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Microbially Induced Carbonate Precipitation (MICP) is currently viewed as one of the potential prominent processes for field applications towards the prevention of soil erosion, healing cracks in bricks, and groundwater contamination. Typically, the bacteria involved in MICP manipulate their environment leading to calcite precipitation with an enzyme such as urease, causing calcite crystals to form on the surface of grains forming cementation bonds between particles that help in reducing soil permeability and increase overall compressive strength. In this paper, the main focus is to study the MICP performance of three indigenous landfill bacteria against a well-known commercially bought MICP bacteria (Bacillus megaterium) using sand columns. In order to check the viability of the method for potential field conditions, the tests were carried out at slightly less favourable environmental conditions, i.e., at temperatures between 15-17°C and without the addition of urease enzymes. Furthermore, the sand was loose without any compaction to imitate real ground conditions. The results showed that the indigenous bacteria yielded similar permeability reduction (4.79 E-05 to 5.65 E-05) and calcium carbonate formation (14.4–14.7%) to the control bacteria (Bacillus megaterium), which had permeability reduction of 4.56 E-5 and CaCO3 of 13.6%. Also, reasonably good unconfined compressive strengths (160–258 kPa) were noted for the indigenous bacteria samples (160 kPa). SEM and XRD showed the variation of biocrystals formation mainly detected as Calcite and Vaterite. Overall, all of the indigenous bacteria performed slightly better than the control bacteria in strength, permeability, and CaCO3 precipitation. In retrospect, this study provides clear evidence that the indigenous bacteria in such environments can provide similar calcite precipitation potential as well-documented bacteria from cell culture banks. Hence, the idea of MICP field application through biostimulation of indigenous bacteria rather than bioaugmentation can become a reality in the near future.
Adharsh Rajasekar; Charles K. S. Moy; Stephen Wilkinson; Raju Sekar. Microbially induced calcite precipitation performance of multiple landfill indigenous bacteria compared to a commercially available bacteria in porous media. PLoS ONE 2021, 16, e0254676 .
AMA StyleAdharsh Rajasekar, Charles K. S. Moy, Stephen Wilkinson, Raju Sekar. Microbially induced calcite precipitation performance of multiple landfill indigenous bacteria compared to a commercially available bacteria in porous media. PLoS ONE. 2021; 16 (7):e0254676.
Chicago/Turabian StyleAdharsh Rajasekar; Charles K. S. Moy; Stephen Wilkinson; Raju Sekar. 2021. "Microbially induced calcite precipitation performance of multiple landfill indigenous bacteria compared to a commercially available bacteria in porous media." PLoS ONE 16, no. 7: e0254676.
Freshwaters in China are affected by point and non-point sources of pollution. The Wujiang District (Suzhou City, China) has a long history of canals, rivers, and lakes that are currently facing various water quality issues. In this study, the water quality of four rivers and a lake in Wujiang was assessed to quantify pollution and explore its causes. Seventy-five monthly samples were collected from these water bodies (five locations/samples per area) from August to October 2020 and were compared with nine control samples collected from a water protection area. Fifteen physicochemical, microbiological, and molecular–microbiological parameters were analyzed, including nutrients, total and fecal coliforms, and fecal markers. Significant monthly variation was observed for most parameters at all areas. Total phosphorus, phosphates, total nitrogen, ammonium–nitrogen, and fecal coliforms mostly exceeded the acceptable limits set by the Chinese Ministry of Environmental Protection. The LiPuDang Lake and the WuFangGang River were the most degraded areas. The studied parameters were correlated with urban, agricultural, industrial, and other major land use patterns. The results suggest that fecal contamination and nutrients, associated with certain land use practices, are the primary pollution factors in the Wujiang District. Detailed water quality monitoring and targeted management strategies are necessary to control pollution in Wujiang’s watersheds.
Raju Sekar; Xin Jin; Shuang Liu; Jing Lu; Jianwei Shen; Yingya Zhou; Ziyang Gong; Xueying Feng; Shengjie Guo; Wenlong Li. Fecal Contamination and High Nutrient Levels Pollute the Watersheds of Wujiang, China. Water 2021, 13, 457 .
AMA StyleRaju Sekar, Xin Jin, Shuang Liu, Jing Lu, Jianwei Shen, Yingya Zhou, Ziyang Gong, Xueying Feng, Shengjie Guo, Wenlong Li. Fecal Contamination and High Nutrient Levels Pollute the Watersheds of Wujiang, China. Water. 2021; 13 (4):457.
Chicago/Turabian StyleRaju Sekar; Xin Jin; Shuang Liu; Jing Lu; Jianwei Shen; Yingya Zhou; Ziyang Gong; Xueying Feng; Shengjie Guo; Wenlong Li. 2021. "Fecal Contamination and High Nutrient Levels Pollute the Watersheds of Wujiang, China." Water 13, no. 4: 457.
The sharp redox gradient at soil-water interfaces (SWI) plays a key role in controlling arsenic (As) translocation and transformation in paddy soils. When Eh drops, As is released to porewater from solid iron (Fe) and manganese (Mn) minerals and reduced to arsenite. However, the coupling or decoupling processes operating within the redox gradient at the SWI in flooded paddy soils remain poorly constrained due to the lack of direct evidence. In this paper, we reported the mm-scale mapping of Fe, As and other associated elements across the redox gradient in the SWI of five different paddy soils. The results showed a strong positive linear relationship between dissolved Fe, Mn, As, and phosphorus (P) in 4 out of the 5 paddy soils, indicating the general coupling of these elements. However, decoupling of Fe, Mn and As was observed in one of the paddy soils. In this soil, distinct releasing profiles of Mn, As and Fe were observed, and the releasing order followed the redox ladder. Further investigation of As species showed the ratio of arsenite to total As dropped from 100% to 75.5% and then kept stable along depth of the soil profile, which indicates a dynamic equilibrium between arsenite oxidization and arsenate reduction. This study provides direct evidence of multi-elements’ interaction along redox gradient of SWI in paddy soils.
Zhao-Feng Yuan; Williamson Gustave; John Boyle; Raju Sekar; Jonathan Bridge; Yuxiang Ren; Xianjin Tang; Bin Guo; Zheng Chen. Arsenic behavior across soil-water interfaces in paddy soils: Coupling, decoupling and speciation. Chemosphere 2020, 269, 128713 .
AMA StyleZhao-Feng Yuan, Williamson Gustave, John Boyle, Raju Sekar, Jonathan Bridge, Yuxiang Ren, Xianjin Tang, Bin Guo, Zheng Chen. Arsenic behavior across soil-water interfaces in paddy soils: Coupling, decoupling and speciation. Chemosphere. 2020; 269 ():128713.
Chicago/Turabian StyleZhao-Feng Yuan; Williamson Gustave; John Boyle; Raju Sekar; Jonathan Bridge; Yuxiang Ren; Xianjin Tang; Bin Guo; Zheng Chen. 2020. "Arsenic behavior across soil-water interfaces in paddy soils: Coupling, decoupling and speciation." Chemosphere 269, no. : 128713.
Microbial communities are fundamental components in freshwater, and community shifts in ecosystem structure are indicative of changing environmental conditions. This study aimed at investigating the influence of key environmental parameters on bacterial diversity and ecosystem functioning (i.e. organic matter breakdown) in laboratory freshwater microcosms. The effects of varying temperatures (5, 20 and 35 °C), nutrients (representing low, medium and high urbanization) and heavy metals Copper (Cu) and Zinc (Zn) on bacterial diversity and organic matter (OM) breakdown were studied by using leaf bags and capsules filled with polycaprolactonediol-2000 (PCP-2000), respectively. The leaf-associated bacterial diversity was determined by next-generation sequencing of SSU rRNA gene amplicons. The results showed that bacterial diversity increased at high temperature (35 °C) with more operational taxonomic units (OTUs) as compared to medium (20 °C) or low (5 °C) temperatures, whereas nutrient variation had fewer effects on the bacterial community structure. In contrast, the presence of heavy metals, especially high concentrations (100 μM) of Cu, reduced the number of OTUs in the leaf-associated bacterial community. The higher temperatures and nutrient levels accelerated PCP-2000 breakdown rate, but this was impeded by a high concentration (100 μM) of Cu in the short term, though no effect of Zn on breakdown rate was observed. The overall results indicate that temperature and variated heavy metals are among the key factors that affect bacterial diversity and ecosystem functioning in freshwater systems.
Tianma Yuan; Alan J. McCarthy; Yixin Zhang; Raju Sekar. Impact of Temperature, Nutrients and Heavy Metals on Bacterial Diversity and Ecosystem Functioning Studied by Freshwater Microcosms and High-Throughput DNA Sequencing. Current Microbiology 2020, 77, 3512 -3525.
AMA StyleTianma Yuan, Alan J. McCarthy, Yixin Zhang, Raju Sekar. Impact of Temperature, Nutrients and Heavy Metals on Bacterial Diversity and Ecosystem Functioning Studied by Freshwater Microcosms and High-Throughput DNA Sequencing. Current Microbiology. 2020; 77 (11):3512-3525.
Chicago/Turabian StyleTianma Yuan; Alan J. McCarthy; Yixin Zhang; Raju Sekar. 2020. "Impact of Temperature, Nutrients and Heavy Metals on Bacterial Diversity and Ecosystem Functioning Studied by Freshwater Microcosms and High-Throughput DNA Sequencing." Current Microbiology 77, no. 11: 3512-3525.
Fungi are an important, yet often, neglected component of the aquatic microflora, and is responsible for primary decomposition and further processing of organic matter. By comparison, the ecological roles of terrestrial fungi have been well-studied, but the diversity and function of fungi that populate aquatic environments remain poorly understood. Here, the impact of urbanization on fungal diversity and community composition in the canal system of Suzhou was assessed by sequencing the internal transcribed spacer 1 (ITS1) region of the rRNA operon. It was amplified from environmental DNA that has been extracted from water samples and pre-deployed decomposing leaves collected from nine sampling locations (high, medium and low urbanization) over two seasons. The fungal diversity and community composition were determined by bioinformatic analysis of the large DNA sequence datasets generated to identify operational taxonomic units (OTUs) for phylogenetic assignment; over 1 million amplicons were sequenced from 36 samples. The alpha-diversity estimates showed high differences in fungal diversity between water and leaf samples, and winter versus summer. Higher numbers of fungal OTUs were identified in both water and leaf samples collected in the summer, and fungal diversity was also generally higher in water than on colonized leaves in both seasons. The fungal community on leaves was usually dominated by Ascomycetes, especially in winter, while water samples contained more diversity at phylum level with Chytridiomycetes often prominent, particularly in summer. At a genus level, a very high relative abundance of Alternaria on leaves was observed in winter at all locations, in contrast to very low abundance of this genus across all water samples. Fungal community composition also varied between sampling locations (i.e., urbanization); in cluster analysis, samples from high urbanization locations formed a distinct cluster, with medium and low urbanization samples clustering together or in some instances, separately. Redundancy analysis shed further light on the relationships between variation in fungal community composition and water physico-chemical properties. Fungal community diversity variation and correlation with different parameters is discussed in detail, but overall, the influence of season outweighed that of urbanization. This study is significant in cataloguing the impact of urbanization on fungal diversity to inform future restoration of urban canal systems on the importance of protecting the natural aquatic fungal flora.
Tianma Yuan; Haihan Zhang; Qiaoli Feng; Xiangyu Wu; Yixin Zhang; Alan McCarthy; Raju Sekar. Changes in Fungal Community Structure in Freshwater Canals across a Gradient of Urbanization. Water 2020, 12, 1917 .
AMA StyleTianma Yuan, Haihan Zhang, Qiaoli Feng, Xiangyu Wu, Yixin Zhang, Alan McCarthy, Raju Sekar. Changes in Fungal Community Structure in Freshwater Canals across a Gradient of Urbanization. Water. 2020; 12 (7):1917.
Chicago/Turabian StyleTianma Yuan; Haihan Zhang; Qiaoli Feng; Xiangyu Wu; Yixin Zhang; Alan McCarthy; Raju Sekar. 2020. "Changes in Fungal Community Structure in Freshwater Canals across a Gradient of Urbanization." Water 12, no. 7: 1917.
Ecological restoration of freshwater ecosystems is now being implemented to mitigate anthropogenic disruption. Most emphasis is placed on assessing physico-chemical and hydromorphological properties to monitor restoration progress. However, less is known about the structural integrity and ecosystem health of aquatic ecosystems. In particular, little is known about how ecosystem function changes following river habitat restoration, especially in China. Leaf litter decomposition can be used as an indicator of stream ecosystem integrity. Therefore, the leaf breakdown rate was measured to assess the ecosystem function of restored rivers. By comparing leaf breakdown rates in urban rivers undergoing habitat restoration with that in degraded urban rivers and rivers in forested areas (i.e., reference conditions), we aimed to determine: (i) how habitat restoration affected leaf litter decomposition? (ii) the relationship between leaf litter decomposition to both environmental (habitat and physico-chemical variables) and biological factors (benthic communities), and (iii) identify the factors that contribute most to the variance in leaf litter breakdown rates. The results demonstrated a significant increase in leaf breakdown rate (120% in summer and 28% in winter) in the restored rivers compared to the degraded rivers. All environmental and biotic factors evaluated contributed synergistically to the differences in leaf litter decomposition among the three river types. The role of macroinvertebrates, mainly shredders, appeared to be particularly important, contributing 52% (summer) and 33% (winter) to the variance in decomposition, followed by habitat characteristics (e.g. substrate diversity, water velocity; 17% in summer, 29% in winter), physico-chemical variables (e.g. nutrient and organic pollutants; 11% in summer, 1% in winter) and biofilm bacteria (0% in summer, 15% in winter). Habitat restoration positively affected the structure and function of the previously degraded streams. Knowledge on controlling variables and their attribution to changes of ecosystem functioning provides guidance to assist the future planning of ecological restoration strategies.
Qiaoyan Lin; Yixin Zhang; Rob Marrs; Raju Sekar; Xin Luo; Naicheng Wu. Evaluating ecosystem functioning following river restoration: the role of hydromorphology, bacteria, and macroinvertebrates. Science of The Total Environment 2020, 743, 140583 .
AMA StyleQiaoyan Lin, Yixin Zhang, Rob Marrs, Raju Sekar, Xin Luo, Naicheng Wu. Evaluating ecosystem functioning following river restoration: the role of hydromorphology, bacteria, and macroinvertebrates. Science of The Total Environment. 2020; 743 ():140583.
Chicago/Turabian StyleQiaoyan Lin; Yixin Zhang; Rob Marrs; Raju Sekar; Xin Luo; Naicheng Wu. 2020. "Evaluating ecosystem functioning following river restoration: the role of hydromorphology, bacteria, and macroinvertebrates." Science of The Total Environment 743, no. : 140583.
In aquatic ecosystems, water microbial communities can trigger the outbreak or decline of cyanobacterial blooms. However, the microbiological drivers of Microcystis decomposition in reservoirs remain unclear. Here, we explored the bacterial community metabolic profile and co-occurrence dynamics during Microcystis decomposition. The results showed that the decomposition of Microcystis greatly altered the metabolic characteristics and composition of the water bacterial community. Significant variations in bacterial community composition were observed: the bacterial community was mainly dominated by Proteobacteria, Actinobacteria, Planctomycetes, and Bacteroidetes during Microcystis decomposition. Additionally, members of Exiguobacterium, Rhodobacter, and Stenotrophomonas significantly increased during the terminal stages. Dissolved organic matters (DOM) primarily composed of fulvic-like, humic acid-like, and tryptophan-like components, which varied distinctly during Microcystis decomposition. Additionally, the metabolic activity of the bacterial community showed a continuous decrease during Microcystis decomposition. Functional prediction showed a sharp increase in the cell communication and sensory systems of the bacterial communities from day 12 to day 22. Co-occurrence networks showed that bacteria responded significantly to variations in the dynamics of Microcystis decomposition through close interactions between each other. Redundancy analysis (RDA) indicated that Chlorophyll a, nitrate nitrogen (NO3−-N), dissolved oxygen (DO), and dissolved organic carbon (DOC) were crucial drivers for shaping the bacterial community structure. Taken together, these findings highlight the dynamics of the water bacterial community during Microcystis decomposition from the perspective of metabolism and community composition, however, further studies are needed to understand the algal degradation process associated with bacteria.
Shengnan Chen; Miaomiao Yan; Tinglin Huang; Hui Zhang; Kaiwen Liu; Xin Huang; Nan Li; Yutian Miao; Raju Sekar. Disentangling the drivers of Microcystis decomposition: Metabolic profile and co-occurrence of bacterial community. Science of The Total Environment 2020, 739, 140062 .
AMA StyleShengnan Chen, Miaomiao Yan, Tinglin Huang, Hui Zhang, Kaiwen Liu, Xin Huang, Nan Li, Yutian Miao, Raju Sekar. Disentangling the drivers of Microcystis decomposition: Metabolic profile and co-occurrence of bacterial community. Science of The Total Environment. 2020; 739 ():140062.
Chicago/Turabian StyleShengnan Chen; Miaomiao Yan; Tinglin Huang; Hui Zhang; Kaiwen Liu; Xin Huang; Nan Li; Yutian Miao; Raju Sekar. 2020. "Disentangling the drivers of Microcystis decomposition: Metabolic profile and co-occurrence of bacterial community." Science of The Total Environment 739, no. : 140062.
Taihu Lake is one of the largest freshwater lakes in China and serves as an important source for drinking water. This lake is suffering from eutrophication, cyanobacterial blooms and fecal pollution, and the inflow Tiaoxi River is one of the main contributors. The goal here was to characterize the bacterial community structure of Tiaoxi River water by next-generation sequencing (NGS), paying attention to bacteria that are either fecal-associated or pathogenic, and to examine the relationship between environmental parameters and bacterial community structure. Water samples collected from 15 locations in three seasons, and fecal samples collected from different hosts and wastewater samples were used for bacterial community analysis. The phyla Proteobacteria, Actinobacteria, Bacteroidetes, and Cyanobacteria were predominant in most of the water samples tested. In fecal samples, Bacteroidetes, Firmicutes, and Proteobacteria were abundant, while wastewater samples were dominated by Proteobacteria, Bacteroidetes, Acidobacteria, and Chloroflexi. The cluster analysis and principal coordinate analysis indicated that bacterial community structure was significantly different between water, fecal and sewage samples. Shared OTUs between water samples and chicken, pig, and human fecal samples ranged from 4.5 to 9.8% indicating the presence of avian, pig and human fecal contamination in Tiaoxi River. At genus level, five bacterial genera of fecal origin and sequences of seven potential pathogens were detected in many locations and their presence was correlated well with the land use pattern. The sequencing data revealed that Faecalibacterium could be a potential target for human-associated microbial source-tracking qPCR assays. Our results suggest that pH, conductivity, and temperature were the main environmental factors in shaping the bacterial community based on redundancy analysis. Overall, NGS is a valuable tool for preliminary investigation of environmental samples to identify the potential human health risk, providing specific information about fecal and potentially pathogenic bacteria that can be followed up by specific methods.
Kiran Kumar Vadde; Qiaoli Feng; Jianjun Wang; Alan J. McCarthy; Raju Sekar. Next-generation sequencing reveals fecal contamination and potentially pathogenic bacteria in a major inflow river of Taihu Lake. Environmental Pollution 2019, 254, 113108 .
AMA StyleKiran Kumar Vadde, Qiaoli Feng, Jianjun Wang, Alan J. McCarthy, Raju Sekar. Next-generation sequencing reveals fecal contamination and potentially pathogenic bacteria in a major inflow river of Taihu Lake. Environmental Pollution. 2019; 254 ():113108.
Chicago/Turabian StyleKiran Kumar Vadde; Qiaoli Feng; Jianjun Wang; Alan J. McCarthy; Raju Sekar. 2019. "Next-generation sequencing reveals fecal contamination and potentially pathogenic bacteria in a major inflow river of Taihu Lake." Environmental Pollution 254, no. : 113108.
Arsenic (As) mobility in paddy soils is mainly controlled by iron (Fe) oxides and iron reducing bacteria (IBR). The Fe reducing bacteria are also considered to be enriched on the anode of soil microbial fuel cells (sMFC). Thus, the sMFC may have an impact on elements’ behavior, especially Fe and As, mobilization and immobilization in paddy soils. In this study, we found dissolved organic matter (DOC) abundance was a major determinate for the sMFC impact on Fe and As. In the constructed sMFCs with and without water management, distinctive behaviors of Fe and As in paddy soil were observed, which can be explained by the low or high DOC content under different water management. When the sMFC was deployed without water management, i.e. DOC was abundant, the sMFC promoted Fe and As movement into the soil porewater. The As release into the porewater was associated with the enhanced Fe reduction by the sMFC. This was ascribed to the acidification effect of sMFC anode and the increase of Fe reducing bacteria in the sMFC anode vicinity and associated bulk soil. However, when the sMFC was coupled with alternating dry-wet cycles, i.e. DOC was limited, the Fe and As concentrations in the soil porewater dramatically decreased by up to 2.3 and 1.6 fold, respectively, compared to the controls under the same water management regime. This study implies an environmental risk for the in-situ application of sMFC in organic matter rich wetlands and also points out a new mitigation strategy for As management in paddy soils.
Williamson Gustave; Zhao-Feng Yuan; Raju Sekar; Yu-Xiang Ren; Jinjing-Yuan Liu; Jun Zhang; Zheng Chen. Soil organic matter amount determines the behavior of iron and arsenic in paddy soil with microbial fuel cells. Chemosphere 2019, 237, 124459 .
AMA StyleWilliamson Gustave, Zhao-Feng Yuan, Raju Sekar, Yu-Xiang Ren, Jinjing-Yuan Liu, Jun Zhang, Zheng Chen. Soil organic matter amount determines the behavior of iron and arsenic in paddy soil with microbial fuel cells. Chemosphere. 2019; 237 ():124459.
Chicago/Turabian StyleWilliamson Gustave; Zhao-Feng Yuan; Raju Sekar; Yu-Xiang Ren; Jinjing-Yuan Liu; Jun Zhang; Zheng Chen. 2019. "Soil organic matter amount determines the behavior of iron and arsenic in paddy soil with microbial fuel cells." Chemosphere 237, no. : 124459.
Across the world, there have been increasing attempts to restore good ecological condition to degraded rivers through habitat restoration. Microbial communities developing as biofilms play an important role in river ecosystem functioning by driving organic matter decomposition and ecosystem respiration. However, little is known about the structure and function of microbial communities in riverine systems and how these change when habitat restoration is implemented. Here, we compared the biofilm bacterial community composition using 16S rRNA genes targeted high-throughput Illumina Miseq sequencing in three river types, degraded urban rivers, urban rivers undergoing habitat restoration and forested rivers (our reference conditions). We aimed to determine: (i) the biofilm bacterial community composition affected by habitat restoration (ii) the difference in bacterial diversity in restored rivers, and (iii) correlations between environmental variables and bacterial community composition. The results showed that both water quality and biofilm bacterial community structure were changed by habitat restoration. In rivers where habitat had been restored, there was an increase in dissolved oxygen, a reduction in organic pollutants, a reduction in bacterial diversity and a related developing pattern of microbial communities, which is moving towards that of the reference conditions (forested rivers). River habitat management stimulated the processing of organic pollutants through the variation in microbial community composition, however, a big difference in bacterial structure still existed between the restored rivers and the reference forest rivers. Thus, habitat restoration is an efficient way of modifying the biofilm microbial community composition for sustainable freshwater management. It will, however, take a much longer time for degraded rivers to attain a similar ecosystem quality as the “pristine” forest sites than the seven years of restoration studied here.
Qiaoyan Lin; Raju Sekar; Rob Marrs; Yixin Zhang. Effect of River Ecological Restoration on Biofilm Microbial Community Composition. Water 2019, 11, 1244 .
AMA StyleQiaoyan Lin, Raju Sekar, Rob Marrs, Yixin Zhang. Effect of River Ecological Restoration on Biofilm Microbial Community Composition. Water. 2019; 11 (6):1244.
Chicago/Turabian StyleQiaoyan Lin; Raju Sekar; Rob Marrs; Yixin Zhang. 2019. "Effect of River Ecological Restoration on Biofilm Microbial Community Composition." Water 11, no. 6: 1244.
Urbanization is increasing worldwide and is happening at a rapid rate in China in line with economic development. Urbanization can lead to major changes in freshwater environments through multiple chemical and microbial contaminants. We assessed the impact of urbanization on physicochemical characteristics and microbial loading in canals in Suzhou, a city that has experienced rapid urbanization in recent decades. Nine sampling locations covering three urban intensity classes (high, medium and low) in Suzhou were selected for field studies and three locations in Huangshan (natural reserve) were included as pristine control locations. Water samples were collected for physicochemical, microbiological and molecular analyses. Compared to medium and low urbanization sites, there were statistically significant higher levels of nutrients and total and thermotolerant coliforms (or fecal coliforms) in highly urbanized locations. The effect of urbanization was also apparent in the abundances of human-associated fecal markers and bacterial pathogens in water samples from highly urbanized locations. These results correlated well with land use types and anthropogenic activities at the sampling sites. The overall results indicate that urbanization negatively impacts water quality, providing high levels of nutrients and a microbial load that includes fecal markers and pathogens.
Tianma Yuan; Kiran Kumar Vadde; Jonathan D. Tonkin; Jianjun Wang; Jing Lu; Zimeng Zhang; Yixin Zhang; Alan J. McCarthy; Raju Sekar. Urbanization Impacts the Physicochemical Characteristics and Abundance of Fecal Markers and Bacterial Pathogens in Surface Water. International Journal of Environmental Research and Public Health 2019, 16, 1739 .
AMA StyleTianma Yuan, Kiran Kumar Vadde, Jonathan D. Tonkin, Jianjun Wang, Jing Lu, Zimeng Zhang, Yixin Zhang, Alan J. McCarthy, Raju Sekar. Urbanization Impacts the Physicochemical Characteristics and Abundance of Fecal Markers and Bacterial Pathogens in Surface Water. International Journal of Environmental Research and Public Health. 2019; 16 (10):1739.
Chicago/Turabian StyleTianma Yuan; Kiran Kumar Vadde; Jonathan D. Tonkin; Jianjun Wang; Jing Lu; Zimeng Zhang; Yixin Zhang; Alan J. McCarthy; Raju Sekar. 2019. "Urbanization Impacts the Physicochemical Characteristics and Abundance of Fecal Markers and Bacterial Pathogens in Surface Water." International Journal of Environmental Research and Public Health 16, no. 10: 1739.
Taihu Lake is one of the largest freshwater lakes in China, serving as an important source of drinking water; >60% of source water to this lake is provided by the Tiaoxi River. This river faces serious fecal contamination issues, and therefore, a comprehensive investigation to identify the sources of fecal contamination was carried out and is presented here. The performance of existing universal (BacUni and GenBac), human (HF183-Taqman, HF183-SYBR, BacHum, and Hum2), swine (Pig-2-Bac), ruminant (BacCow), and avian (AV4143 and GFD) associated microbial source tracking (MST) markers was evaluated prior to their application in this region. The specificity and sensitivity results indicated that BacUni, HF183-TaqMan, Pig-2-Bac, and GFD assays are the most suitable in identifying human and animal fecal contamination. Therefore, these markers along with marker genes specific to selected bacterial pathogens were quantified in water and sediment samples of the Tiaoxi River, collected from 15 locations over three seasons during 2014 and 2015. Total/universal Bacteroidales markers were detected in all water and sediment samples (mean concentration 6.22 log10 gene copies/100 ml and 6.11 log10 gene copies/gram, respectively), however, the detection of host-associated MST markers varied. Human and avian markers were the most frequently detected in water samples (97 and 89%, respectively), whereas in sediment samples, only human-associated markers were detected more often (86%) than swine (64%) and avian (8.8%) markers. The results indicate that several locations in the Tiaoxi River are heavily polluted by fecal contamination and this correlated well with land use patterns. Among the five bacterial pathogens tested, Shigella spp. and Campylobacter jejuni were the most frequently detected pathogens in water (60% and 62%, respectively) and sediment samples (91% and 53%, respectively). Shiga toxin-producing Escherichia coli (STEC) and pathogenic Leptospira spp. were less frequently detected in water samples (55% and 33%, respectively) and sediment samples (51% and 13%, respectively), whereas E. coli O157:H7 was only detected in sediment samples (11%). Overall, the higher prevalence and concentrations of Campylobacter jejuni, Shigella spp., and STEC, along with the MST marker detection at a number of locations in the Tiaoxi River, indicates poor water quality and a significant human health risk associated with this watercourse.
Kiran Kumar Vadde; Alan J. McCarthy; Rong Rong; Raju Sekar. Quantification of Microbial Source Tracking and Pathogenic Bacterial Markers in Water and Sediments of Tiaoxi River (Taihu Watershed). Frontiers in Microbiology 2019, 10, 699 .
AMA StyleKiran Kumar Vadde, Alan J. McCarthy, Rong Rong, Raju Sekar. Quantification of Microbial Source Tracking and Pathogenic Bacterial Markers in Water and Sediments of Tiaoxi River (Taihu Watershed). Frontiers in Microbiology. 2019; 10 ():699.
Chicago/Turabian StyleKiran Kumar Vadde; Alan J. McCarthy; Rong Rong; Raju Sekar. 2019. "Quantification of Microbial Source Tracking and Pathogenic Bacterial Markers in Water and Sediments of Tiaoxi River (Taihu Watershed)." Frontiers in Microbiology 10, no. : 699.
Soil Microbial Fuel Cells (MFCs) are devices that can generate electricity by using the flooded soil’s anode respiring microbial consortium. When the MFC starts to work, the microbial community in the anode vicinity rapidly changes. This shift in the microbial community results in many dead cells that may release their DNA (relic DNA) and obscure culture independent estimates of microbial community composition. Although relic DNA is expected to increase in MFCs, the effect of relic DNA has not been investigated in the soil MFCs system. In this study the effect of the MFCs on the soil microbial community composition within the soil profile and the influence of relic DNA were investigated. Microbial community analysis revealed that the MFCs deployment significantly influenced the community composition within the soil profile. The phylum Proteobacteria (34.4% vs 23.6%) and the class Deltaproteobacteria (16.8% vs 5.9%) significantly increased in the MFCs compared to the control, while the phylum Firmicutes (24.0% vs 28.7%) and the class Sphingobacteria (5.3% vs 7.0%) were more abundant in the control. Furthermore, the archaeal phyla Euryarchaeota (40.7% vs 52.3%) and Bathyarchaeota (10.1% vs 17.3%) were significantly lower in the MFCs, whereas the phylum Woesearchaeota (DHVEG6) (24.4% vs 19.4%) was slightly enhanced. Moreover, the results showed that relic DNA can affect the relative abundance of Geobacter and Candidatus Methanoperedens, however, it has no significant effects on the microbial community structure. These results indicate that MFCs can influence the soil microbial community profile, nevertheless the relic DNA generated has minimum effect on the culture independent estimates of microbial community composition.
Williamson Gustave; Zhao-Feng Yuan; Raju Sekar; Veronica Toppin; Jinjing-Yuan Liu; Yu-Xiang Ren; Jun Zhang; Zheng Chen. Relic DNA does not obscure the microbial community of paddy soil microbial fuel cells. Research in Microbiology 2018, 170, 97 -104.
AMA StyleWilliamson Gustave, Zhao-Feng Yuan, Raju Sekar, Veronica Toppin, Jinjing-Yuan Liu, Yu-Xiang Ren, Jun Zhang, Zheng Chen. Relic DNA does not obscure the microbial community of paddy soil microbial fuel cells. Research in Microbiology. 2018; 170 (2):97-104.
Chicago/Turabian StyleWilliamson Gustave; Zhao-Feng Yuan; Raju Sekar; Veronica Toppin; Jinjing-Yuan Liu; Yu-Xiang Ren; Jun Zhang; Zheng Chen. 2018. "Relic DNA does not obscure the microbial community of paddy soil microbial fuel cells." Research in Microbiology 170, no. 2: 97-104.
Arsenic (As) behavior in paddy soils couples with the redox process of iron (Fe) minerals. When soil is flooded, Fe oxides are transformed to soluble ferrous ions by accepting the electrons from Fe reducers. This process can significantly affect the fate of As in paddy fields. In this study, we show a novel technique to manipulate the Fe redox processes in paddy soils by deploying soil microbial fuel cells (sMFC). The results showed that the sMFC bioanode can significantly decrease the release of Fe and As into soil porewater. Iron and As contents around sMFC anode were 65.0% and 47.0% of the control respectively at day 50. The observed phenomenon would be explained by a competition for organic substrate between sMFC bioanode and the iron- and arsenic-reducing bacteria in the soils. In the vicinity of bioanode, organic matter removal efficiencies were 10.3% and 14.0% higher than the control for lost on ignition carbon and total organic carbon respectively. Sequencing of the 16S rRNA genes suggested that the influence of bioanodes on bulk soil bacterial community structure was minimal. Moreover, during the experiment a maximum current and power density of 0.31 mA and 12.0 mWm−2 were obtained, respectively. This study shows a novel way to limit the release of Fe and As in soils porewater and simultaneously generate electricity.
Williamson Gustave; Zhao-Feng Yuan; Raju Sekar; Hu-Cheng Chang; Jun Zhang; Mona Wells; Yu-Xiang Ren; Zheng Chen. Arsenic mitigation in paddy soils by using microbial fuel cells. Environmental Pollution 2018, 238, 647 -655.
AMA StyleWilliamson Gustave, Zhao-Feng Yuan, Raju Sekar, Hu-Cheng Chang, Jun Zhang, Mona Wells, Yu-Xiang Ren, Zheng Chen. Arsenic mitigation in paddy soils by using microbial fuel cells. Environmental Pollution. 2018; 238 ():647-655.
Chicago/Turabian StyleWilliamson Gustave; Zhao-Feng Yuan; Raju Sekar; Hu-Cheng Chang; Jun Zhang; Mona Wells; Yu-Xiang Ren; Zheng Chen. 2018. "Arsenic mitigation in paddy soils by using microbial fuel cells." Environmental Pollution 238, no. : 647-655.
Taihu Lake is the third largest freshwater lake in China and serves as a drinking water source for ~30 million residents. Tiaoxi River is one of the main rivers connected to this lake and contributes >60% of the source water. Taihu Lake has been facing various environmental issues; therefore, it is important to study the water quality of its inflow rivers. This study aimed to evaluate the physico-chemical and microbiological characteristics of Tiaoxi River and to determine the spatial and seasonal variations in the water quality. Water samples were collected from 25 locations across the Tiaoxi River in three seasons in 2014–2015. Fourteen water quality parameters including multiple nutrients and indicator bacteria were assessed, and the data analyzed by multivariate statistical analyses. The physico-chemical analysis showed high levels (>1 mg/L) of total nitrogen (TN) in all locations for all seasons. Total phosphorus (TP), nitrite-N (NO2-N), and ammonium-N (NH4-N) exceeded the acceptable limits in some locations and fecal coliform counts were high (>250 CFU/100 mL) in 15 locations. Hierarchical cluster analysis showed that the sampling sites could be grouped into three clusters based on water quality, which were categorized as low, moderate, and high pollution areas. Principal component analysis (PCA) applied to the entire dataset identified four principal components which explained 83% of the variation; pH, conductivity, TP, and NO3-N were found to be the key parameters responsible for variations in water quality. The overall results indicated that some of the sampling locations in the Tiaoxi River are heavily contaminated with pollutants from various sources which can be correlated with land use patterns and anthropogenic activities.
Kiran Kumar Vadde; Jianjun Wang; Long Cao; Tianma Yuan; Alan J. McCarthy; Raju Sekar. Assessment of Water Quality and Identification of Pollution Risk Locations in Tiaoxi River (Taihu Watershed), China. Water 2018, 10, 183 .
AMA StyleKiran Kumar Vadde, Jianjun Wang, Long Cao, Tianma Yuan, Alan J. McCarthy, Raju Sekar. Assessment of Water Quality and Identification of Pollution Risk Locations in Tiaoxi River (Taihu Watershed), China. Water. 2018; 10 (2):183.
Chicago/Turabian StyleKiran Kumar Vadde; Jianjun Wang; Long Cao; Tianma Yuan; Alan J. McCarthy; Raju Sekar. 2018. "Assessment of Water Quality and Identification of Pollution Risk Locations in Tiaoxi River (Taihu Watershed), China." Water 10, no. 2: 183.