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Kwak JI, Kim D, An YJ. Evidence of soil particle-induced ecotoxicity in old abandoned mining area. JOURNAL OF HAZARDOUS MATERIALS 2024; 470:134163. [PMID: 38554518 DOI: 10.1016/j.jhazmat.2024.134163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/18/2024] [Accepted: 03/27/2024] [Indexed: 04/01/2024]
Abstract
Ecotoxicity of heavy metals in soil is primarily associated with their bioaccessibility and bioavailability in the soil media. However, in some exceptional cases, soil ecotoxicity has been observed despite high total metal concentrations and low extractable metal concentrations in contaminated field sites; therefore, other exposure pathways must be considered. Therefore, the aim of this study was to evaluate the soil-particle induced ecotoxicity in an old mining area. We hypothesized that heavy metals, strongly adsorbed onto soil particles of consumable size for soil organisms, exhibit ecotoxicity, especially on soil particles ∼1 µm to 300 µm in size. A plant seedling assay, in vivo cytotoxicity assay using earthworm immune cells, and a metal bioconcentration assessment were performed. The results of soil particle toxicity revealed that the soil from the study area (A1-A4) had a low contribution to the soil ecotoxicity of extractable metals. For instance, the concentration of extractable arsenic was only 1.9 mg/kg soil, despite the total arsenic concentration reaching 36,982 mg/kg soil at the A1 site. The qualitative and quantitative analyses using SEM-EDX and ICP-OES, as well as principal component analyses, supported the hypothesis of the present study. Overall, the study results emphasize the importance of soil particle-induced ecotoxicity in long-term contaminated field soils. Our study results can inform on effective site-specific soil ecological risk assessment as they suggest the inclusion of soil particle-induced ecotoxicity as an important criterion in old, contaminated field sites, even when the extractable metal fraction in the field soil is low. ENVIRONMENTAL IMPLICATION: Bioaccessibility and bioavailability are primary factors contributing to the soil ecotoxicity of heavy metals. However, in some cases, such as long-term contaminated field sites, soil ecotoxicity has been confirmed even when low extractable metal concentrations were detected alongside high total metal concentrations. The findings of this study reveal that soil particles of edible size could be sources of soil ecotoxicity in the case of long-term contaminated fields with low extractable metal concentrations. The results of this study would contribute to the area of site-specific soil ecological risk assessment.
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Affiliation(s)
- Jin Il Kwak
- Department of Environmental Health Science, Konkuk University, Seoul 05029, South Korea
| | - Dokyung Kim
- Department of Environmental Health Science, Konkuk University, Seoul 05029, South Korea
| | - Youn-Joo An
- Department of Environmental Health Science, Konkuk University, Seoul 05029, South Korea.
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2
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Cui G, Lü F, Hu T, Zhang H, Shao L, He P. Vermicomposting leads to more abundant microplastics in the municipal excess sludge. CHEMOSPHERE 2022; 307:136042. [PMID: 35981618 DOI: 10.1016/j.chemosphere.2022.136042] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 06/12/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
Municipal excess activated sludge is not only an important reservoir of microplastics particles, but is also a vehicle of entry of microplastics into the environments as soil amendments or organic fertilizer. Vermicomposting is a cost-effective technology for sludge valorization. However, it is not clear whether vermicomposting affects the occurrence of microplastics in residual sludge. Here, the variation of microplastics (0.05-5 mm) in sludge, including the abundance, type, size, and morphology, before and after vermicomposting by epigeic earthworms under different temperature conditions (15 °C, 20 °C and 25 °C) were investigated by micro Fourier Transform Infrared Spectroscopy (μ-FTIR) and Scanning Electronic Microscopy (SEM). More abundant (over 104 particles ∙kg-1 (dry weight)), and smaller microplastics (over 60% in total with 0.05-0.5 mm) in the treated sludge via earthworms were observed compared to the raw sludge. The increment of vermicomposting temperature was more obvious (p < 0.05) for the enrichment of the microplastics, especially for polyethylene particle. Gizzard grinding and microbial digestion in the gut of earthworms may contribute to the fragment of microplastics. The present study suggests that the sludge-sourced vermicompost is still an important hotspot of microplastics, posing a potential threat to the receiving environments.
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Affiliation(s)
- Guangyu Cui
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China; Shanghai Engineering Research Center of Multi-source Solid Wastes Co-processing and Energy Utilization, Shanghai, 200092, China.
| | - Fan Lü
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China; Shanghai Engineering Research Center of Multi-source Solid Wastes Co-processing and Energy Utilization, Shanghai, 200092, China
| | - Tian Hu
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092, China
| | - Hua Zhang
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China; Shanghai Engineering Research Center of Multi-source Solid Wastes Co-processing and Energy Utilization, Shanghai, 200092, China
| | - Liming Shao
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China; Shanghai Engineering Research Center of Multi-source Solid Wastes Co-processing and Energy Utilization, Shanghai, 200092, China
| | - Pinjing He
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China; Shanghai Engineering Research Center of Multi-source Solid Wastes Co-processing and Energy Utilization, Shanghai, 200092, China.
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3
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Earthworms Effect on Microbial Population and Soil Fertility as Well as Their Interaction with Agriculture Practices. SUSTAINABILITY 2022. [DOI: 10.3390/su14137803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Earthworms mix soil layers and bind the soil with organic matter. This combination allows organic matter to disperse through the soil and also allows plants to access the nutrients they retains and enhance the soil’s fertility. Earthworms improve the soil’s biological, chemical, and physical characteristics and serve as soil conditioners. They do so by dissolution, aeration, soil organic breakdown, the release of plant nutrients, and their role in the fastening of nitrogen due to plant growth hormone secretion. However, a variety of soil and environmental factors influence the soil population. Furthermore, it remains uncertain how soil worms modify soil microbial communities’ composition and how they impact the soil’s microbial process. By feeding on microorganisms or selecting and stimulating specific microbial groups, earthworms reduce microbes’ activity and abundance. Earthworms directly impact the plant’s growth and recycling of nutrients but are mainly mediated by indirect microbial community change. Agricultural practices, including the use of pesticides, also contribute to the reduction in soil earthworms. There are no systematic associations among the abundance of earthworms, crop production, and contradictory influence on yield. Earthworms contain hormone-like substances, which encourage the health and growth of plants. This review presents the interaction of earthworms with soil fertility and different agricultural practices, including factors affecting earthworms’ population dynamics in all contexts that enable the adoption of acceptable environmental and earthworms-friendly farming practices for an optimum earthworm, productive, and fertile soil behavior.
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Earthworms drastically change fungal and bacterial communities during vermicomposting of sewage sludge. Sci Rep 2021; 11:15556. [PMID: 34330993 PMCID: PMC8324770 DOI: 10.1038/s41598-021-95099-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 07/14/2021] [Indexed: 01/04/2023] Open
Abstract
Wastewater treatment plants produce hundreds of million tons of sewage sludge every year all over the world. Vermicomposting is well established worldwide and has been successful at processing sewage sludge, which can contribute to alleviate the severe environmental problems caused by its disposal. Here, we utilized 16S and ITS rRNA high-throughput sequencing to characterize bacterial and fungal community composition and structure during the gut- and cast-associated processes (GAP and CAP, respectively) of vermicomposting of sewage sludge. Bacterial and fungal communities of earthworm casts were mainly composed of microbial taxa not found in the sewage sludge; thus most of the bacterial (96%) and fungal (91%) taxa in the sewage sludge were eliminated during vermicomposting, mainly through the GAP. Upon completion of GAP and during CAP, modified microbial communities undergo a succession process leading to more diverse microbiotas than those found in sewage sludge. Consequently, bacterial and fungal community composition changed significantly during vermicomposting. Vermicomposting of sewage resulted in a stable and rich microbial community with potential biostimulant properties that may aid plant growth. Our results support the use of vermicompost derived from sewage sludge for sustainable agricultural practices, if heavy metals or other pollutants are under legislation limits or adequately treated.
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Xiao R, Liu X, Ali A, Chen A, Zhang M, Li R, Chang H, Zhang Z. Bioremediation of Cd-spiked soil using earthworms (Eisenia fetida): Enhancement with biochar and Bacillus megatherium application. CHEMOSPHERE 2021; 264:128517. [PMID: 33049509 DOI: 10.1016/j.chemosphere.2020.128517] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/27/2020] [Accepted: 09/30/2020] [Indexed: 06/11/2023]
Abstract
In this study, we evaluated the influence of biochar and Bacillus megatherium on Cd removal from artificially contaminated soils using earthworms (Eisenia fetida). Within a 35-days remediation period, over 30% of Cd was removed by earthworms from the contaminated soil (with Cd at ∼ 2.5 mg kg-1), and both additives facilitated Cd removal. Additionally, over 22% reduction in the extractable Cd contents was also achieved by earthworms. Cd accumulated in earthworms steadily increased through remediation, and the accumulated Cd decreased in the order of earthworm + biochar (T3) > earthworm + Bacillus megatherium (T4) > earthworm alone (T2). The bioaccumulation factors (BCF) were above 1, indicating the enrichment of Cd in earthworms, and there were higher BCF for both T4 (944%) and T3 (845%). The ingestion of metal-bonded biochar particle and the elevated Cd mobility would be the main reason for the enhanced Cd-remediation by earthworms under T3 and T4, respectively. Through remediation, microbiota communities in both, soil and earthworm guts, demonstrated high similarity, while a lower level of bacterial abundance was observed in earthworm guts compared with that in soils. Eventually, soils became more fertile and demonstrated higher enzyme activities after remediation. Therefore, we concluded that earthworm, alone or combined with biochar or Bacillus megatherium could be an alternative method for Cd-contaminated soil remediation.
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Affiliation(s)
- Ran Xiao
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Xiangyu Liu
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province, 712100, China
| | - Amjad Ali
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province, 712100, China
| | - Anle Chen
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Muyuan Zhang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Ronghua Li
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province, 712100, China
| | - Hong Chang
- College of Resource and Environment, Ningxia University, Yinchuan, 750021, China
| | - Zengqiang Zhang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province, 712100, China.
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Cui G, Bhat SA, Li W, Wei Y, Kui H, Fu X, Gui H, Wei C, Li F. Gut digestion of earthworms significantly attenuates cell-free and -associated antibiotic resistance genes in excess activated sludge by affecting bacterial profiles. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 691:644-653. [PMID: 31326798 DOI: 10.1016/j.scitotenv.2019.07.177] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 07/09/2019] [Accepted: 07/12/2019] [Indexed: 06/10/2023]
Abstract
Vermicomposting can significantly attenuate antibiotic resistance genes (ARGs) in the excess activated sludge (EAS). However, the effect of earthworms, especially the effect of gut digestion as a critical step in the vermicomposting process, remains unclarified. The purpose of this study was to investigate the response of ARGs (cell-free and -associated) in EAS to gut digestion of earthworms and to clarify the possible mechanism from the viewpoint of bacterial community through quantitative polymer chain reaction (q-PCR) and high throughput sequencing. Compared to the initial sludge, the earthworm casts were observed to have significantly lower absolute abundances of ARGs, especially qnrS, tetM, and tetX with the removal exceeding 90%. Cell-free and -associated ARGs (except sul1 and tetG) had equivalent contributions to the attenuation of each ARG. Remarkable reductions of bacterial number and alpha diversity (chao1 and Shannon) were detected in the casts. Spearman correlation analysis between the targeted genes and bacterial community indicates that twelve different phyla mainly including Acidobacteria, Euryarchaeota, Deinococcus-Thermus, Chlorobi, Firmicutes, Fibrobacteres, and Proteobacteria are the potential ARGs hosts, suggesting that the fate and behaviour of these hosts during gut digestion of EAS by earthworms substantially determined the dynamics of the ARGs. These findings increase our understanding of earthworm gut digestion as an important process for the attenuation of ARGs in EAS, and contribute towards preventing their release into the total environment.
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Affiliation(s)
- Guangyu Cui
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China; River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Sartaj Ahmad Bhat
- River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Wenjiao Li
- Graduate School of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Yongfen Wei
- River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Huang Kui
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| | - Xiaoyong Fu
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| | - Hongjie Gui
- School of Environmental Science and Engineering, Tan Kah Kee College, Xiamen University, Zhangzhou 363105, China
| | - Chaohai Wei
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Fusheng Li
- River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
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7
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Bart S, Pelosi C, Barraud A, Péry ARR, Cheviron N, Grondin V, Mougin C, Crouzet O. Earthworms Mitigate Pesticide Effects on Soil Microbial Activities. Front Microbiol 2019; 10:1535. [PMID: 31333628 PMCID: PMC6616067 DOI: 10.3389/fmicb.2019.01535] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 06/20/2019] [Indexed: 11/13/2022] Open
Abstract
Earthworms act synergistically with microorganisms in soils. They are ecosystem engineers involved in soil organic matter degradation and nutrient cycling, leading to the modulation of resource availability for all soil organisms. Using a soil microcosm approach, we aimed to assess the influence of the earthworm Aporrectodea caliginosa on the response of soil microbial activities against two fungicides, i.e., Cuprafor Micro® (copper oxychloride, a metal) and Swing® Gold (epoxiconazole and dimoxystrobin, synthetic organic compounds). The potential nitrification activity (PNA) and soil enzyme activities (glucosidase, phosphatase, arylamidase, and urease) involved in biogeochemical cycling were measured at the end of the incubation period, together with earthworm biomass. Two common indices of the soil biochemistry were used to aggregate the response of the soil microbial functioning: the geometric mean (Gmean) and the Soil Quality Index (SQI). At the end of the experiment, the earthworm biomass was not impacted by the fungicide treatments. Overall, in the earthworm-free soil microcosms, the two fungicides significantly increased several soil enzyme and nitrification activities, leading to a higher GMean index as compared to the non-treated control soils. The microbial activity responses depended on the type of activity (nitrification was the most sensitive one), on the fungicide (Swing® Gold or Cuprafor Micro®), and on the doses. The SQI indices revealed higher effects of both fungicides on the soil microbial activity in the absence of earthworms. The presence of earthworms enhanced all soil microbial activities in both the control and fungicide-contaminated soils. Moreover, the magnitude of the fungicide impact, integrated through the SQI index, was mitigated by the presence of earthworms, conferring a higher stability of microbial functional diversity. Our results highlight the importance of biotic interactions in the response of indicators of soil functioning (i.e., microbial activity) to pesticides.
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Affiliation(s)
- Sylvain Bart
- UMR ECOSYS, INRA, AgroParisTech, Université Paris-Saclay, Versailles, France
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The Contingency of Soil Microorganisms and the Selected Soil Biotic and Abiotic Parameters Under Different Land-Uses. EKOLÓGIA (BRATISLAVA) 2019. [DOI: 10.2478/eko-2019-0008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Land use changes are local phenomena with global impact. They have an impact in a cumulative sense on biodiversity or soil degradation. This study aimed to examine the effects of different land-uses (arable land, permanent grasslands, abandoned grasslands, forest land) on the selected biotic and abiotic soil parameters in the Slovak mountain study sites Liptovská Teplička and Tajov. Biotic (microbial community structure, earthworm number and fresh body biomass, arthropod number and fresh body biomass), and abiotic chemical soil parameters (pH, total organic carbon, total nitrogen, nutrients) were measured. According to MALDI-TOF (Matrix Assisted Laser Desorption Ionization-Time of Flight), several bacterial strains were identified. Mutual relations between soil microorganisms and soil biotic and abiotic properties determined by different land uses were analysed. Microbial response expressed as average well-colour development (AWCD) values indicated relations between higher microbial diversity and higher nutrient availability at both study sites. In the comparison of land use types, permanent grasslands (PG) showed the lowest microbial activity in the depth of 0–0.1 m. But in the depth of 0.2-0.3 m in PG of both study sites, the higher microbial activity was recorded compared to the depth of 0-0.1 m. In addition, lower AWCD values in PG were in line with the lower available P and K content but higher earthworm density and biomass.
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Swati A, Hait S. A Comprehensive Review of the Fate of Pathogens during Vermicomposting of Organic Wastes. JOURNAL OF ENVIRONMENTAL QUALITY 2018; 47:16-29. [PMID: 29415111 DOI: 10.2134/jeq2017.07.0265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Management of both municipal and industrial organic wastes remains a major threat to biota and the environment due to the presence of pathogens in abundance. Vermicomposting employing earthworms is increasingly gaining attention as a sustainable and ecofriendly technique to transform and sanitize a variety of organic wastes into nutrient-rich biofertilizer. Although considerable research has been undertaken to show that vermicomposting can significantly reduce pathogenic contents, there is little effort to summarize the various mechanisms responsible for it. With the aim to assess the fate of pathogens during vermicomposting of various organic wastes, this article provides a comprehensive summary on the occurrence of pathogens in a variety of wastes vis-à-vis pathogens standards, the efficacy of the process for pathogen reduction, and current knowledge of the plausible mechanisms involved. It is evident from the present study that earthworms and endosymbiotic microbes during vermicomposting tend to eliminate pathogens by enhancing enzymatic activities in both gut- and cast-associated processes. Pathogen reduction during vermicomposting can be plausibly attributed to direct actions like microbial inhibition due to intestinal enzymatic action, and secretion of coelomic fluids with antibacterial properties, as well as indirect actions like stimulation of endemic microbes leading to competition and antagonism, and aeration by burrowing activity. Further, the pathogen reduction during vermicomposting is largely selective, and earthworms exert a differential effect according to the earthworm species and whether the pathogen considered is Gram-positive or -negative, owing to its cell wall composition. However, further research is necessary to understand the exact mechanisms involved for pathogen reduction during vermistabilization of municipal and industrial organic wastes.
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Shu Y, Zhang Y, Zeng H, Zhang Y, Wang J. Effects of Cry1Ab Bt maize straw return on bacterial community of earthworm Eisenia fetida. CHEMOSPHERE 2017; 173:1-13. [PMID: 28104475 DOI: 10.1016/j.chemosphere.2017.01.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 06/06/2023]
Abstract
The eco-toxicological effects of Bacillus thuringiensis (Bt) maize on earthworm life-history traits were widely studied and the results were controversial, while their effects on earthworm bacterial community have been rarely studied. Here, effects of two hybrids of Bt maize [5422Bt1 (event Bt11) and 5422CBCL (MON810)] straw return on Eisenia fetida bacterial community were investigated by the terminal restriction fragment length polymorphism (T-RFLP) and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) combing with DNA sequencing, compared to near-isogenic non-Bt maize (5422). Bt maize straw return had significant effects on soil nutrients, especially for available nitrogen (N). The significant differences were shown in soil bacterial community between Bt and non-Bt maize treatments on the 75th and 90th d, which was closely correlated with soil available N, P and K rather than Cry1Ab protein. There was no statistically significant difference in the bacterial community of earthworm gut contents between Bt and non-Bt maize treatments. The significant differences in the bacterial community of earthworm casts were found among three maize varieties treatments, which were closely correlated with Cry1Ab protein and N levels. The differentiated bacterial species in earthworm casts mainly belonged to Proteobacteria, including Brevundimonas, Caulobacter, Pseudomonas, Stenotrophomonas, Methylobacterium, Asticcacaulis and Achromobacter etc., which were associated with the mineralization, metabolic process and degradation of plants residues. Therefore, Bt maize straw return caused changes in the bacterial community of E. fetida casts, which was possibly caused by the direct (Cry1Ab protein) and non-expected effects (N levels) of Bt maize straw.
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Affiliation(s)
- Yinghua Shu
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
| | - Yanyan Zhang
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
| | - Huilan Zeng
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
| | - Yahui Zhang
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
| | - Jianwu Wang
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
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11
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Hussain N, Singh A, Saha S, Venkata Satish Kumar M, Bhattacharyya P, Bhattacharya SS. Excellent N-fixing and P-solubilizing traits in earthworm gut-isolated bacteria: A vermicompost based assessment with vegetable market waste and rice straw feed mixtures. BIORESOURCE TECHNOLOGY 2016; 222:165-174. [PMID: 27718399 DOI: 10.1016/j.biortech.2016.09.115] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 09/23/2016] [Accepted: 09/28/2016] [Indexed: 06/06/2023]
Abstract
Vermicomposting is a dependable waste recycling technology which greatly augments N and P levels mainly through microbial action. This paper aims to identify efficient N-fixing (NFB) and P-solubilizing (PSB) bacteria from earthworm intestines. Various combinations of vegetable market waste, rice straw, and cowdung were fed to two earthworm species (Eisenia fetida and Perionyx excavatus). Total organic C decreased, pH shifted towards neutrality, and NPK availability, and microbial (NFB, PSB, and total bacteria) population increased remarkably during vermicomposting with E. fetida. Therefore, 45 NFB and 34 PSB strains isolated from Eisenia gut were initially screened, their inter-dominance assessed, and 8 prolific strains were identified through 16SrRNA sequencing. Interestingly, two novel N-fixing strains of Kluyvera ascorbata emerged as an efficient biofertilizer candidate. Moreover, both N-fixing and P-solubilizing strains of Serratia and Bacillus were isolated from earthworm gut. All the isolated strains significantly improved soil health and facilitated crop growth as compared to commercial biofertilizers.
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Affiliation(s)
- Nazneen Hussain
- Department of Environmental Science, Tezpur University, Assam 784028, India
| | - Archana Singh
- Department of Molecular Biology and Biotechnology, Tezpur University, Assam 784028, India
| | - Sougata Saha
- Department of Molecular Biology and Biotechnology, Tezpur University, Assam 784028, India
| | | | - Pradip Bhattacharyya
- Agricultural and Ecological Research Unit, Indian Statistical Institute, Giridih, Jharkhand 815301, India
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Yausheva Е, Sizova Е, Lebedev S, Skalny A, Miroshnikov S, Plotnikov A, Khlopko Y, Gogoleva N, Cherkasov S. Influence of zinc nanoparticles on survival of worms Eisenia fetida and taxonomic diversity of the gut microflora. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:13245-54. [PMID: 27023811 DOI: 10.1007/s11356-016-6474-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 03/14/2016] [Indexed: 04/16/2023]
Abstract
The study was conducted to examine the effect of zinc nanoparticles on survival of worms Eisenia fetida and composition of the gut microflora. Analysis of the survival data has shown that the introduction of high doses of the nanoparticles causes death of worms in the second group with 35 % mortality rate and activates protective mechanisms realized as mucous film. DNA from the worm guts was extracted and 16S metagenomic sequencing was fulfilled using MiSeq (Illumina). Regarding the gut microflora of worms in the control group, high diversity of microorganisms (303 OTUs) was noted. Most of those belong to the taxa Firmicutes (51.9 % of the total high-quality united reads), Proteobacteria (24.1 % of the total), and Actinobacteria (13.3 % of the total), which were represented by numerous species of gen. Clostridium (C. saccharobutylicum, C. saccharoperbutylacetonicum, C. beijerinckii), gen. Pseudomonas (P. hydrogenovora, P. aeruginosa, and P. putida), gen. Bacillus (B. megaterium, B. silvestris), gen. Cellulomonas (B. megaterium, B. silvestris), and other numerically smaller genera. Adding of zinc nanoparticles to the substrate decreased the diversity of bacteria (78 OTUs) as well as percentage of bacteria belonging to the taxon Firmicutes (-41.6 %) and increased the proportion of Proteobacteria due to growth in abundance of gen. Verminephrobacter (+46 %) and gen. Ochrobactrum (+19.5 %).
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Affiliation(s)
- Еlena Yausheva
- All-Russian Research Institute of Beef Cattle Breeding, 29, 9-Yanvarya Street, Orenburg, Russia, 460000.
| | - Еlena Sizova
- Orenburg State University, Pobedy pr. 13, Orenburg, Russia, 460018
- All-Russian Research Institute of Beef Cattle Breeding, 29, 9-Yanvarya Street, Orenburg, Russia, 460000
| | - Svyatoslav Lebedev
- Orenburg State University, Pobedy pr. 13, Orenburg, Russia, 460018
- All-Russian Research Institute of Beef Cattle Breeding, 29, 9-Yanvarya Street, Orenburg, Russia, 460000
| | - Anatoliy Skalny
- Orenburg State University, Pobedy pr. 13, Orenburg, Russia, 460018
| | - Sergey Miroshnikov
- All-Russian Research Institute of Beef Cattle Breeding, 29, 9-Yanvarya Street, Orenburg, Russia, 460000
| | - Andrey Plotnikov
- Institute for Cellular and Intracellular Symbiosis UB RAS, 11, Pionerskaya Street, Orenburg, Russia, 460000
| | - Yuri Khlopko
- Institute for Cellular and Intracellular Symbiosis UB RAS, 11, Pionerskaya Street, Orenburg, Russia, 460000
| | - Natalia Gogoleva
- Kazan Institute of Biochemistry and Biophysics RAS, 2/31 Lobachevskogo Street, Kazan, Russia, 420111
| | - Sergey Cherkasov
- Institute for Cellular and Intracellular Symbiosis UB RAS, 11, Pionerskaya Street, Orenburg, Russia, 460000
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Wang Y, Xing MY, Yang J, Lu B. Addressing the role of earthworms in treating domestic wastewater by analyzing biofilm modification through chemical and spectroscopic methods. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:4768-4777. [PMID: 26538257 DOI: 10.1007/s11356-015-5661-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 10/20/2015] [Indexed: 06/05/2023]
Abstract
Vermifiltration eco-friendly system is an alternative and low-cost artificial ecosystem for decentralized wastewater treatment and excess sludge reduction. The biofilm characteristics of a vermifilter (VF) with earthworms, Eisenia fetida, for domestic wastewater treatment were studied. A conventional biofilter (BF) without earthworms served as the control. Pore number in VF biofilm was significantly more than BF biofilm, and VF biofilm showed a better level-administrative structure through scanning electron microscope. VF biofilms had lower levels of protein and polysaccharide, but phosphoric acids and humic acid showed the opposite results. Furthermore, in the presence of earthworms, VF biofilms contained higher total organic carbon (TOC) percentage composition in the condition of less volatile suspended substances (VSS) contents. Dehydrogenase activity (DHA) and adenosine triphosphate (ATP) contents along VF showed better results than BF by increment of 12.84 ∼ 16.46 %. Overall findings indicated that the earthworms' presence remarkably decreases biofilm contests but increases enzyme activity and improves the community structure of VF biofilms, which is beneficial for the wastewater disposal.
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Affiliation(s)
- Yin Wang
- Key Laboratory of Yangtze Water Environment for Ministry of Education, State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Mei-Yan Xing
- Key Laboratory of Yangtze Water Environment for Ministry of Education, State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
| | - Jian Yang
- Key Laboratory of Yangtze Water Environment for Ministry of Education, State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Biao Lu
- Key Laboratory of Yangtze Water Environment for Ministry of Education, State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
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Fu X, Cui G, Huang K, Chen X, Li F, Zhang X, Li F. Earthworms facilitate the stabilization of pelletized dewatered sludge through shaping microbial biomass and activity and community. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:4522-4530. [PMID: 26514568 DOI: 10.1007/s11356-015-5659-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 10/20/2015] [Indexed: 06/05/2023]
Abstract
In this study, the effect of earthworms on microbial features during vermicomposting of pelletized dewatered sludge (PDS) was investigated through comparing two degradation systems with and without earthworm E isenia fetida involvement. After 60 days of experimentation, a relatively stable product with low organic matter and high nitrate and phosphorous was harvested when the earthworms were involved. During the process, earthworms could enhance microbial activity and biomass at the initial stage and thus accelerating the rapid decomposition of PDS. The end products of vermicomposting allowed the lower values of bacterial and eukaryotic densities comparison with those of no earthworm addition. In addition, the presence of earthworms modified the bacterial and fungal diversity, making the disappearances of some pathogens and specific decomposing bacteria of recalcitrant substrates in the vermicomposting process. This study evidences that earthworms can facilitate the stabilization of PDS through modifying microbial activity and number and community during vermicomposting.
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Affiliation(s)
- Xiaoyong Fu
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, China.
| | - Guangyu Cui
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, China
| | - Kui Huang
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, China.
- River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
| | - Xuemin Chen
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, China
| | - Fusheng Li
- River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | - Xiaoyu Zhang
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, China
| | - Fei Li
- School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, China
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15
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Lv B, Xing M, Yang J, Zhang L. Pyrosequencing reveals bacterial community differences in composting and vermicomposting on the stabilization of mixed sewage sludge and cattle dung. Appl Microbiol Biotechnol 2015; 99:10703-12. [PMID: 26318447 DOI: 10.1007/s00253-015-6884-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 07/22/2015] [Accepted: 07/26/2015] [Indexed: 10/23/2022]
Abstract
This study aimed to compare the microbial community structures and compositions in composting and vermicomposting processes. We applied 454 high-throughput pyrosequencing to analyze the 16S rRNA gene of bacteria obtained from bio-stabilization of sewage sludge and cattle dung. Results demonstrated that vermicomposting process presented higher operational taxonomic units and bacterial diversity than the composting. Analysis using weighted UniFrac indicated that composting exhibited higher effects on shaping microbial community structure than the vermicomposting. The succession of dominant bacteria was also detected during composting. Firmicutes was the dominant bacteria in the thermophilic phase of composting and shifted to Actinomycetes in the maturing stage. By contrast, Proteobacteria accounted for the highest proportions in the whole process of the vermicomposting. Furthermore, vermicomposting contained more uncultured and unidentified bacteria at the taxonomy level of genus than the composting. In summary, the bacterial community during composting significantly differed from that during vermicomposting. These two techniques played different roles in changing the diversity and composition of microbial communities.
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Affiliation(s)
- Baoyi Lv
- College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai, 201306, China.,Institute of Biofilm Technology, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Meiyan Xing
- Institute of Biofilm Technology, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
| | - Jian Yang
- Institute of Biofilm Technology, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Liangbo Zhang
- College of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou, 450001, China
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17
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Suthar S, Sajwan P, Kumar K. Vermiremediation of heavy metals in wastewater sludge from paper and pulp industry using earthworm Eisenia fetida. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 109:177-184. [PMID: 25215882 DOI: 10.1016/j.ecoenv.2014.07.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 07/08/2014] [Accepted: 07/24/2014] [Indexed: 06/03/2023]
Abstract
This work presents the results of removing heavy metals from paper mill wastewater (PMS) sludge spiked with cow dung (CD) employing Eisenia fetida. A total of seven set-ups were prepared: CD (100 percent), PMS: CD (1:3), PMS:CD (1:2), PMS:CD (1:1), PMS (100 percent), PMS:CD (3:1) and PMS:CD (2:1) and changes in chemical parameters were observed for 60 days. Vermistabilization caused the significant decrease in the level of Cd (32-37 percent), Cr (47.3-80.9 percent), Cu (68.8-88.4 percent), and Pb (95.3-97.5 percent) and substantial increase in EC, total-N, available P and K at the end. At the end, the tissues of inoculated worms showed the high load (mg kg(-1), dry biomass) of Pb (8.81-9.69), Cd (2.31-2.71), Cr (20.7-35.9) and Cu (9.94-11.6), respectively which indicated bioaccumulation of metals by worms. The PMS:CD (2:1 and/or 3:1) appeared to be suitable waste mixture in terms of high metal removal and earthworm growth rates. Bioaccumulation, as quantified using BCF, was in the order: Cd>Cr>Pb>Cu. Results suggested vermiremediation as appropriate technology for bioremediation of heavy metals from PMS.
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Affiliation(s)
- Surindra Suthar
- School of Environment & Natural Resources, Doon University, Dehradun-248001, India.
| | - Poonam Sajwan
- School of Environment & Natural Resources, Doon University, Dehradun-248001, India
| | - Kapil Kumar
- School of Environment & Natural Resources, Doon University, Dehradun-248001, India
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18
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Depkat-Jakob PS, Brown GG, Tsai SM, Horn MA, Drake HL. Emission of nitrous oxide and dinitrogen by diverse earthworm families from Brazil and resolution of associated denitrifying and nitrate-dissimilating taxa. FEMS Microbiol Ecol 2012; 83:375-91. [DOI: 10.1111/j.1574-6941.2012.01476.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 07/31/2012] [Accepted: 08/17/2012] [Indexed: 11/30/2022] Open
Affiliation(s)
| | | | - Siu M. Tsai
- Center for Nuclear Energy in Agriculture; University of São Paulo; São Paulo; Brazil
| | - Marcus A. Horn
- Department of Ecological Microbiology; University of Bayreuth; Bayreuth; Germany
| | - Harold L. Drake
- Department of Ecological Microbiology; University of Bayreuth; Bayreuth; Germany
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Species-specific effects of epigeic earthworms on microbial community structure during first stages of decomposition of organic matter. PLoS One 2012; 7:e31895. [PMID: 22363763 PMCID: PMC3283695 DOI: 10.1371/journal.pone.0031895] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 01/19/2012] [Indexed: 11/19/2022] Open
Abstract
Background Epigeic earthworms are key organisms in organic matter decomposition because of the interactions they establish with microorganisms. The earthworm species and the quality and/or substrate availability are expected to be major factors influencing the outcome of these interactions. Here we tested whether and to what extent the epigeic earthworms Eisenia andrei, Eisenia fetida and Perionyx excavatus, widely used in vermicomposting, are capable of altering the microbiological properties of fresh organic matter in the short-term. We also questioned if the earthworm-induced modifications to the microbial communities are dependent on the type of substrate ingested. Methodology/Principal Findings To address these questions we determined the microbial community structure (phospholipid fatty acid profiles) and microbial activity (basal respiration and microbial growth rates) of three types of animal manure (cow, horse and rabbit) that differed in microbial composition, after being processed by each species of earthworm for one month. No differences were found between earthworm-worked samples with regards to microbial community structure, irrespective of type of manure, which suggests the existence of a bottleneck effect of worm digestion on microbial populations of the original material consumed. Moreover, in mesocosms containing cow manure the presence of E. andrei resulted not only in a decrease in bacterial and fungal biomass, but also in a reduced bacterial growth rate and total microbial activity, while no such reduction was found with E. fetida and P. excavatus. Conclusions/Significance Our results point to the species of earthworm with its associated gut microbiota as a strong determinant of the process shaping the structure of microbial communities in the short-term. This must nonetheless be weighed against the fact that further knowledge is necessary to evaluate whether the changes in the composition of microbiota in response to the earthworm species is accompanied by a change in the microbial community diversity and/or function.
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Epigeic earthworms exert a bottleneck effect on microbial communities through gut associated processes. PLoS One 2011; 6:e24786. [PMID: 21935465 PMCID: PMC3174214 DOI: 10.1371/journal.pone.0024786] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 08/17/2011] [Indexed: 12/05/2022] Open
Abstract
Background Earthworms play a critical role in organic matter decomposition because of the interactions they establish with microorganisms. The ingestion, digestion, assimilation of organic material in the gut and then casting is the first step in earthworm-microorganism interactions. The current knowledge of these direct effects is still limited for epigeic earthworm species, mainly those living in man-made environments. Here we tested whether and to what extent the earthworm Eisenia andrei is capable of altering the microbiological properties of fresh organic matter through gut associated processes; and if these direct effects are related to the earthworm diet. Methodology To address these questions we determined the microbial community structure (phospholipid fatty acid profiles) and microbial activity (fluorescein diacetate hydrolysis) in the earthworm casts derived from three types of animal manure (cow, horse and pig manure), which differed in microbial composition. Principal Findings The passage of the organic material through the gut of E. andrei reduced the total microbial biomass irrespective of the type of manure, and resulted in a decrease in bacterial biomass in all the manures; whilst leaving the fungi unaffected in the egested materials. However, unlike the microbial biomass, no such reduction was detected in the total microbial activity of cast samples derived from the pig manure. Moreover, no differences were found between cast samples derived from the different types of manure with regards to microbial community structure, which provides strong evidence for a bottleneck effect of worm digestion on microbial populations of the original material consumed. Conclusions/Significance Our data reveal that earthworm gut is a major shaper of microbial communities, thereby favouring the existence of a reduced but more active microbial population in the egested materials, which is of great importance to understand how biotic interactions within the decomposer food web influence on nutrient cycling.
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Gómez-Brandón M, Aira M, Lores M, Domínguez J. Changes in microbial community structure and function during vermicomposting of pig slurry. BIORESOURCE TECHNOLOGY 2011; 102:4171-4178. [PMID: 21220200 DOI: 10.1016/j.biortech.2010.12.057] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 12/10/2010] [Accepted: 12/14/2010] [Indexed: 05/30/2023]
Abstract
Most studies investigating the effects of earthworms on microorganisms have focused on the changes before and after vermicomposting rather than those that occur throughout the process. In the present study, we designed continuous feeding reactors in which new layers of pig slurry (1.5 and 3 kg) were added sequentially to form an age gradient inside the reactors in order to evaluate the impact of the earthworm species Eisenia fetida on microbial community structure and function. The activity of earthworms greatly reduced the bacterial and fungal biomass and microbial diversity relative to the control values. However, the pronounced presence of earthworms in the younger layers stimulated microbial activity and as such increased carbon mineralization probably due to the fact that the microorganisms may have been less resource-limited as a result of earthworm activity, as indicated by the ratio of monounsaturated to saturated PLFAs.
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Affiliation(s)
- María Gómez-Brandón
- Departamento de Ecología y Biología Animal, Universidade de Vigo, E-36310 Vigo, Spain.
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Aira M, Domínguez J. Earthworm effects without earthworms: inoculation of raw organic matter with worm-worked substrates alters microbial community functioning. PLoS One 2011; 6:e16354. [PMID: 21298016 PMCID: PMC3029341 DOI: 10.1371/journal.pone.0016354] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 12/20/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Earthworms are key organisms in organic matter decomposition because of the interactions they establish with soil microorganisms. They enhance decomposition rates through the joint action of direct effects (i.e. effects due to direct earthworm activity such as digestion, burrowing, etc) and indirect effects (i.e. effects derived from earthworm activities such as cast ageing). Here we test whether indirect earthworm effects affect microbial community functioning in the substrate, as when earthworms are present (i. e., direct effects). METHODOLOGY/PRINCIPAL FINDINGS To address these questions we inoculated fresh organic matter (pig manure) with worm-worked substrates (vermicompost) produced by three different earthworm species. Two doses of each vermicompost were used (2.5 and 10%). We hypothesized that the presence of worm-worked material in the fresh organic matter will result in an inoculum of different microorganisms and nutrients. This inoculum should interact with microbial communities in fresh organic matter, thus promoting modifications similar to those found when earthworms are present. Inoculation of worm-worked substrates provoked significant increases in microbial biomass and enzyme activities (β-glucosidase, cellulase, phosphatase and protease). These indirect effects were similar to, although lower than, those obtained in pig manure with earthworms (direct and indirect earthworm effects). In general, the effects were not dose-dependent, suggesting the existence of a threshold at which they were triggered. CONCLUSION/SIGNIFICANCE Our data reveal that the relationships between earthworms and microorganisms are far from being understood, and suggest the existence of several positive feedbacks during earthworm activity as a result of the interactions between direct and indirect effects, since their combination produces stronger modifications to microbial biomass and enzyme activity.
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Affiliation(s)
- Manuel Aira
- Departamento de Ecoloxía e Bioloxía Animal, Facultade de Bioloxía, Universidade de Vigo, Vigo, Spain.
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Depkat-Jakob PS, Hilgarth M, Horn MA, Drake HL. Effect of earthworm feeding guilds on ingested dissimilatory nitrate reducers and denitrifiers in the alimentary canal of the earthworm. Appl Environ Microbiol 2010; 76:6205-14. [PMID: 20656855 PMCID: PMC2937516 DOI: 10.1128/aem.01373-10] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 07/19/2010] [Indexed: 11/20/2022] Open
Abstract
The earthworm gut is an anoxic nitrous oxide (N(2)O)-emitting microzone in aerated soils. In situ conditions of the gut might stimulate ingested nitrate-reducing soil bacteria linked to this emission. The objective of this study was to determine if dissimilatory nitrate reducers and denitrifiers in the alimentary canal were affected by feeding guilds (epigeic [Lumbricus rubellus], anecic [Lumbricus terrestris], and endogeic [Aporrectodea caliginosa]). Genes and gene transcripts of narG (encodes a subunit of nitrate reductase and targets both dissimilatory nitrate reducers and denitrifiers) and nosZ (encodes a subunit of N(2)O reductase and targets denitrifiers) were detected in guts and soils. Gut-derived sequences were similar to those of cultured and uncultured soil bacteria and to soil-derived sequences obtained in this study. Gut-derived narG sequences and narG terminal restriction fragments (TRFs) were affiliated mainly with Gram-positive organisms (Actinobacteria). The majority of gut- and uppermost-soil-derived narG transcripts were affiliated with Mycobacterium (Actinobacteria). In contrast, narG sequences indicative of Gram-negative organisms (Proteobacteria) were dominant in mineral soil. Most nosZ sequences and nosZ TRFs were affiliated with Bradyrhizobium (Alphaproteobacteria) and uncultured soil bacteria. TRF profiles indicated that nosZ transcripts were more affected by earthworm feeding guilds than were nosZ genes, whereas narG transcripts were less affected by earthworm feeding guilds than were narG genes. narG and nosZ transcripts were different and less diverse in the earthworm gut than in mineral soil. The collective results indicate that dissimilatory nitrate reducers and denitrifiers in the earthworm gut are soil derived and that ingested narG- and nosZ-containing taxa were not uniformly stimulated in the guts of worms from different feeding guilds.
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Affiliation(s)
- Peter S. Depkat-Jakob
- Department of Ecological Microbiology, University of Bayreuth, 95440 Bayreuth, Germany
| | - Maik Hilgarth
- Department of Ecological Microbiology, University of Bayreuth, 95440 Bayreuth, Germany
| | - Marcus A. Horn
- Department of Ecological Microbiology, University of Bayreuth, 95440 Bayreuth, Germany
| | - Harold L. Drake
- Department of Ecological Microbiology, University of Bayreuth, 95440 Bayreuth, Germany
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