 28 days, depending on the bacterial strain. Although the isolates were able to decompose the pharmaceutical, its presence significantly affected the bacterial cells. Hence, the environmental impact of NFT should be investigated to a greater extent. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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14 pages, 1399 KiB

Open AccessArticle

Differences in Distribution of Potassium-Solubilizing Bacteria in Forest and Plantation Soils in Myanmar

by Xin Dong, Le Lv, Weijun Wang, Yongzhi Liu, Chunhua Yin, Qianqian Xu, Hai Yan, Jinxia Fu and Xiaolu Liu

Int. J. Environ. Res. Public Health 2019, 16(5), 700; https://doi.org/10.3390/ijerph16050700 - 27 Feb 2019

Cited by 41 | Viewed by 5226

Abstract

Potassium (K) has been recognized as an essential element in intensive agricultural production systems, and deficiency of K usually results in a decrease in crop yields. The utilization of potassium-solubilizing bacteria (KSB) to increase the soluble K content in soil has been regarded [...] Read more.

Potassium (K) has been recognized as an essential element in intensive agricultural production systems, and deficiency of K usually results in a decrease in crop yields. The utilization of potassium-solubilizing bacteria (KSB) to increase the soluble K content in soil has been regarded as a desirable pathway to increase plant yields. Following the inoculation of KSB in the soil, potassium can be released (in the form of K⁺) and consumed by plants. This study aims to investigate and compare the distribution characteristics of potassium-solubilizing bacteria between forest and plantation soils in Myanmar. In this study, 14 KSB strains were isolated from rhizosphere samples collected from forest soil, as well as fertilized rubber tree rhizosphere soil and fertilized bare soil from a plantation. Broadleaf forests with high levels of canopy cover mainly comprised the forest environment, and rubber trees were planted in the plantation environment. The Chao and abundance-based coverage estimator (ACE) indices showed that the microbial abundance of the plantation soil was higher than that of the forest soil. According to the Illumina MiSeq sequencing analysis results, the Shannon index of the forest soil was lower while the Simpson index was higher, which demonstrated that the microbial diversity of the forest soil was higher than that of the plantation soil. Potassium-solubilizing test results showed that the strains E, I, M, and N were the most effective KSB under liquid cultivation conditions. Additionally, KSB only accounted for less than 5.47% of the total bacteria detected in either of the sample types, and the distribution of dominant KSB varied with the soil samples. As another result, the abundance of Pseudomonas spp. in S1 was higher than in S2 and S3, indicating a negative impact on the growth of Pseudomonas in the fertilized rubber tree rhizosphere soil. The significance of our research is that it proves that the increasing use of KSB for restoring soil is a good way to reduce the use of chemical fertilizers, which could further provide a relatively stable environment for plant growth. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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12 pages, 2335 KiB

Open AccessArticle

Isolation and Characterization of a Bacterial Strain Capable of Efficient Berberine Degradation

by Shiyue Liu, Yi Zhang, Ping Zeng, Heli Wang, Yonghui Song and Juan Li

Int. J. Environ. Res. Public Health 2019, 16(4), 646; https://doi.org/10.3390/ijerph16040646 - 21 Feb 2019

Cited by 16 | Viewed by 4243

Abstract

Background: Berberine (BBR) is a pharmaceutical chemical with a broad antibacterial spectrum, and its biological treatment has been of research and practical interest. In this study, a pure bacterial strain B16 was isolated from the activated sludge in a pharmaceutical wastewater treatment plant. [...] Read more.

Background: Berberine (BBR) is a pharmaceutical chemical with a broad antibacterial spectrum, and its biological treatment has been of research and practical interest. In this study, a pure bacterial strain B16 was isolated from the activated sludge in a pharmaceutical wastewater treatment plant. The aim of the study is to characterize the properties of the strain B16, especially its BBR degradation capability. Methods: The identification of strain B16 was conducted by visual observation, as well as biochemical and phylogenetic analysis. The degradation kinetics of strain B16 was tentatively described by Haldane model. Results: The strain B16 was 100% determined as a Sphingopyxis sp. The kinetic parameters of BBR degradation by strain B16 were as follows: Vmax 54.73 ± 5.54 mg (g MLSS · h)⁻¹, Km 66.68 ± 8.95 mg L⁻¹, and Ki 43.16 ± 5.92 mg L⁻¹, with an R² of 0.996. Stain B16 exhibited considerable capability of BBR degradation. BBR of initial concentration 40 mg L⁻¹ could be completely degraded in 48 h under optimal conditions. Conclusions: strain B16 was the first pure culture found with the ability to totally mineralize BBR, indicating the potential of B16 application in real industrial processes. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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Review

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15 pages, 832 KiB

Open AccessReview

Phenomenal Bombardment of Antibiotic in Poultry: Contemplating the Environmental Repercussions

by Muthu Manikandan, Sechul Chun, Zakayo Kazibwe, Judy Gopal, Udai Bhan Singh and Jae-Wook Oh

Int. J. Environ. Res. Public Health 2020, 17(14), 5053; https://doi.org/10.3390/ijerph17145053 - 14 Jul 2020

Cited by 15 | Viewed by 4481

Abstract

Antibiotics have constantly been added at an unprecedented rate in order to enhance poultry meat production. Such antibiotics impose a negative impact on human health directly through meat and egg consumption. On the other hand, they also affect humans indirectly by affecting the [...] Read more.

Antibiotics have constantly been added at an unprecedented rate in order to enhance poultry meat production. Such antibiotics impose a negative impact on human health directly through meat and egg consumption. On the other hand, they also affect humans indirectly by affecting the normal key microbial processes in the agricultural environments, when used as poultry compost. For many years, farmers have been turning poultry litter into compost for agricultural use. Very few studies have addressed the fate of the unmetabolized antibiotic residues in poultry litter that could potentially affect microbial communities when used as poultry compost. We have also questioned the fate of residual antibiotic in poultry waste which may create possible negative environmental pressure on microbial communities that are involved in microbial mediated poultry litter composting processes. The incorporation of antibiotic degrading environmental isolates in poultry litter at the initial stage of composting in order to accelerate the process is addressed in this review as a future perspective. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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27 pages, 2186 KiB

Open AccessReview

Lesson from Ecotoxicity: Revisiting the Microbial Lipopeptides for the Management of Emerging Diseases for Crop Protection

by Deepti Malviya, Pramod Kumar Sahu, Udai B. Singh, Surinder Paul, Amrita Gupta, Abhay Raj Gupta, Shailendra Singh, Manoj Kumar, Diby Paul, Jai P. Rai, Harsh V. Singh and G. P. Brahmaprakash

Int. J. Environ. Res. Public Health 2020, 17(4), 1434; https://doi.org/10.3390/ijerph17041434 - 23 Feb 2020

Cited by 51 | Viewed by 5707

Abstract

Microorganisms area treasure in terms of theproduction of various bioactive compounds which are being explored in different arenas of applied sciences. In agriculture, microbes and their bioactive compounds are being utilized in growth promotion and health promotion withnutrient fortification and its acquisition. Exhaustive [...] Read more.

Microorganisms area treasure in terms of theproduction of various bioactive compounds which are being explored in different arenas of applied sciences. In agriculture, microbes and their bioactive compounds are being utilized in growth promotion and health promotion withnutrient fortification and its acquisition. Exhaustive explorations are unraveling the vast diversity of microbialcompounds with their potential usage in solving multiferous problems incrop production. Lipopeptides are one of such microbial compounds which havestrong antimicrobial properties against different plant pathogens. These compounds are reported to be produced by bacteria, cyanobacteria, fungi, and few other microorganisms; however, genus Bacillus alone produces a majority of diverse lipopeptides. Lipopeptides are low molecular weight compounds which havemultiple industrial roles apart from being usedas biosurfactants and antimicrobials. In plant protection, lipopeptides have wide prospects owing totheirpore-forming ability in pathogens, siderophore activity, biofilm inhibition, and dislodging activity, preventing colonization bypathogens, antiviral activity, etc. Microbes with lipopeptides that haveall these actions are good biocontrol agents. Exploring these antimicrobial compounds could widen the vistasof biological pest control for existing and emerging plant pathogens. The broader diversity and strong antimicrobial behavior of lipopeptides could be a boon for dealing withcomplex pathosystems and controlling diseases of greater economic importance. Understanding which and how these compounds modulate the synthesis and production of defense-related biomolecules in the plants is a key question—the answer of whichneeds in-depth investigation. The present reviewprovides a comprehensive picture of important lipopeptides produced by plant microbiome, their isolation, characterization, mechanisms of disease control, behavior against phytopathogens to understand different aspects of antagonism, and potential prospects for future explorations as antimicrobial agents. Understanding and exploring the antimicrobial lipopeptides from bacteria and fungi could also open upan entire new arena of biopesticides for effective control of devastating plant diseases. Full article

(This article belongs to the Special Issue Microorganisms in the Environment)

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