Aquaculture effluents are major sources of nutrient and organic pollution, making their treatment a critical research priority. This study evaluated the performance of a natural in-situ algae-bacteria consortia in treating two types of aquaculture wastewater (soft-shelled turtle effluent and aquacultural sludge wastewater). After 7 days, the consortia achieved high removal efficiencies in turtle effluent, 93.5 % for ammonium nitrogen (NH4+- N), 82.6 % for total nitrogen (TN), and 70.6 % for chemical oxygen demand (COD). In sludge wastewater, removal efficiencies reached 77.1 % for NH4+-N, 87.1 % for TN, 91.7 % for COD, and 89.0 % for total phosphorus (TP), outperforming non-algal controls by 25-45 %. Microbial community analyses revealed a shift toward Chlorella dominant algal populations and a transition from fermentative bacterial taxa (e.g. Clostridium) to aerobic groups such as Pseudomonas and Acinetobacter, supporting enhanced nutrient transformations. Redundancy analysis (RDA) and canonical correspondence analysis (CCA) showed that nutrient variables explained over 58 % of community variation, with NH4+-N and TP strongly correlated with Clostridium and Ruminiclostridium, and TN and NO3--N associated with Chloroplast, Mitochondria. Mantel tests and random forest analyses identified Chloroplast, Clostridium, Ruminiclostridium, and norank_o_Veillonellales-Selenomonadales as robust biomarkers. These findings demonstrate that algae-bacteria consortia effectively reduce pollutants in aquaculture effluents through synergistic restructuring of microbial communities, offering a scalable strategy for sustainable wastewater management.

Mine wastewater pollution, primarily caused by heavy metals and sulfates, poses a significant threat to ecosystems and water quality in mining-affected regions. Effective remediation is essential for mitigating these environmental impacts and ensuring sustainable water management. This study explores the potential of bio-modified coal gangue (MCG) as a sustainable solution for remediating mine wastewater. Bio-modification significantly improved the gangue's physicochemical properties, enhancing its adsorption capacity for both sulfates and heavy metals. Sulfate removal was primarily driven by microbial activity, with sulfate-reducing bacteria (SRB) in activated sludge and mine water producing removal efficiencies of up to 58.49%. Heavy metals, including mercury, antimony, copper, and arsenic, were effectively reduced to levels meeting regulatory standards, though additional treatment is required for zinc. Key factors influencing performance included temperature, pH, and particle size, with SRB-modified gangue in activated sludge demonstrating superior adaptability and stability across varying conditions. SEM analysis confirmed that bio-modification introduced surface roughness, porosity, and active sites essential for pollutant adsorption. These findings highlight the dual benefits of MCG in addressing wastewater treatment and coal gangue utilization, offering an innovative, cost-effective, and environmentally sustainable approach to mine wastewater remediation.

Extracellular polymeric substances (EPS) play a vital role in forming microbial aggregates such as biofilms, flocs, and granules. However, standardised methods for extracting EPS from the activated sludge across different wastewater treatment processes remain elusive. The anaerobic-anoxic-oxic (A2O) process, widely used in wastewater treatment, was selected to investigate EPS extraction from its activated sludge. This study compared twenty-five physicochemical methods for EPS extraction from the activated sludge collected from the secondary sedimentation basin of an A2O reactor, evaluating EPS yield, composition, and cell lysis. The results show that combined chemical-physical extraction methods, particularly NaOH/heat treatment, achieved higher extraction rates while preserving EPS characteristics. This method yielded higher concentrations of proteins (PN) and polysaccharides (PS) with reduced cell lysis compared to other techniques. In most methods, protein content exceeded polysaccharides content, with PN/PS ratios ranging from 0.005 to 4.17 g/g. Higher PN/PS ratios were associated with smoother, more uniform EPS morphology. Particle size distribution of the treated sludge showed minimal variation between methods. Fourier transform infrared (FTIR) and excitation emission matrix (EEM) fluorescence spectroscopy confirmed the presence of proteins, polysaccharides, and DNA in EPS, with NaOH/heat treatment more effectively preserving functional groups. Optimisation tests identified 45 min as the ideal heating duration for maximum EPS extraction. Overall, this study provides a systematic evaluation of EPS extraction methods from the activated sludge in A2O systems, offering methodological insights for future wastewater treatment research.

Aquaculture sediments are important sinks for heavy metals (HMs), with implications for microbial activity and ecological health. This study investigated the concentrations, ecological risks, and biochemical impacts of HMs in fish pond sediments (FPS) and shrimp field sediment (SFS) from the Jianghan Plain, China. The sediments exhibited contrasting textures, with FPS dominated by sandy loam (80 %) and SFS by silty loam (67 %). Eight heavy metals, As, Cd, Ba, Co, Cr, Cu, Ni and Pb, were quantified, with Cd presenting the most severe contamination. Cd concentrations averaged 1.8 mg & sdot;kg-1 in FPS and 3.8 mg & sdot;kg-1 in SFS, exceeding the Chinese regulatory threshold (0.5 mg & sdot;kg-1) by 3.6- and 7.6-fold, respectively. Pollution load index (PLI) values indicated moderate contamination across all samples (PLItype(FPS) = 1.725; PLItype(SFS) = 1.723), whereas potential ecological risk index (PER) assessments revealed severe risk in FPS (mean PER=434) and extremely high risk in SFS (mean PER=885), with Cd alone contributing over 90 % of the total risk. Variance partitioning analysis (VPA) attributed 76.9 % of the variation in enzymatic activities to heavy metals, compared to 13.0 % from physicochemical parameters. Redundancy analysis (RDA) and the partial Mantel test pointed out that Cd, Cu, and Ba were identified as the primary inhibitors of sediment enzyme activities, with urease and neutral phosphatase most strongly affected by Cd, and cellulase and sucrase suppressed by Ba and Cu. Multiple linear regression modeling identified urease activity as a robust ecological indicator, showing a strong predictive relationship with HM pollution (adjusted R2 = 0.916, P < 0.001). These findings underscore the dominant role of Cd in driving ecological risk and enzymatic disruption in aquaculture sediments and support the use of urease as a sensitive biomarker for sediment quality monitoring in freshwater aquaculture systems.

Pathogenic bacteria, the major causative agents of aquaculture diseases, are a serious impediment to the aquaculture industry. However, the bioinformatics of pathogenic bacteria and virulence factors (VFs) in sediments, an important component of freshwater aquaculture ecosystems, are not well characterized. In this study, 20 sediment samples were collected from fish pond sediments (FPS), shrimp field sediments (SFS), fish pond sediment control (FPSC), and shrimp field sediment control (SFSC). Molecular biological information was obtained on a total of 173 pathogenic bacteria, 1093 virulence factors (VFs), and 8475 mobile genetic elements (MGEs) from these samples. The results indicated that (1) aquaculture patterns and sediment characteristics can affect the distribution of pathogenic bacteria. According to the results of the Kruskal–Wallis H test, except for Mycobacterium gilvum , there were significant differences ( P < 0.05) among the four sediment types in the average abundance of major pathogenic bacteria (top 30 in abundance), and the average abundance of major pathogenic bacteria in the four sediment types followed the following pattern: FPS > SFS > FPSC > SFSC. (2) Pathogenic bacteria are able to implement a variety of complex pathogenic mechanisms such as adhesion, invasion, immune evasion, and metabolic regulation in the host because they carry a variety of VFs such as type IV pili , HSI-I , Alginate , Colibactin , and Capsule . According to the primary classification of the Virulence Factor Database (VFDB), the abundance of VFs in all four types of sediments showed the following pattern: offensive VFs > non-specific VFs > defensive VFs > regulation of virulence-related genes. (3) Total organic carbon (TOC), total phosphorus (TP), available phosphorus (AP), nitrite, and nitrate were mostly only weakly positively correlated with the major pathogenic bacteria and could promote the growth of pathogenic bacteria to some extent, whereas ammonia was significantly positively correlated with most of the major pathogenic bacteria and could play an important role in promoting the growth and reproduction of pathogenic bacteria. (4) Meanwhile, there was also a significant positive correlation between CAZyme genes and major pathogenic bacteria (0.62 ≤ R ≤ 0.89, P < 0.05). This suggests that these pathogenic bacteria could be the main carriers of CAZyme genes and, to some extent, gained a higher level of metabolic activity by degrading organic matter in the sediments to maintain their competitive advantage. (5) Worryingly, the results of correlation analyses indicated that MGEs in aquaculture sediments could play an important role in the spread of VFs ( R = 0.82, P < 0.01), and in particular, plasmids ( R = 0.75, P < 0.01) and integrative and conjugative elements (ICEs, R = 0.65, P < 0.05) could be these major vectors of VFs. The results of this study contribute to a comprehensive understanding of the health of freshwater aquaculture sediments and provide a scientific basis for aquaculture management and conservation.

目前微生物菌剂与表面活性剂、絮凝剂等的复配研究已取得初步进展,且复配效果良好,但微生物菌剂与化学除磷剂的复配研究较少.以微生物菌剂和除磷剂为研究对象,采用响应面法(RSM)中的Box-Behnken设计实验,研究两种试剂的投加量和水体pH对黑臭废水的氨氮(NH3-N)、总磷(TP)、化学需氧量(COD)的去除效果,以优化其复配比例.实验结果表明,当清水一 号微生物用量为44.77 mg/L、除磷剂用量为100.29 mg/L、pH为7.72 时,黑臭水体中NH3-N,TP,COD去除效果最佳,此时,NH3-N去除率为57.96%,TP去除率为98.88%,COD去除率为91.89%.此研究可为复合微生物除磷剂这一 新型水处理产品的研制提供相应的实验数据和理论支撑.

Natural biofilms, which are widely distributed in various aquatic environments, can not only serve as bioindicators of various anthropogenic contaminants but also participate in the purification and degradation of various pollutants. However, the inherent purification capacity of natural biofilms and their physiochemical and biological properties are still poorly understood. In this study, outdoor sampling and indoor experiments were used to explore the purification abilities of natural biofilms. The physiochemical and biological properties of natural biofilms were further investigated to reveal their purification mechanism. The results demonstrated that natural biofilms had an excellent purification effect on heavily polluted water. Indoor experiments showed that the purification capacity of natural biofilms was dominated by microbial biodegradation rather than physical biosorption, and after 14.0 days of incubation, the removal rates of COD, TP, NH4+-N, and NO3--N could reach 93.6, 80.83, 85.93, and 81.03%, respectively. The SEM, FTIR spectra, and component analyses revealed that natural biofilms were mainly composed of polysaccharides and proteins. The dominant phyla in the bacterial community structure were Campilobacterota, Proteobacteria, Bacteroidota, Firmicutes, and Desulfobacterota, and the major phyla in the fungal community structure were Chytridiomycota and Ascomycota. These microorganisms might be the main degraders of riverine pollutants.

相对于人为施用的化肥、农药、抗生素及饲料等会污染养殖环境,导致养殖生态系统失衡,损害水产养殖健康发展,微生物菌肥具有改善养殖环境、提高水产养殖动物产量的作用.然而,微生物菌肥对养殖底泥中重金属含量和微生物群落结构及功能的影响仍未知.通过测定施加微生物菌肥前后养殖底泥的理化特性、重金属含量、细菌和真菌微生物群落结构及功能等,深刻剖析微生物菌肥对养殖底泥中重金属含量和微生物群落及功能的影响.结果表明:施加微生物菌肥后养殖底泥中有机质、氨氮、有效磷和总磷等营养化合物含量均有所下降;施加微生物菌肥前养殖底泥中重金属锰、砷、铜、汞和镉的含量均超过中国土壤重金属背景值,施加微生物菌肥后底泥中这五种重金属的含量分别下降了 22.81％、11.93％、22.73％、20.84％和18.00％,并能使底泥中锰、铜和镉的含量恢复到正常水平;施加微生物菌肥前后养殖底泥中微生物群落结构及功能具有明显的差异,施加微生物菌肥后底泥中Chloroflexi,Proteobacteria,Firmicutes等能诱发河道水华、黑臭和耐重金属细菌的丰度下降了 10.41％～34.01％,Chytridiomycota、Ascomycota 和 Basidiomycota 等致病真菌的丰度降低了 77.21％～88.79％.可见,微生物菌肥能有效改善水生态系统平衡和养殖环境,降低水产养殖产品的发病概率,该研究结果可为水产养殖生态修复治理提供理论依据.

The black-odor phenomenon has been widely reported worldwide and recognized as a global ecological risk for aquatic environments. However, driving factors for black-odor-related microorganisms and potential self-remediation strategies are still poorly understood. This study collected eight water samples (sites A–H) disturbed by different factors from the Jishan River located in Jinmen, Hubei Province, China. Black-odor-related environmental factors and functional bacterial structure were further measured based on the basic physicochemical parameters. The results indicated that different types of disturbed conditions shape the distribution of water quality and microbial community structures. Site B, which was disturbed by dams, had the worst water quality, the lowest abundance of functional microbes for Mn, Fe, and S biotransformation, and the highest abundance of functional microbes for fermentation. The natural wetlands surrounding the terminus of the river (site H) were keys to eliminating the black-odor phenomenon. Potential black-odor-forming microorganisms include Lactococcus, Veillonella, Clostridium sensu stricto, Trichococcus, Rhodoferax, Sulfurospirillum, Desulfobulbus, and Anaeromusa-Anaeroarcus. Potential black-odor-repairing microbes include Acinetobacter, Mycobacterium, and Acidovorax. pH and COD were paramount physiochemical factors contributing to blackening-odor-related microorganisms. This study deepens our understanding of driving factors for black-odor-related microorganisms and provides a theoretical basis for eradicating the black-odor phenomenon.

Microbial sulfate reduction, a vital mechanism for microorganisms living in anaerobic, sulfate-rich environments, is an essential aspect of the sulfur biogeochemical cycle. However, there has been no detailed investigation of the diversity and biogenesis contribution of sulfate-reducing bacteria in arsenic-contaminated soils from realgar deposits. To elucidate this issue, soil samples from representative abandoned realgar deposits were collected. Microcosm assays illustrated that all three samples (2–1, 2–2, and 2–3) displayed efficient sulfate and As(V)-respiring activities. Furthermore, a total of 28 novel sequence variants of dissimilatory sulfite reductase genes and 2 new families of dsrAB genes were successfully identified. A novel dissimilatory sulfate-reducing bacterium, Desulfotomaculum sp. JL1, was also isolated from soils, and can efficiently respiratory reduce As(V) and sulfate in 4 and 5 days, respectively. JL1 can promote the generation of yellow precipitates in the presence of multiple electron acceptors (both contain sulfate and As(V) in the cultures), which indicated the biogenesis contribution of sulfate-reducing bacteria to the realgar mine. Moreover, this area had unique microbial communities; the most abundant populations belonged to the phyla Proteobacteria, Chloroflexi, and Acidobacteriota, which were attributed to the unique geochemistry characteristics, such as total organic carbon, total As, NO3−, and SO42−. The results of this study provide new insight into the diversity and biogenesis contributions of sulfate-reducing bacteria in arsenic-contaminated soils from realgar deposits.

Aquaculture sediments have been widely recognized as sinks and sources of heavy metals. Enzyme activities are extremely sensitive to heavy metals contamination and have been indicators to reflect ecological health of terrestrial ecosystems. However, the effects of HMs on enzyme activities and reliable ecological indices for evaluating environmental quality and health in aquacultural sediments are still unknown. In this study, a total of 19 mixed samples of aquaculture sediments were obtained from 9 fish ponds and 10 shrimp fields. The enzyme activities (urease, sucrase, catalase, cellulase and neutral phosphatase), heavy metals (As, Cd, Ba, Co, Cr, Cu, Ni and Pb, etc.) and other physicochemical properties (particle size, pH, TOC, TS and TP, etc.) of aquaculture sediments in Gongan County in the middle reaches of the Yangtze River were studied. The results showed that the texture, organic matter and Cd content in these two kinds of sediments were significantly different. The pollution load index (PLI) evaluation showed that the heavy metal pollution status of these two types of sediments was at the middle level. Variance partition analysis (VPA) showed that heavy metals had a more significant effect on enzyme activities than other parameters. Redundancy analysis (RDA) and the partial Mantel test pointed out that Cd, Cu and Ba were the primary metal elements affecting the enzyme activity of aquaculture sediments, urease and neutral phosphatase activities were significantly inhibited by Cd, while sucrase activity showed a negative correlation with Cu and Ba. The aquaculture sediment quality diagnosis model established by urease has reliable popularizing value (R2 adj=0.916, p<0.001). This in-depth study on the effects of heavy metals on enzyme activities and the establishment of bioindicators provide new perspectives and strategies for environmental monitoring, pollution prevention and ecological management.

Natural rivers have always been invaded by multiple pollutants discharged by anthropogenic activities, inducing physiochemical and biological changes to waterbodies. However, the effects of different types of anthropogenic disturbances and natural wetlands on water quality and bacterial communities in black-odor rivers remain largely unknown. In this study, 13 water quality parameters at 48 sampling sites along the typical contaminated Jishan River were selected to evaluate water quality through water quality index (WQI). The analysis of microbial community composition and its correlation with water quality of different disturbances (industrial effluent, aquacultural wastewater, domestic sewage, confluences, dam and wetlands) were further conducted. The results revealed that water quality parameters had significant spatial heterogeneity in water samples of different disturbed sites, and the different types of disturbances shaped the abundance and distribution of bacterial communities. Among these disturbances, dam altered the hydrological and hydraulic conditions of this river, leading to the worst water quality, with the fermentative microorganism Lactococcus becoming the dominant genus. Natural wetlands surrounding the terminus of this river had recuperative functions and could restore water quality and microbial community. The WQI values 38.08–63.46 were rated as “low” or “moderate” and primarily affected by excessive nutrient contaminates, such as nitrogen, phosphorus, and organic matter. Random forest analysis revealed that the biomarkers for water quality were C39, Trichococcus, norank_f_norank_o_Chloroplast, and unclassified_f_Enterobacteriaceae. This study not only facilitated a more comprehensive understanding about the correlation between water quality and bacterial communities of river ecosystem but also provided theoretical support for ecological restoration and governmental regulation of the water ecosystem.

砷还原微生物在原生高砷地下水形成中起关键作用,研究其对不同环境因素改变的响应以及对砷迁移与转化的影响是十分必要的.从石门土壤中分离得到一株耐酸砷还原菌,研究其形态和生理生化特征,通过分子生物学和微生物学手段对其进行系统分类和生理生化特性鉴定,并使用微生物学方法在不同温度、pH值和电子供体条件下进行培养,探究其对环境因素波动的适应能力,检测菌株对高砷土壤砷释放的影响.实验结果表明:该耐酸砷还原菌为芽孢杆菌属(Bacillus)成员,故命名为Bacillussp.strain P3-23(以下简称P3-23);菌株P3-23最适宜的生长温度为30℃,在pH值为3.5?7.5范围内均可生长且具有砷还原能力,能够利用乳酸钠、丙酮酸钠、柠檬酸钠、酵母味素、丙三醇、葡萄糖、蔗糖为电子供体;菌株P3-23能够在72 h内完全还原2.0 mM As(V)且菌液浓度呈上升趋势,具有强耐砷能力,40.0 mM砷存在条件下仍能生长;菌株P3-23促进土壤中砷释放能力较强,砷形态分析显示释放的可溶性砷中As3+占比达83.3％以上.菌株P3-23的分离不仅丰富了人们对砷还原微生物的认识,也说明砷还原微生物对不同环境因素胁迫具有相应的应答机制,预示着其可能存在于极端环境中.对不同环境中砷还原微生物进行研究,在完善砷的生物地球化学循环模式的同时有助于砷污染机制及砷修复生物手段的探索.

Microbial sulfate reduction, a vital mechanism for microorganisms living in anaerobic, sulfate-rich environments, is an essential aspect of the sulfur biogeochemical cycle. However, there has been no detailed investigation of the diversity and distribution of SRBs and its effect in Shimen Realgar Mine, which is characterized as a hot research area rich in sulfate. To elucidate this issue, soils sample from Shimen Realgar Mine were collected. Further, a total of 55 new or new-type dissimilatory sulfite reductase genes and 5 new families of DrsAB proteins were successfully identified, which demonstrate the rich and unique diversity of the sulfate reducing microbes in this environment. We also isolate a novel DSRP strain, Desulfotomaculum sp. JL90 from the soils, which can efficiently respiratory reduces sulfate and arsenate. JL90 also can promote the generation of yellow precipitations in the presence of multiple electron acceptors (both contain sulfate and As(V) in the cultures). Moreover, microbial community compositions also indicated the biogenesis contribution of SRBs to the Shimen realgar mine. The results of this study provided a new insight into the diversity and distribution of SRBs and its ecological effect in Shimen Realgar Mine.

国标法GB 12297—1990《石灰性土壤有效磷测定方法》明确测定土壤有效磷需恒温振荡浸提30min和无磷滤纸过滤30min,测定时间长,检测效率低.为提高土壤有效磷测试效率,引入超声浸提、离心过滤法对国标法浸提和分离两个主要环节进行优化.选取3种不同的土壤样品进行比测实验,实验结果表明:超声10min、10000rpm转速离心5min所测结果与国标法十分接近,且具有稳定的正相关关系(R2=0.99994).改进方法具有简化步骤、缩短时间、节约成本并可一次性处理多个样本等优点,大大提高了土壤有效磷的测定效率.

[目的]探究江汉平原土著砷还原微生物如何介导臭葱石的溶解和释放过程,以及硝酸盐和硫酸盐对该过程的影响.[方法]采集江汉平原高砷沉积物,利用多轮传代富集方法筛选出一株兼性厌氧砷还原菌;克隆其16S rRNA基因、砷还原酶基因(arsC)、硫代硫酸盐还原酶基因(phsA)、硝酸盐还原酶基因(nar)以获得其分类地位;分析该细菌的As(Ⅴ)、NO3-、Fe(Ⅲ)、S2O32-还原功能;利用microcosm技术分析该菌株催化臭葱石中不可溶砷和铁的溶解和释放作用及硝酸盐和硫酸盐对此过程的影响;采用X-射线衍射(XRD)和扫描电镜(SEM)等方法对细菌作用前后的矿物表面形貌进行分析.[结果]16S rRNA基因测序结果表明该细菌为柠檬酸杆菌属(Citrobacter sp.),故命名为Citrobacter sp.A11;在Citrobacter sp.A11作用下,0.45 mmol/L As(Ⅴ)在4d内被还原成As(Ⅲ),2.0 mmol/L 82O32-在6d内被还原成S2-,1.0 mmol/L Fe(Ⅲ)在3d内被还原成Fe(Ⅱ),140.0 mg/L NO3-在28h内被还原成NO2-;经过28d该细菌的催化作用使得体系中不可溶砷和铁的释放量分别为33.68 μmol/L、51.93 μmol/L;硫酸根的加入使得砷和铁的释放量分别增长了41.04％和34.30％,硝酸根的加入则使砷和铁释放量分别降低了35.07％和53.46％.XRD、SEM-EDS分析表明,细菌作用后的臭葱石表面形貌发生明显改变,并出现细小且分散的溶解性颗粒.[结论]本次研究从江汉平原高砷沉积物中富集分离得到一株兼性厌氧砷还原细菌Citrobacter sp.A11,能有效还原As(Ⅴ)、S2O32-、NO3-、Fe(Ⅲ);砷还原细菌Citrobacter sp.A11能显著促进臭葱石中砷和铁的溶解和释放,硫酸根离子的存在会促进细菌介导臭葱石中固态砷、铁的释放,而硝酸根离子的存在则对此过程起明显抑制作用.

It is well established that arsenopyrite can be dissolved by both oxygen and microbes under oxic conditions; however, little is known about whether it can be mobilized under anoxic conditions. Here, we isolated a dissimilatory arsenate-respiring prokaryote (DARP) strain (Citrobacter sp. A99) from arsenic-contaminated soils. It respires arsenate, ferric iron and thiosulfate, but not sulfate. Molecular features of A99 suggest that it is a new DARP. A99 can promote the dissolution and release of arsenic from arsenopyrite, and addition of sulfate enhanced the microbial dissolution of arsenic. SEM/EDS analysis suggested that the bioreduction led to marked changes in the mineral structure, and the residual grains contained much lower contents of arsenic compared to wild-type minerals. Based on the findings of this work, a mechanic hypothesis was proposed to explain the reductive dissolution of arsenopyrite catalyzed by A99 cells. This work suggests that arsenopyrite can be significantly reduced and dissolved by indigenous DARPs under anaerobic conditions.

It was well established that microbial communities are the major drive for the formation of arsenic-contaminated groundwater. However, it remains to be elucidated for how nitrate/nitrite affects the microorganisms-catalyzed dissolution and reduction of arsenic. To address this issue, we collected soil samples containing high-contents of arsenic from the Shimen Realgar Mine area. Microcosm assay indicated that addition of nitrate/nitrite significantly inhibited the dissolution, reduction and release of As and Fe caused by the biological catalysis of microbial communities in the soils, meanwhile nitrate/nitrite was reduced into N-2. To further investigate the molecular mechanism of this finding, we used a representative dissimilatory arsenate-respiring strain Shewanella sp. GL90 from the soils to perform the arsenic release assay. GL90 can efficiently catalyze the reductive dissolution, and promote the release of As and Fe in soils. It is interesting to see that the addition of nitrate/nitrite to the soils led to marked decreases in the GL90-mediated dissolution of As and Fe in the soils. Moreover, we found that this finding was attributed to that nitrate/nitrite significantly inhibited the transcription of the gene of the respiratory arsenate reductase protein in GL90 cells. This work provided new insights into the mechanisms for the coupling of As, N and Fe geochemical cycles in arsenic-rich soils, and for how environmental factors affect As concentration in groundwater.

为探知耐砷微生物对高砷沉积物中砷释放的影响,从石门高砷沉积物中分离得到菌株Pseudomonas 2-23T,根据其生理生化特征和16S rRNA序列同源性对其进行鉴定,并考察该菌株在不同碳源、温度和砷浓度条件下的生长状况,探究该菌株在有氧及厌氧条件下对高砷沉积物中砷释放的影响.结果 表明:菌株2 23T是一株耐砷菌,属于γ-变形菌门中的假单胞菌,命名为Pseudomonas 2-23T;它的最适生长温度为30℃,在含1.0 mM砷的条件下比较利于细菌的生长;其能够利用乳酸钠、草酸钠、柠檬酸钠、丙酮酸钠和乙酸钠作为碳源,而不能利用碳酸氢钠、甲酸钠、葡萄糖和蔗糖作为碳源;菌株Pseudomonas 2-23T在厌氧条件下促进高砷沉积物中砷释放的能力明显强于有氧条件.

The soils near the abandoned Shimen Realgar Mine are characterized by containing extremely high contents of total and soluble arsenic. To determine the microbial reactions and environmental factors affecting the mobilization and release of arsenic from soils phase into pore water, we collected 24 soil samples from the representative points around the abandoned Shimen Realgar Mine. They contained 8310.84 mg/kg total arsenic and 703.21 mg/kg soluble arsenic in average. The soluble arsenic in the soils shows significant positive and negative correlations with environmental SO42-/TOC/pH/PO43-, and Fe/Mn, respectively. We found that diverse dissimilatory As(V)-respiring prokaryotes (DARPs) and As(III)-oxidizing bacteria (AOB) exist in all the examined soil samples. The activities of DARPs led to 65-1275% increase of soluble As(III) in the examined soils after 21.0 days of anaerobic incubation, and the microbial dissolution and releases of arsenic show significant positive and negative correlations with the environmental pH/TN and NH4+/PO43-, respectively. In comparison, the activities of AOB led to 24-346% inhibition of the dissolved oxygen-mediated dissolution of arsenic in the soils, and the AOB-mediated releases of As(V) show significant positive and negative correlations with the environmental SO42- and pH/NH4+, respectively. The microbial communities of 24 samples contain 54 phyla of bacteria that show extremely high diversities. Total arsenic, TOC, NO3- and pH are the key environmental factors that indirectly controlled the mobilization and release of arsenic via influencing the structures of the microbial communities in the soils. This work gained new insights into the mechanism for how microbial communities catalyze the dissolution and releases of arsenic from the soils with extremely high contents of arsenic.