The Mycobacterium tuberculosis prolyl dipeptidyl peptidase cleaves the N-terminal peptide of the immunoprotein CXCL-10.

Dipeptidyl peptidases constitute a class of non-classical serine proteases that regulate an array of biological functions, making them pharmacologically attractive enzymes. With this work, we identified and characterized a dipeptidyl peptidase from Mycobacterium tuberculosis (MtDPP) displaying a strong preference for proline residues at the P1 substrate position and an unexpectedly high thermal stability. MtDPP was also characterized with alanine replacements of residues of its active site that yielded, for the most part, loss of catalysis. We show that MtDPP catalytic activity is inhibited by well-known human DPP4 inhibitors. Using MALDI-TOF mass spectrometry we also describe that in vitro, MtDPP mediates the truncation of the C-X-C motif chemokine ligand 10, indicating a plausible role in immune modulation for this mycobacterial enzyme.

Simultaneous measurement of aqueous redox-sensitive elements and their species across the soil-water interface.

The redox-sensitive elements, such as iron, manganese, sulfur, phosphorus, and arsenic, shift their speciation every millimeter (mm) across the soil-water interface in the flooded soil environments. Monitoring of element speciation at this high-resolution (HR) within the SWI is still difficult. The key challenge lies in obtaining sufficient porewater samples at specific locations along the soil gradient for downstream analysis. Here with an optimized inductively coupled plasma mass spectrometry (ICP-MS) method and a HR porewater sampler, we demonstrate mm-scale element profiles mapping across the SWI in paddy soils. High-concentrations of iron and manganese (> 10 mg/L) were measured by ICP-MS in an extended dynamic range mode to avoid signal overflow. The iron profile along the SWI generated by the ICP-MS method showed no significant difference (p < 0.05) compared to that measured independently using a colorimetric method. Furthermore, four arsenic (arsenite, arsenate, monomethylarsonic and dimethylarsinic acid), two phosphorus (phosphite and phosphate) and two sulfur (sulfide and sulfate) species were separated in 10 min by ion chromatography -ICP-MS with the NH4HCO3 mobile phase. We verified the technique using paddy soils collected from the field, and present the mm-scale profiles of iron, manganese, and arsenic, phosphorus, sulfur species (relative standard deviation < 8%). The technique developed in this study will significantly promote the measurement throughput in limited samples (e.g. 100 µL) collected by HR samplers, which would greatly facilitate redox-sensitive elements biogeochemical cycling in saturated soils.

Impact of Temperature, Nutrients and Heavy Metals on Bacterial Diversity and Ecosystem Functioning Studied by Freshwater Microcosms and High-Throughput DNA Sequencing.

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.

Tracing the Dynamic Changes of Element Profiles by Novel Soil Porewater Samplers with Ultralow Disturbance to Soil-Water Interface.

In flooded soils, soil-water interface (SWI) is the key zone controlling biogeochemical dynamics. Chemical species and concentrations vary greatly at micro- to cm-scales. Techniques able to track these changing element profiles both in space and over time with appropriate resolution are rare. Here, we report a patent-pending technique, the Integrated Porewater Injection (IPI) sampler, which is designed for soil porewater sampling with minimum disturbance to saturated soil environment. IPI sampler employs a single hollow fiber membrane tube to passively sample porewater surrounding the tube. When working, it can be integrated into the sample introduction system, thus the sample preparation procedure is dramatically simplified. In this study, IPI samplers were coupled to ICP-MS at data-only mode. The limits of detection of IPI-ICP-MS for Ni, As, Cd, Sb, and Pb were 0.12, 0.67, 0.027, 0.029, and 0.074 µg·L-1, respectively. Furthermore, 25 IPI samplers were assembled into an SWI profiler using 3D printing in a one-dimensional array. The SWI profiler is able to analyze element profiles at high spatial resolution (∼2 mm) every ≥24 h. When deployed in arsenic-contaminated paddy soils, it depicted the distributions and dynamics of multiple elements at anoxic-oxic transition. The results show that the SWI profiler is a powerful and robust technique in monitoring dynamics of element profile in soil porewater at high spatial resolution. The method will greatly facilitate studies of elements behaviors in sediments of wetland, rivers, lakes, and oceans.

Biomineralisation performance of bacteria isolated from a landfill in China.

We report an investigation of microbially induced carbonate precipitation by seven indigenous bacteria isolated from a landfill in China. Bacterial strains were cultured in a medium supplemented with 25 mmol/L calcium chloride and 333 mmol/L urea. The experiments were carried out at 30 °C for 7 days with agitation by a shaking table at 130 r/min. Scanning electron microscopic and X-ray diffraction analyses showed variations in calcium carbonate polymorphs and mineral composition induced by all bacterial strains. The amount of carbonate precipitation was quantified by titration. The amount of carbonate precipitated in the medium varied among isolates, with the lowest being Bacillus aerius rawirorabr15 (LC092833) precipitating around 1.5 times more carbonate per unit volume than the abiotic (blank) solution. Pseudomonas nitroreducens szh_asesj15 (LC090854) was found to be the most efficient, precipitating 3.2 times more carbonate than the abiotic solution. Our results indicate that bacterial carbonate precipitation occurred through ureolysis and suggest that variations in carbonate crystal polymorphs and rates of precipitation were driven by strain-specific differences in urease expression and response to the alkaline environment. These results and the method applied provide benchmarking and screening data for assessing the bioremediation potential of indigenous bacteria for containment of contaminants in landfills.

Next-generation sequencing showing potential leachate influence on bacterial communities around a landfill in China.

The impact of contaminated leachate on groundwater from landfills is well known, but the specific effects on bacterial consortia are less well-studied. Bacterial communities in a landfill and an urban site located in Suzhou, China, were studied using Illumina high-throughput sequencing. A total of 153 944 good-quality reads were produced and sequences assigned to 6388 operational taxonomic units. Bacterial consortia consisted of up to 16 phyla, including Proteobacteria (31.9%-94.9% at landfill, 25.1%-43.3% at urban sites), Actinobacteria (0%-28.7% at landfill, 9.9%-34.3% at urban sites), Bacteroidetes (1.4%-25.6% at landfill, 5.6%-7.8% at urban sites), Chloroflexi (0.4%-26.5% at urban sites only), and unclassified bacteria. Pseudomonas was the dominant (67%-93%) genus in landfill leachate. Arsenic concentrations in landfill raw leachate (RL) (1.11 × 103 µg/L) and fresh leachate (FL2) (1.78 × 103 µg/L) and mercury concentrations in RL (10.9 µg/L) and FL2 (7.37 µg/L) exceeded Chinese State Environmental Protection Administration standards for leachate in landfills. The Shannon diversity index and Chao1 richness estimate showed RL and FL2 lacked richness and diversity when compared with other samples. This is consistent with stresses imposed by elevated arsenic and mercury and has implications for ecological site remediation by bioremediation or natural attenuation.

Abundance and diversity of bacteria in oxygen minimum drinking water reservoir sediments studied by quantitative PCR and pyrosequencing.

Reservoir sediment is one of the most stressful environments for microorganisms due to periodically oxygen minimum conditions. In this study, the abundance and composition of bacteria associated with sediments from three drinking water reservoirs (Zhoucun, ZCR; Shibianyu, SBYR; and Jinpen, JPR) were investigated by quantitative polymerase chain reaction and 16S rRNA-based 454 pyrosequencing. The results of physico-chemical analysis of sediments showed that the organic matter and total nitrogen were significantly higher in ZCR as compared to JPR (P < 0.01). The bacterial abundance was 9.13 × 10(6), 1.14 × 10(7), and 6.35 × 10(6) copies/ng DNA in sediments of SBYR, ZCR, and JPR, respectively (P < 0.01). The pyrosequencing revealed a total of 9,673 operational taxonomic units, which were affiliated with 17 phyla. The dominant phylum was Firmicutes (56.83%) in JPR; whereas, the dominance of Proteobacteria was observed in SBYR with 40.38% and ZCR with 39.56%. The Shannon-Wiener diversity (H') was high in ZCR; whereas, Chao 1 richness was high in SBYR. The dominant genera were Clostridium with 42.15% and Bacillus with 20.44% in JPR. Meanwhile, Dechloromonas with 14.80% and Smithella with 7.20% were dominated in ZCR, and Bacillus with 45.45% and Acinetobacter with 5.15% in SBYR. The heat map profiles and redundancy analysis indicated substantial differences in sediment bacterial community composition among three reservoirs. Moreover, it appears from the results that physico-chemical variables of sediments including pH, organic matter, total nitrogen, and available phosphorous played key roles in shaping the bacterial community diversity. The results obtained from this study will broaden our understanding on the bacterial community structure of sediments in oxygen minimum and stressful freshwater environments.

Mixotrophic aerobic denitrification facilitated by denitrifying bacterial-fungal communities assisted with iron in micro-polluted water: Performance, metabolic activity, functional genes abundance, and community co-occurrence.

Low-dosage nitrate pollutants can contribute to eutrophication in surface water bodies, such as lakes and reservoirs. This study employed assembled denitrifying bacterial-fungal communities as bio-denitrifiers, in combination with zero-valent iron (ZVI), to treat micro-polluted water. Immobilized bacterial-fungal mixed communities (IBFMC) reactors demonstrated their ability to reduce nitrate and organic carbon by over 43.2 % and 53.7 %, respectively. Compared to IBFMC reactors, IBFMC combined with ZVI (IBFMC@ZVI) reactors exhibited enhanced removal efficiencies for nitrate and organic carbon, reaching the highest of 31.55 % and 17.66 %, respectively. The presence of ZVI in the IBFMC@ZVI reactors stimulated various aspects of microbial activity, including the metabolic processes, electron transfer system activities, abundance of functional genes and enzymes, and diversity and richness of microbial communities. The contents of adenosine triphosphate and electron transfer system activities enhanced more than 5.6 and 1.43 folds in the IBFMC@ZVI reactors compared with IBFMC reactors. Furthermore, significant improvement of crucial genes and enzyme denitrification chains was observed in the IBFMC@ZVI reactors. Iron played a central role in enhancing microbial diversity and activity, and promoting the supply, and transfer of inorganic electron donors. This study presents an innovative approach for applying denitrifying bacterial-fungal communities combined with iron enhancing efficient denitrification in micro-polluted water.

Algicidal activity synchronized with nitrogen removal by actinomycetes: Algicidal mechanism, stress response of algal cells, denitrification performance, and indigenous bacterial community co-occurrence.

The harmful algal blooms (HABs) can damage the ecological equilibrium of aquatic ecosystems and threaten human health. The bio-degradation of algal by algicidal bacteria is an environmentally friendly and economical approach to control HABs. This study applied an aerobic denitrification synchronization algicidal strain Streptomyces sp. LJH-12-1 (L1) to control HABs. The cell-free filtrate of the strain L1 showed a great algolytic effect on bloom-forming cyanobacterium, Microcystis aeruginosa (M. aeruginosa). The optimal algicidal property of strain L1 was indirect light-dependent algicidal with an algicidal rate of 85.0%. The functional metabolism, light-trapping, light-transfer efficiency, the content of pigments, and inhibition of photosynthesis of M. aeruginosa decreased after the addition of the supernatant of the strain L1 due to oxidative stress. Moreover, 96.05% nitrate removal rate synchronized with algicidal activity was achieved with the strain L1. The relative abundance of N cycling functional genes significantly increased during the strain L1 effect on M. aeruginosa. The algicidal efficiency of the strain L1 in the raw water was 76.70% with nitrate removal efficiency of 81.4%. Overall, this study provides a novel route to apply bacterial strain with the property of denitrification coupled with algicidal activity in treating micro-polluted water bodies.

A screen-printed, amperometric biosensor for the determination of organophosphorus pesticides in water samples.

An amperometric biosensor based on screen-printed electrodes (SPEs) was developed for the determination of organophosphorus pesticides in water samples. The extent of acetylcholinesterase (AChE) deactivation was determined and quantified for pesticide concentrations in water samples. An enzyme immobilization adsorption procedure and polyacrylamide gel matrix polymerization were used for fabrication of the biosensor, with minimal losses in enzyme activity. The optimal conditions for enzyme catalytic reaction on the SPEs surfaces were acetylthiocholine chloride (ATChCl) concentration of 5 mmol/L, pH 7 and reaction time of 4 min. The detection limits for three organophosphorus pesticides (dichlorvos, monocrotophs and parathion) were in the range of 4 to 7 microg/L when an AChE amount of 0.1 U was used for immobilization.

Diversity and abundance of antibiotic resistance genes and their relationship with nutrients and land use of the inflow rivers of Taihu Lake.

Taihu Lake is the third largest freshwater lake in China and an important source for drinking water, flood protection, aquaculture, agriculture, and other activities. This lake is connected to many principal and small rivers with inflow from west and outflow on the eastern side of the lake and these inflow rivers are believed to significantly contribute to the water pollution of the lake. This study was aimed at assessing the diversity and abundance of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs), and their relationship with water quality parameters and land use patterns. Water samples were collected from 10 major inflow rivers and the source water protection area of the Taihu Lake in spring and summer 2019. High-throughput profiling was used to detect and quantify 384 ARGs and MGEs and in addition, 11 water quality parameters were analyzed. The results showed that the number of ARGs/MGEs detected in each inflow river ranged from 105 to 185 in spring and 107 to 180 in summer. The aminoglycoside resistance genes were the most dominant types ARGs detected followed by beta-lactam resistance, multidrug resistance, macrolide-lincosamide-streptogramin B (MLSB) resistance genes, which contributed to 65% of the ARGs. The water quality parameters showed significant correlation with absolute abundance of ARGs. Furthermore, significant correlation between ARGs and MGEs were also observed which demonstrates potential gene transfer among organisms through horizontal gene transfer via MGEs. ARGs showed strong positive correlation with cultivated and industrial lands whereas, negative correlation was observed with river, lake, forest, land for green buffer, and land for port and harbor. The overall results indicate that the inflow rivers of Taihu Lake are polluted by various sources including multiple nutrients and high abundance of ARGs, which needs attention for better management of the inflow rivers of this lake.

The effect of habitat restoration on macroinvertebrate communities in Shaoxi rivers, China.

In recent decades, the biodiversity of freshwater environments has decreased sharply due to anthropogenic disturbances that damaged ecosystem structures and functions. Habitat restoration has emerged as an important method to mitigate the degradation of river ecosystems. Although in many cases a post-project monitoring has been promoted to access the restoration progress, it is still unclear how aquatic community changes following river habitat restoration in China. Macroinvertebrate communities intermediately positioned within ecosystem food webs play a key role in ecosystem processes within river ecosystem, driving energy flow and nutrient cycling. Here, benthic macroinvertebrates are used as bio-indicators to assess the ecosystem health of degraded urban rivers, restored urban rivers, and undisturbed rivers. This study aims to determine (i) how habitat restoration influences macroinvertebrates diversity and how this compared to degraded and reference conditions; (ii) how did macroinvertebrate community compositions differ in restored, degraded, and reference sites; and (iii) the environmental factors shaping macroinvertebrate communities. Habitat restoration significantly increased the diversity and richness of macroinvertebrate community and intolerant species and shifted the community composition towards reference status. Habitat characteristics and water chemistry, including substrate diversity, water velocity, and both nutrients (TN) and organic pollutants (TOC), appeared to shape the turnover of these communities. Habitat characteristics contributed to most of the variation of the entire macroinvertebrate community. Our research indicates that habitat restoration is an efficient approach to restore the aquatic community and hence improve river ecosystem health for freshwater conservation and sustainable management in Zhejiang province. This study strengthens our understanding of the changes of macroinvertebrate community after habitat restoration and important controlling variables that attribute to these changes, which provides an important guidance for future freshwater management.

Stagnation trigger changes to tap water quality in winter season: Novel insights into bacterial community activity and composition.

The drinking water distribution system is important for water supply and it affects the quality of the drinking water. Indoor pipeline water quality is regulated by physical, hydraulic and biological elements, such as indoor temperature and stagnation. In this work, the effects of indoor heating and overnight stagnation on the variation in bacterial community structure and the total cell count were assessed by full-length 16S rRNA gene sequencing and flow cytometry, respectively. The results exhibited that the average intact cell count was 6.99 × 104 cells/mL and the low nucleic acid (LNA) bacteria was 4.48 × 104 cells/mL after stagnation. The average concentration of total and intracellular adenosine triphosphate (ATP) was 3.64 × 10-12 gATP/mL and 3.13 × 10-17 gATP/cell in stagnant water, respectively. The growth of LNA cells played a crucial role in increasing ATP. The dominant phylum observed was Proteobacteria (87.21 %), followed by Actinobacteria (8.25 %). Opportunistic pathogens increased the risk of disease in stagnant water (up to 1.2-fold for Pseudomonas sp. and 5.8-fold for Mycobacterium sp.). Meanwhile, structural equation model (SEM) and redundancy analysis (RDA) also illustrated that water temperature, residual chlorine and Fe significantly affected the abundance and composition of bacterial community. Taking together, these results show response of tap water quality to overnight stagnation and indoor heating, and provide scientific basis for drinking water security management in winter season.

Microbially induced calcite precipitation performance of multiple landfill indigenous bacteria compared to a commercially available bacteria in porous media.

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.

Combined effects of seasonality and stagnation on tap water quality: Changes in chemical parameters, metabolic activity and co-existence in bacterial community.

In drinking water distribution pipeline systems, the tap water quality is regulated by several biotic and abiotic factors, which can threaten the health of consumers. Stagnation is inevitable in the water distribution pipeline however, the combined effects of seasonal changes and stagnation on tap water quality are not well understood. Here, we investigated the seasonal variations in the chemical and biological quality of water after overnight stagnation for a period of one year. The results showed that the tap water quality deteriorated after overnight stagnation, with up to a 2.7-fold increase in the total iron concentrations. The total bacterial cell concentrations increased by 59-231% after overnight stagnation. The total cell and cell-bound adenosine triphosphate (ATP) of the stagnant water samples peaked in summer. In addition, Biolog analysis showed that the metabolic activities of microbes were higher in spring. The bacterial community based on Illumina Miseq DNA sequence analysis found that Proteobacteria dominated the drinking water bacterial community. The bacterial community structure varied significantly among different seasons, where the diversity and richness of the community were much higher in spring. Structural equation modeling (SEM) was constructed to determine the correlations between bacterial metabolic functions and the community structure. The redundancy analysis (RDA) indicated that the residual chlorine played a critical role in the construction of the bacterial community. Altogether, the overall findings from the present work provide novel insights into how the quality of tap water quality impacted by the seasonal changes and overnight stagnation.

Arsenic behavior across soil-water interfaces in paddy soils: Coupling, decoupling and speciation.

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.

A new coupon design for simultaneous analysis of in situ microbial biofilm formation and community structure in drinking water distribution systems.

This study presents a new coupon sampling device that can be inserted directly into the pipes within water distribution systems (WDS), maintaining representative near wall pipe flow conditions and enabling simultaneous microscopy and DNA-based analysis of biofilms formed in situ. To evaluate this sampling device, fluorescent in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE) analyses were used to investigate changes in biofilms on replicate coupons within a non-sterile pilot-scale WDS. FISH analysis demonstrated increases in bacterial biofilm coverage of the coupon surface over time, while the DGGE analysis showed the development of increasingly complex biofilm communities, with time-specific clustering of these communities. This coupon design offers improvements over existing biofilm sampling devices in that it enables simultaneous quantitative and qualitative compositional characterization of biofilm assemblages formed within a WDS, while importantly maintaining fully representative near wall pipe flow conditions. Hence, it provides a practical approach that can be used to capture the interactions between biofilm formation and changing abiotic conditions, boundary shear stress, and turbulent driven exchange within WDS.

Effects of anthropogenic subsidy and glyphosate on macroinvertebrates in streams.

Streams and surrounding terrestrial ecosystems are closely linked by numerous resource subsidies including anthropogenic subsidies which are increasingly entering streams due to intensive human activities. Also, streams are threatened by stressors such as glyphosate-the most widely used herbicide worldwide. However, the ecological consequences of anthropogenic subsidies and glyphosate on freshwaters are not fully understood. Here, we deployed leaf litter (Cinnamomum camphora) bags containing neither, either, or both treatments of anthropogenic carrion subsidy (chicken meat) and glyphosate (coated in agar) in four streams, which had different land use (i.e., forest, village, and suburban) in Huangshan, Anhui Province, China. We aimed to investigate the individual and combined effects of anthropogenic carrion subsidy and glyphosate on macroinvertebrates in streams and whether these effects differ with land use change. Macroinvertebrate communities significantly differed among streams: biodiversity index and total taxon richness were highest in village streams and lowest in suburban stream. Overall effects of carrion subsidy and glyphosate on macroinvertebrates were not significant. However, several taxa were affected in one or more streams by the individual or combined effects of carrion subsidy and glyphosate, indicating the importance of local community structure and physical habitats in driving the response of macroinvertebrates to carrion subsidy and glyphosate. Collectively, these results imply that the effects of carrion subsidy and glyphosate on macroinvertebrates are site-specific, and future studies should cover more streams and last longer time to better understand the ecological mechanisms driving such pattern.

Evaluating ecosystem functioning following river restoration: the role of hydromorphology, bacteria, and macroinvertebrates.

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.

Mixed-culture aerobic anoxygenic photosynthetic bacterial consortia reduce nitrate: Core species dynamics, co-interactions and assessment in raw water of reservoirs.

Three consortia of mixed-culture Aerobic Anoxygenic Photosynthetic Bacteria (AAPB) with excellent aerobic denitrifying ability were isolated from drinking water source reservoirs. The results showed that the removal of dissolved organic carbon (DOC) and nitrate nitrogen (NO3--N) by mixed-culture AAPB were higher than 90% and 99%, respectively. The Illumina MiSeq sequencing of pufM gene revealed that the dominant genera and their relative abundance changed over the culture periods. Sphingomonas sanxanigenens was the most dominant species observed at 9 h, whereas at 48 h, the most abundant species was Rhodobacter blasticus. A network analysis demonstrated that the co-interactions among the different genera were complex and variable. Mixed-culture AAPB removed more than 30% of NO3--N and 25% of DOC from the source water and this study suggests that mixed-culture AAPB can be regarded as a latent denitrifying microbial inoculum in the reservoir raw water treatment.