Fate of Naturally Dissolved Organic Matter and Synthetic Organic Compounds Subjected to Drinking Water Treatment Using Membrane, Activated Carbon, and UV/H2O2 Technologies.

Organic pollutants are toxic and are present in drinking water. The conventional processes of most water plants can basically meet the discharge standard. However, based on the improvement of the objective of organic pollutants control and the constant change of water characteristics, the results may not be ideal. This study evaluates the effectiveness of different treatments such as microfiltration, nanofiltration, reverse osmosis, activated carbon, and ultraviolet irradiation/H2O2 in terms of the removal of organic pollutants. Among the DOM results, nanofiltration, reverse osmosis, and activated carbon showed optimal performance due to the characteristics of processes and the compound properties. However, the risks of low-molecular-weight organic residue and byproduct formation are still present. Thirty-nine species of synthetic organic compounds (SOC) were qualitatively and semiquantitatively analyzed. Different technologies showed varying removal capabilities for SOC based on their properties and many substances coexisted leading to abnormal removal performances. These residual organics showed the characteristics of lower molecular weight, more hydrophilicity, further unknown impacts, and with risk of DBPs. Based on the above insights, possible methods can be rationally chosen for on-demand decontamination of organics in unconfined aquatic environment and long-time impact on water characteristics and human health also should be considered.

Seasonality Determines the Variations of Biofilm Microbiome and Antibiotic Resistome in a Pilot-Scale Chlorinated Drinking Water Distribution System Deciphered by Metagenome Assembly.

Understanding the biofilm microbiome and antibiotic resistome evolution in drinking water distribution systems (DWDSs) is crucial to ensure the safety of drinking water. We explored the 10 month evolution of the microbial community, antibiotic resistance genes (ARGs), mobile gene elements (MGEs) co-existing with ARGs and pathogenic ARG hosts, and the ARG driving factors in DWDS biofilms using metagenomics assembly. Sampling season was critical in determining the microbial community and antibiotic resistome shift. Pseudomonas was the primary biofilm colonizer, and biofilms diversified more as the formation time increased. Most genera tended to cooperate to adapt to an oligotrophic environment with disinfectant stress. Biofilm microbial community and antibiotic resistome assembly were mainly determined by stochastic processes and changed with season. Metagenome assembly provided the occurrence and fates of MGEs co-existing with ARGs and ARG hosts in DWDS biofilms. The abundance of ARG- and MGE-carrying pathogen Stenotrophomonas maltophilia was high in summer. It primarily harbored the aph(3)-IIb, multidrug transporter, smeD, and metallo-beta-lactamase ARGs, which were transferred via recombination. The microbial community was the most crucial factor driving the antibiotic resistance shift. We provide novel insights about the evolution of pathogens and ARGs and their correlations in DWDS biofilms to ensure the safety of drinking water.

Seasonal variations of microbial community and antibiotic resistome in a suburb drinking water distribution system in a northern Chinese city.

Antibiotic resistance genes (ARGs) are an emerging issue for drinking water safety. However, the seasonal variation of ARGs in drinking water distribution systems (DWDS) is still unclear. This work revealed the tempo-spatial changes of microbial community, ARGs, mobile genetic elements (MGEs) co-occurring with ARGs, ARG hosts in DWDS bulk water by means of metagenome assembly. The microbial community and antibiotic resistome varied with sampling season and site. Temperature, ammonia, chlorite and total plate count (TPC) drove the variations of microbial community structure. Moreover, environmental parameters (total organic carbon (TOC), chlorite, TPC and hardness) shifted antibiotic resistome. ARGs and MGEs co-occurring with ARGs showed higher relative abundance in summer and autumn, which might be attributed to detached pipe biofilm. In particular, ARG-bacitracin and plasmid were the predominant ARG and MGE, respectively. ARG hosts changed with season and site and were more diverse in summer and autumn. In winter and spring, Limnohabitans and Mycobacterium were the major ARG hosts as well as the dominant genera in microbial community. In addition, in summer and autumn, high relative abundance of Achromobacter and Stenotrophomonas were the hosts harboring many kinds of ARGs and MGEs at site in a residential zone (0.4 km from the water treatment plant). Compared with MGEs, microbial community had a greater contribution to the variation of antibiotic resistome. This work gives new insights into the dynamics of ARGs in full-scale DWDS and the underlying factors.

Molecular ecological networks reveal the spatial-temporal variation of microbial communities in drinking water distribution systems.

Microbial activity and regrowth in drinking water distribution systems is a major concern for water service companies. However, previous studies have focused on the microbial composition and diversity of the drinking water distribution systems (DWDSs), with little discussion on microbial molecular ecological networks (MENs) in different water supply networks. MEN analysis explores the potential microbial interaction and the impact of environmental stress, to explain the characteristics of microbial community structures. In this study, the random matrix theory-based network analysis was employed to investigate the impact of seasonal variation including water source switching on the networks of three DWDSs that used different disinfection methods. The results showed that microbial interaction varied slightly with the seasons but was significantly influenced by different DWDSs. Proteobacteria, identified as key species, play an important role in the network. Combined UV-chlorine disinfection can effectively reduce the size and complexity of the network compared to chlorine disinfection alone, ignoring seasonal variations, which may affect microbial activity or control microbial regrowth in DWDSs. This study provides new insights for analyzing the dynamics of microbial interactions in DWDSs.

Anaerobic sulfamethoxazole-degrading bacterial consortia in antibiotic-contaminated wetland sediments identified by DNA-stable isotope probing and metagenomics analysis.

Anaerobic degradation has been demonstrated as an important pathway for the removal of sulfonamide (SA) in contaminated environments, and identifying the microorganisms responsible for the degradation of SA is a key step in developing bioaugmentation approaches. In this study, we investigated the anaerobic degradation activity of three SA [sulfadiazine (SDZ), sulfamethazine (SMZ) and sulfamethoxazole (SMX)] and the associated bacterial community in wetland sediments contaminated by aquaculture (in Fujian Province, coded with FJ), livestock farming (in Sichuan Province, coded with SC), or rural wastewaters (in Guangdong Province, coded with GD). Additionally, the combination of DNA-stable isotope probing (SIP) with metagenomics was further applied to assess the active SA-degrading microbes using SMX as a model SA. Among SDZ, SMZ and SMX, only SMX could be effectively dissipated, and the degradation of SMX was relatively fast in the microcosms of sediments with higher levels of SA contamination (FJ and SC). The anaerobic biotransformation pathway of SMX was initiated by hydrogenation with the cleavage of the N-O bond on the isoxazole ring. DNA-SIP revealed that the in situ active anaerobic SMX-degraders (5, 18 and 3 genera in sediments FJ, SC and GD respectively) were dominated by Proteobacteria in sediments FJ and SC, but by Firmicutes (two Family XVIII members) in sediment GD. Mycobacterium, unclassified Burkholderiaceae and Rhodocyclaceae were identified as the dominant active SMX-degrading bacteria in both sediments FJ and SC. Higher proportions of antibiotic resistance gene and genes involved in various functional categories were observed in sediments FJ and SC.

In-situ active Bisphenol A-degrading microorganisms in mangrove sediments.

Bisphenol A (BPA), as both an endocrine disrupting compound and an important industrial material, is broadly distributed in coastal regions and may cause adverse effects on mangrove ecosystems. Although many BPA degraders have been isolated from various environments, the in-situ active BPA-degrading microorganisms in mangrove ecosystem are still unknown. In this study, DNA-based stable isotope probing in combination with high-throughput sequencing was adopted to pinpoint the microbes actually involved in BPA metabolism in mangrove sediments. Five bacterial genera were speculated to be associated with BPA degradation based on linear discriminant analysis (LDA) effect size (LEfSe) analysis, including Truepera, Methylobacterium, Novosphingobium, Rhodococcus and Rhodobacter. The in-situ BPA degraders were different between mudflat and forest sediments. The Shannon index of microbes in heavy fractions was significantly lower than that in light fractions. Besides, phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) demonstrated that the functional genes relevant to cytochrome P450, benzoate degradation, bisphenol degradation and citrate cycle were up-regulated significantly in in-situ BPA-degrading microbes. These findings greatly expanded the knowledge of indigenous BPA metabolic microorganisms in mangrove ecosystems.

Metagenomic insights into the profile of antibiotic resistomes in sediments of aquaculture wastewater treatment system.

To meet the rapidly growing global demand for aquaculture products, large amounts of antibiotics were used in aquaculture, which might accelerate the evolution of antibiotic-resistant bacteria (ARB) and the propagation of antibiotic genes (ARGs). In our research, we revealed the ARGs profiles, their co-occurrence with mobile genetic elements (MGEs), and potential hosts in sediments of a crab pond wastewater purification system based on metagenomic analysis. The residual antibiotic seems to increase the propagation of ARGs in the crab pond, but there was no clear relationship between a given antibiotic type and the corresponding resistance genes. The effect of aquaculture on sediment was not as profound as that of other anthropogentic activities, but increased the relative abundance of sulfonamide resistance gene. A higher abundance of MGEs, especially plasmid, increased the potential ARGs dissemination risk in crab and purification ponds. Multidrug and sulfonamide resistance genes had greater potential to transfer because they were more frequently carried by MGEs. The horizontal gene transfer was likely to occur among a variety of microorganisms, and various ARGs hosts including Pseudomonas, Acinetobacter, Escherichia, and Klebsiella were identified. Bacterial community influenced the composition of ARG hosts, and Proteobacteria was the predominant hosts. Overall, our study provides novel insights into the environmental risk of ARGs in sediments of aquaculture wastewater treatment system.

Effects of treatments and distribution on microbiome and antibiotic resistome from source to tap water in three Chinese geographical regions based on metagenome assembly.

Antibiotic resistance genes (ARGs) represent emerging environmental pollutants that present health risks. Drinking water supply systems (DWSSs), including sources to tap water, play crucial roles in the dissemination and propagation of ARGs. However, there was a paucity of knowledge on the relative abundance, diversity, mobility, and pathogenic hosts of ARGs in DWSSs from source to tap. Therefore, the effects of treatments and distributions on the microbial community and ARGs from three geographical regions (downstream areas of the Yellow, Yangtze, and Pearl Rivers) were elucidated in the present study. Treatment processes lowered the complexity of the microbial community network, whereas transportation increased it. The assembly mechanisms of the microbial community and antibiotic resistome were primarily driven by stochastic processes. Distribution greatly increased the contribution of stochastic processes. Multidrug ARGs (for example, multidrug transporter and adeJ) and bacitracin ARG (bacA) were the primary mobile ARGs in drinking water, as identified by the metagenomic assembly. Achromobacter xylosoxidans, Acinetobacter calcoaceticus, and Acinetobacter junii harbored diverse multidrug ARGs and mobile genetic elements (MGEs) (recombinases, integrases, and transposases) as potential pathogens and were abundant in the disinfected water. Environmental factors, including pH, chlorine, latitude, longitude, and temperature, influenced the ARG abundance by directly regulating the MGEs and microbial community diversity. This study provides critical information on the fate, mobility, host pathogenicity, and driving factors of ARGs in drinking water, which is conducive to ARG risk assessment and management to provide high-quality drinking water to consumers.

Effects of disinfectant type and dosage on biofilm's activity, viability, microbiome and antibiotic resistome in bench-scale drinking water distribution systems.

Drinking water distribution systems (DWDSs) are important for supplying high-quality water to consumers and disinfectant is widely used to control microbial regrowth in DWDSs. However, the disinfectant's influences on microbial community and antibiotic resistome in DWDS biofilms and the underlying mechanisms driving their dynamics remain elusive. The study investigated the effects of chlorine and chloramine disinfection on the microbiome and antibiotic resistome of biofilms in bench-scale DWDSs using metagenomics assembly. Additionally, the biofilm activity and viability were monitored based on adenosine triphosphate (ATP) and flow cytometer (FCM) staining. The results showed that both chlorine and chloramine disinfectants decreased biofilm ATP, although chloramine at a lower dosage (1 mg/L) could increase it. Chloramine caused a greater decrease in living cells than chlorine. Furthermore, the disinfectants significantly lowered the microbial community diversity and altered microbial community structure. Certain bacterial taxa were enriched, such as Mycobacterium, Sphingomonas, Sphingopyxis, Azospira, and Dechloromonas. Pseudomonas aeruginosa exhibited high resistance towards disinfectants. The disinfectants also decreased the complexity of microbial community networks. Some functional taxa (e.g., Nitrospira, Nitrobacter, Nitrosomonas) were identified as keystones in chloramine-treated DWDS microbial ecological networks. Stochasticity drove biofilm microbial community assembly, and disinfectants increased the contributions of stochastic processes. Chlorine had greater promotion effects on antibiotic resistance genes (ARGs), mobile genetic elements (MGEs) and ARG hosts than chloramine. The disinfectants also selected pathogens, such as Acinetobacter baumannii and Klebsiella pneumonia, and these pathogens also harbored ARGs and MGEs. Overall, this study provides new insights into the effects of disinfectants on biofilm microbiome and antibiotic resistome, highlighting the importance of monitoring and managing disinfection practices in DWDSs.

Enrichment of tetracycline-degrading bacterial consortia: Microbial community succession and degradation characteristics and mechanism.

Tetracycline (TC) is an antibiotic that is recently found as an emerging pollutant with low biodegradability. Biodegradation shows great potential for TC dissipation. In this study, two TC-degrading microbial consortia (named SL and SI) were respectively enriched from activated sludge and soil. Bacterial diversity decreased in these finally enriched consortia compared with the original microbiota. Moreover, most ARGs quantified during the acclimation process became less abundant in the finally enriched microbial consortia. Microbial compositions of the two consortia as revealed by 16 S rRNA sequencing were similar to some extent, and the dominant genera Pseudomonas, Sphingobacterium, and Achromobacter were identified as the potential TC degraders. In addition, consortia SL and SI were capable of biodegrading TC (initial 50 mg/L) by 82.92% and 86.83% within 7 days, respectively. They could retain high degradation capabilities under a wide pH range (4-10) and at moderate/high temperatures (25-40 °C). Peptone with concentrations of 4-10 g/L could serve as a desirable primary growth substrate for consortia to remove TC through co-metabolism. A total of 16 possible intermediates including a novel biodegradation product TP245 were detected during TC degradation. Peroxidase genes, tetX-like genes and the enriched genes related to aromatic compound degradation as revealed by metagenomic sequencing were likely responsible for TC biodegradation.

Antibiotic resistome alteration along a full-scale drinking water supply system deciphered by metagenome assembly: Regulated by seasonality, mobile gene elements and antibiotic resistant gene hosts.

Both drinking water treatment processes and distribution can lead to antibiotic resistome variation, yet the variation of antibiotic resistome in the whole drinking water supply system (DWSS) combined with seasonality remains unknown. In this study, microbial community, antibiotic resistome, mobile genetic elements (MGEs) co-existing with antibiotic resistance genes (ARGs) and ARG hosts would be explored along a DWSS for four seasons with metagenome assembly. Multidrug and bacitracin ARGs were dominant ARGs in DWSS. Integrase, plasmids, recombinase and transposase were major MGEs co-existing with ARGs. Filtration and disinfection treatments could alter the ARG relative abundance, mainly via changing the abundance of ARG hosts (Limnohabitans and Polynucleobacter), which was influenced by water total organic carbon (TOC) content. When TOC was relatively high, filtration could proliferate ARGs via promoting antibiotic resistance bacteria (ARB) but chlorine dioxide could decrease ARGs via killing ARB. Filtration played an important role in controlling ARGs by reducing ARB when TOC was relatively low. The stimulation effect of disinfection on ARGs existed in more oligotrophic environment. Distribution could enrich ARGs in higher temperature by increasing MGEs co-occurring with ARGs and diversifying ARG hosts. MGEs co-occurring with ARGs became more abundant and diverse in disinfected water in warmer seasons. Microbial community was the most important factor determining the antibiotic resistome along a DWSS. These findings extend the knowledge about how and why water treatment processes and pipe distribution shape drinking water antibiotic resistome in different seasons.

Deciphering of sulfonamide biodegradation mechanism in wetland sediments: from microbial community and individual populations to pathway and functional genes.

Figuring out the comprehensive metabolic mechanism of sulfonamide antibiotics (SA) is critical to improve and optimize SA removal in the bioremediation process, but relevant studies are still lacking. Here, an approach integrating metagenomic analysis, degraders' isolation, reverse transcriptional quantification and targeted metabolite determination was used to decipher microbial interactions and functional genes' characteristics in SA-degrading microbial consortia enriched from wetland sediments. The SA-degrading consortia could rapidly catalyze ipso-hydroxylation and subsequent reactions of SA to achieve the complete mineralization of sulfadiazine and partial mineralization of the other two typical SA (sulfamethoxazole and sulfamethazine). Paenarthrobacter, Achromobacter, Pseudomonas and Methylobacterium were identified as the primary participants for the initial transformation of SA. Among them, Methylobacterium could metabolize the heterocyclic intermediate of sulfadiazine (2-aminopyrimidine), and the owning of sadABC genes (SA degradation genes) made Paenarthrobacter have relatively higher SA-degrading activity. Besides, the coexistence of sadABC genes and sul1 gene (SA resistance gene) gave Paenarthrobacter a dual resistance mechanism to SA. The results of reverse transcription quantification further demonstrated that the activity of sadA gene was related to the biodegradation of SA. Additionally, sadABC genes were relatively conserved in a few Microbacteriaceae and Micrococcaceae SA-degraders, but the multiple recombination events caused by densely nested transposase encoding genes resulted in the differential sequence of sadAB genes in Paenarthrobacter genome. These new findings provide valuable information for the selection and construction of engineered microbiomes.

Seasonal variations of biofilm C, N and S cycling genes in a pilot-scale chlorinated drinking water distribution system.

Biofilms in drinking water distribution systems (DWDS) host diverse microorganisms. However, the functional attributes of DWDS biofilms and their associations with seasonality remain unclear. This study aims to characterize variations in the microbial metabolic traits of DWDS biofilms collected during different seasons, using a pilot-scale DWDS in dark under plug-flow conditions during one-year operation period. Network analysis was used to predict the functional gene hosts. The overall functional attributes determined by shotgun metagenomics exhibited significant differences among seasons. Genes associated with aromatic metabolism, fatty acid biosynthesis and degradation, and capsular extracellular polymeric substance (EPS) were significantly upregulated in summer owing to the higher temperatures and chlorine in the influent of the DWDS. Moreover, the pathways associated with nitrogen, sulfur, glycolysis, and tricarboxylic acid (TCA) cycling, as well as carbon fixation were reconstructed and displayed according to the sampling season. Nitrogen reduction pathways [dissimilatory nitrate reduction to ammonium (DNRA) 73 %, assimilatory nitrate reduction to ammonium (ANRA) 21 %] were identified in DWDS biofilms, but nitrogen oxidation pathways were not. Sulfur cycling were involved in diverse pathways and genes. Glycolysis and TCA cycling offered electron donors and energy sources for nitrogen and sulfur reduction in biofilms. Carbon fixation was observed in DWDS biofilms, with the predominant pathway for fixing carbon dioxide being the reductive citrate cycle (38 %). Constructed functional gene networks composed of carbon, nitrogen, and sulfur cycling-related genes demonstrated synergistic effects (Positive proportion: 63.52-71.09 %). In addition, from spring to autumn, the network complexity decreased and network modularity increased. The assembly mechanism of carbon, nitrogen and sulfur cycling-related genes was driven by stochastic processes for all samples. These results highlight the diverse functional genes in DWDS biofilms, their synergetic interrelationships, and the seasonality effect on functional attributes.

A comprehensive review on biodegradation of tetracyclines: Current research progress and prospect.

The release of tetracyclines (TCs) in the environment is of significant concern because the residual antibiotics may promote resistance in pathogenic microorganisms, and the transfer of antibiotic resistance genes poses a potential threat to ecosystems. Microbial biodegradation plays an important role in removing TCs in both natural and artificial systems. After long-term acclimation, microorganisms that can tolerate and degrade TCs are retained to achieve efficient removal of TCs under the optimum conditions (e.g. optimal operational parameters and moderate concentrations of TCs). To date, cultivation-based techniques have been used to isolate bacteria or fungi with potential degradation ability. Moreover, the biodegradation mechanism of TCs can be unveiled with the development of chemical analysis (e.g. UPLC-Q-TOF mass spectrometer) and molecular biology techniques (e.g. 16S rRNA gene sequencing, multi-omics sequencing, and whole genome sequencing). In this review, we made an overview of the biodegradation of TCs in different systems, refined functional microbial communities and pure isolates relevant to TCs biodegradation, and summarized the biodegradation products, pathways, and degradation genes of TCs. In addition, ecological risks of TCs biodegradation were considered from the perspectives of metabolic products toxicity and resistance genes. Overall, this article aimed to outline the research progress of TCs biodegradation and propose future research prospects.

Sulfonamide-metabolizing microorganisms and mechanisms in antibiotic-contaminated wetland sediments revealed by stable isotope probing and metagenomics.

Sulfonamide (SA) antibiotics are ubiquitous pollutants in livestock breeding and aquaculture wastewaters, which increases the propagation of antibiotic resistance genes. Microbes with the ability to degrade SA play important roles in SA dissipation, but their diversity and the degradation mechanism in the field remain unclear. In the present study, we employed DNA-stable isotope probing (SIP) combined with metagenomics to explore the active microorganisms and mechanisms of SA biodegradation in antibiotic-contaminated wetland sediments. DNA-SIP revealed various SA-assimilating bacteria dominated by members of Proteobacteria, such as Bradyrhizobium, Gemmatimonas, and unclassified Burkholderiaceae. Both sulfadiazine and sulfamethoxazole were dissipated mainly through the initial ipso-hydroxylation, and were driven by similar microbes. sadA gene, which encodes an NADH-dependent monooxygenase, was enriched in the 13C heavy DNA, confirming its catalytic capacity for the initial ipso-hydroxylation of SA in sediments. In addition, some genes encoding dioxygenases were also proposed to participate in SA hydroxylation and aromatic ring cleavage based on metagenomics analysis, which might play an important role in SA metabolism in the sediment ecosystem when Proteobacteria was the dominant active bacteria. Our work elucidates the ecological roles of uncultured microorganisms in their natural habitats and gives a deeper understanding of in-situ SA biodegradation mechanisms.

Can we shape microbial communities to enhance biological activated carbon filter performance?

A new focus on biofiltration has emerged that aims to shape microbial communities to improve treatment efficacy. It is therefore necessary to understand the linkages between microbial community structure and biofilter function. However, the assembly and interaction of microbial communities in biological activated carbon (BAC) filters are unknown. In this study, we selected one coal-based granular activated carbon (GAC), GAC-13, with simultaneously developed micropore and micro-level macropore volume used for a bench-scale BAC column experiment, and compared it with other coal-based GACs and wood-based GAC in terms of the dissolved organic carbon (DOC) removal and microbial community characteristics. The results showed that there was no difference between the DOC removal efficiency of BAC-13 and the other two coal-based BAC filters with high iodine value in the period dominated by adsorption, while the DOC removal efficiency of BAC-13 (64.7±0.6%) was significantly higher than that of other BAC filters (36.3±0.8-54.1±0.4%) with a difference of 0.3-0.7 mg/L in DOC during the steady state. The bacterial communities were strongly assembled by deterministic rather than stochastic factors, where the surface polarity of GAC had a greater effect on the microbial communities than its physical properties. The corresponding co-occurrence network revealed that microbes in the BAC filter may be more cooperative than competitive. The keystone bacterium Hyphomicrobium, which had a relatively low abundance, contributed 0.3-1% more to the most abundant functions and produced 5-21 proteins/(g·GAC) more than the dominant bacterium Sphingobium. The metaproteomic-based approach could provide more accurate information regarding the contributions of different species to metabolic functions. The pore size distribution of GAC was found to be an important factor in determining BAC filter performance; the most important pore sizes were micropores and micro-level macropores (0.2-10 µm and >100 µm in diameter), and the latter impacted the abundance of keystone species. Overall, our findings provide new insights into shaping microbial communities by optimizing pore size structure to improve BAC performance, especially the abundance of keystone species.

Bisphenol A biodegradation differs between mudflat and mangrove forest sediments.

Bisphenol A (BPA) is one of the widely detected endocrine disrupting chemicals in coastal sediment. Biodegradation is a vital pathway of BPA elimination in sediment. However, the impact of vegetation on BPA degradation in coastal sediment is still unclear. In this study, the differences of BPA biodegradation and the functional microbial community and metabolic pathway were explored between mangrove forest and mudflat sediments. A nearly complete BPA attenuation was detected in 4 days in mudflat sediment but 8 days in forest sediment. Bacterial abundance varied greatly in different sediment types. Bacterial community structure changed with BPA biodegradation, dependent on sediment type. During the degradation, the proportions of Alphaproteobacteria and Gammaproteobacteria were higher in BPA amended microcosms than in un-amended microcosms. With BPA biodegradation, a substantial increase in Novosphingobium and Croceicoccus occurred in forest sediment and mudflat sediment, respectively. Additionally, two divergent BPA biodegradation pathways were proposed based on functional annotation and KEGG pathway database. The abundance of functional genes also varied with BPA biodegradation, dependent on sediment type. Gene pcaGH decreased, while genes ligK and pcaD increased in both sediment types. Gene pcaB showed a remarkable increase in forest sediment but a decrease in mudflat sediment. Therefore, BPA degradation and the associated microbial community and metabolic pathway differed between mudflat and mangrove forest sediments.

Microbial composition and diversity of drinking water: A full scale spatial-temporal investigation of a city in northern China.

The microbiological water quality of drinking water distribution systems (DWDSs) is of primary importance for public health. The detachment of biofilm attached on the pipe wall attribution to water source switch and the occurrence of potentially pathogenic chlorine-resistant bacteria (CRB) under chlorine disinfection get lots of attention. Studies examining microbial communities after the water source switch, particularly in low-salinity water, have been scant. The UV­chlorine combined disinfection applied in one of the investigated drinking water plants provided insight into the control of CRBs. We applied high-throughput sequencing of the 16S rRNA gene to characterize the bacterial communities of the DWDS in northern China over 1 year. A network comprising four different DWDSs was sampled at 48 sites every season (temperate continental monsoon climate), and the impact of key spatial-temporal and physicochemical parameters was investigated. Overall, the entire bacterial community was not significantly different among the four DWDSs (spatial parameter) but varied with seasons (temporal parameter). The switch in water sources might increase the relative abundance of potentially opportunistic pathogens in DWDSs. UV­chlorine combined disinfection can decrease community diversity and is likely to control the growth of potential opportunistic pathogens in DWDSs.

Influences of hexafluoropropylene oxide (HFPO) homologues on soil microbial communities.

Hexafluoropropylene oxide (HFPO) homologues, as emerging perfluoroalkyl substances (PFASs) to replace legacy PFASs, have wide applications in the organofluorine industry and have been detected in the global environment. However, it is still unclear what effect HFPO homologues will exert on microbial abundance, community structure and function. The objective of this study was to assess potential impacts of HFPO homologue acids on archaea, bacteria, and ammonia-oxidizing archaea (AOA) and bacteria (AOB) in the soil environment. Grassland soil microcosms were supplemented with low (0.1 mg/kg) or high (10 mg/kg) dosages of dimer, trimer and tetramer acids of HFPO (HFPO-DA, HFPO-TA, and HFPO-TeA), respectively. The amendment of HFPO homologues acids initially decreased the abundance of archaea and bacteria but increased them in the later period. The addition of HFPO homologues acids raised AOA abundance but restrained AOB growth during the whole incubation. AOA and AOB community structures showed considerable variations. Potential nitrifying rate (PNR) showed an increase in the initial period followed by a decline in the later period. HFPO-DA had a lasting and suppressive effect on AOB and PNR even at a nearly environmental level. Overall, HFPO homologues with different carbon chain lengths had different impacts on soil microbial community and ammonia oxidation.