Is it really safe to replace decabromodiphenyl ether (BDE209) with decabromodiphenyl ethane (DBDPE)?: A perspective from hepatotoxicity.

In this paper, the hepatocytotoxicity and aryl hydrocarbon receptor (AHR) activity of decabromodiphenyl ethane (DBDPE), decabromodiphenyl ether (BDE209) and other 18 analogues were evaluated in vitro using human normal liver cell L02. These dioxin-like compounds showed differential hepatocytotoxicity (EC50  = 0.38-17.87 mg/L) and AHR activity (EROD activity = 4.53-46.35 U/µg). In silico study indicated the distance of π-π bonds between the benzene ring of compounds and residue Phe234 of AHR played a key role in the binding of AHR, and the substituents on the benzene ring also influenced the activity. Combining molecular biology and bioomics, the comprehensive investigations on the hepatotoxic mechanisms have demonstrated the AHR signaling pathway was the key mediation mechanism for the hepatotoxicity of DBDPE/BDE209. The cytochrome P450s (CYP2 family) mediated formation of reactive oxygenated intermediates might be the dominant toxic mechanism, which could produce oxidative stress or cause genotoxicity. Although the experimental toxicity of DBDPE was smaller relative to BDE209, the health risk of DBDPE may be much greater than we expected, due to the high potential to form a variety of dioxin-like intermediates by microbial oxidation of ethyl group. Therefore, whether it is really safe to replace BDE209 with DBDPE is a debatable question, and more ecotoxicological and health data are needed to clarify this issue.

Effect of Nano-Silver on Formation of Marine Snow and the Underlying Microbial Mechanism.

Roller experiments were conducted to explore the effect of nano-silver on the formation of marine snow and the underlying microbial mechanism. With the increasing concentration of nano-Ag from 1 ng/L to 1 mg/L, the formation and aggregation of marine snow particles were solidly suppressed in a dose-dependent pattern. Moreover, the formed marine snows tended to be thinner fibrous particles with smaller size and increased edge smoothness and compactness in the presence of nano-Ag. The microbial analyses indicated that nano-Ag not only inhibited the development of biomass but also changed the species composition and functional profile of the microbial community. Nano-Ag obviously inhibited most of the abundant species, except for some myxobacteria, which is unfavorable for the microbial community stability. For the microbial functions, some major biological processes including the growth, metabolic, and cellular processes were also inhibited by the high dosage of nano-Ag. The strong microbial inhibition of nano-Ag would contribute to the suppression on the formation of marine snow. Specifically, the function genes of extracellular polymeric substance synthesis and secretion were significantly reduced by nano-Ag, which might be the key and straight microbial factor in suppressing the formation of marine snow.

A metagenomic-based method to study hospital air dust resistome.

As a symbol of the defense mechanisms that bacteria have evolved over time, the genes that make bacteria resist antibiotics are overwhelmingly present in the environment. Currently, bacterial antibiotic resistance genes (ARGs) in the air are a serious concern. Previous studies have identified bacterial communities and summarized putative routes of transmissions for some dominant hospital-associated pathogens from hospital indoor samples. However, little is known about the possible indoor air ARG transportation. In this study, we mainly surveyed air-conditioner air dust samples under different airflow conditions and analyzed these samples using a metagenomic-based method. The results show air dust samples exhibited a complex resistome, and the average concentration is 0.00042 copies/16S rRNA gene, which is comparable to some other environments. The hospital air-conditioners can form resistome over time and accumulate pathogens. In addition, our results indicate that the Outpatient hall is one of the main ARG transmission sources, which can distribute ARGs to other departments (explains >80% resistome). We believe that the management should focus on ARG carrier genera such as Staphylococcus, Micrococcus, Streptococcus, and Enterococcus in this hospital and our novel evidence-based network strategy proves that plasmid-mediated ARG transfer can occur frequently. Overall, these results provide insights into the characteristics of air dust resistome and possible route for how ARGs are spread in air.

Spatiotemporal distribution, risk assessment and source appointment of metal(loid)s in water and sediments of Danjiangkou Reservoir, China.

Danjiangkou Reservoir is the biggest artificial reservoir in China. But spatiotemporal distribution and risks of metal(loid)s in it were still unclear after the operation of Middle Route of South-to-North Water Diversion Project. In this study, distribution pattern of fifteen metal(loid)s in the Danjiangkou Reservoir was investigated. It was shown that metal(loid)s concentrations in the water were much lower than the drinking water quality standards in China, while Sb, Co, Cd and Cr were identified as the major pollutants in the sediments. Environment-metal(loid)s correlation analysis revealed total organic carbon, sulfate, temperature, dissolved oxygen and total phosphorus markedly controlled metal(loid)s distribution in the water, while organic carbon, total phosphorus and ammonia nitrogen shaped their distribution in the sediments. Results of risk assessment further revealed that the sediments of Danjiangkou Reservoir were minor to moderate polluted, and Sb, Cd exhibited the highest potential ecological risk. Additionally, source identification showed agricultural activities (25.3%), industrial and mining activities (17.5%) and natural processes (57.2%) were the dominant sources of metal(loid)s burden in the sediments. Overall, the results are of significance to understanding the ecological risk and pollution sources in the Danjiangkou Reservoir, which is essential for the effective management of metal(loid)s pollution.

Active ammonia-oxidizing bacteria and archaea in wastewater treatment systems.

Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are two microbial groups mediating nitrification, yet little is presently known about their abundances and community structures at the transcriptional level in wastewater treatment systems (WWTSs). This is a significant issue, as the numerical abundance of AOA or AOB at the gene level may not necessarily represent their functional role in ammonia oxidation. Using amoA genes as molecular markers, this study investigated the transcriptional abundance and community structure of active AOA and AOB in 14 WWTSs. Quantitative PCR results indicated that the transcriptional abundances of AOB amoA (averaged: 1.6 × 108 copies g-1 dry sludge) were higher than those of AOA (averaged: 3.4 × 107 copies g-1 dry sludge) in all WWTSs despite several higher abundances of AOA amoA at the gene level. Moreover, phylogenetic analysis demonstrated that Nitrosomonas europaea and unknown clusters accounted for 37.66% and 49.96% of the total AOB amoA transcripts, respectively, suggesting their dominant role in driving ammonia oxidation. Meanwhile, AOA amoA transcripts were only successfully retrieved from 3 samples, and the Nitrosospaera sister cluster dominated, accounting for 83.46%. Finally, the substrate utilization kinetics of different AOA and AOB species might play a fundamental role in shaping their niche differentiation, community composition, and functional activity. This study provides a basis for evaluating the relative contributions of ammonia-oxidizing microorganisms (AOMs) to nitrogen conversions in WWTSs.

Effect of modified basic oxygen furnace slag on the controlled release of nitrate nitrogen and the functional microbial community in soil.

The specific surface area and active adsorption sites of basic oxygen furnace (BOF) slag increase after BOF modification. The addition of modified BOF slag to the soil may enable the control of nitrate nitrogen (NO3-N) leaching and also affect the functional microflora in the soil. In this study, soil column leaching experiments were conducted to explore the effects of adding modified slag to the soil on the controlled release of NO3-N and the main functional microbial communities involved in nitrification and denitrification processes. The experimental design included seven column groups: a soil control group (CT); soil groups with 2.5%, 5%, and 10% raw slag (S1, S2, S3); and soil groups with 2.5%, 5%, and 10% modified slag (MS1, MS2, MS3) that were subjected to three cycles of leaching, each of which were comprised of five leaching treatments. After the three cycles of leaching, significantly less NO3-N had leached from the modified slag group compared to the CT and the raw slag groups (P < 0.05). Although both slag treatments increased soil pH and decreased the oxidation reduction potential of the soil leaching solution, the addition of modified slag had less effect on soil pH than the addition of raw slag. During column leaching, the group with modified slag had a higher gene abundance of functional microflora compared with the group with raw slag. Similarly, the modified slag group had a higher diversity and richness of denitrifying bacteria, ammonia-oxidizing archaea, and ammonia-oxidizing bacteria than the raw slag group. In conclusion, the addition of modified slag to soil effectively decreased the NO3-N leaching and had relatively little effect on the functional microbial community in the soil.

Dominant role of ammonia-oxidizing bacteria in nitrification due to ammonia accumulation in sediments of Danjiangkou reservoir, China.

Surface sediments are the inner source of contaminations in aquatic systems and usually maintain aerobic conditions. As the key participators of nitrification process, little is known about the activities and contributions of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in the surface sediments. In this study, we determined the net and potential nitrification rates and used 1-octyne as an AOB specific inhibitor to detect the contributions of AOA and AOB to nitrification in surface sediments of Danjiangkou reservoir, which is the water source area of the middle route of South-to-North Water Diversion Project in China. Quantitative PCR and Illumina high-throughput sequencing were used to evaluate the abundance and diversity of the amoA gene. The net and potential nitrification rates ranged from 0.42 to 1.93 and 2.06 to 8.79 mg N kg-1 dry sediments d-1, respectively. AOB dominated in both net and potential nitrification, whose contribution accounted for 52.7-78.6% and 59.9-88.1%, respectively. The cell-specific ammonia oxidation rate calculation also revealed the cell-specific rates of AOB were higher than that of AOA. The Spearman's rank correlation analysis suggested that ammonia accumulation led to the AOB predominant role in net nitrification activity, and AOB abundance played the key role in potential nitrification activity. Furthermore, phylogenetic analysis suggested AOB were predominantly characterized by the Nitrosospira cluster, while AOA by the Nitrososphaera and Nitrososphaera sister clusters. This study will help us to better understand the contributions and characteristics of AOA and AOB in aquatic sediments and provide improved strategies for nitrogen control in large reservoirs.

When antibiotics encounter microplastics in aquatic environments: Interaction, combined toxicity, and risk assessments.

Antibiotics and microplastics (MPs), known as emerging pollutants, are bound to coexist in aquatic environments due to their widespread distribution and prolonged persistence. To date, few systematic summaries are available for the interaction between MPs and antibiotics in aquatic ecosystems, and a comprehensive reanalysis of their combined toxicity is also needed. Based on the collected published data, we have analyzed the source and distribution of MPs and antibiotics in global aquatic environments, finding their coexistence occurs in a lot of study sites. Accordingly, the presence of MPs can directly alter the environmental behavior of antibiotics. The main influencing factors of interaction between antibiotics and MPs have been summarized in terms of the characteristics of MPs and antibiotics, as well as the environmental factors. Then, we have conducted a meta-analysis to evaluate the combined toxicity of antibiotics and MPs on aquatic organisms and the related toxicity indicators, suggesting a significant adverse effect on algae, and inapparent on fish and daphnia. Finally, the environmental risk assessments for antibiotics and MPs were discussed, but unfortunately the standardized methodology for the risk assessment of MPs is still challenging, let alone assessment for their combined toxicity. This review provides insights into the interactions and environment risks of antibiotics and MPs in the aquatic environment, and suggests perspectives for future research.

Eutrophication impacts the distribution and functional traits of viral communities in lakes.

Viruses play a crucial role in aquatic ecosystems by regulating microbial composition and impacting biogeochemical cycling. While the response of viral diversity to the trophic status has been preliminarily explored in lake ecosystems, there is limited integrated exploration of the biogeography of viruses, host associations, and the auxiliary metabolic genes (AMGs), particularly for plateau lakes. Therefore, this research investigated the viral biogeography, virus-host association, and AMGs in the surface waters of 11 lakes varying in trophic levels (eutrophic and oligo-mesotrophic) in the Yunnan-Guizhou plateau region of China. A total of 73,105 viral operational taxonomic units were obtained from 11 samples, with 84.8 % remaining unannotated at the family level, indicating a predominance of novel viruses within these lakes. The most abundant viral family was Kyanoviridae (24.4 %), recognized as a common cyanophage. The vast majority of cyanobacteria and several eukaryotic algae were predicted as hosts for the viruses, with a lytic lifestyle predominating the life strategy of these cyanophages, implying the potential influence of the virus on algae. The viral community structure significantly correlated with both trophic status and the bacterial community. The structure equation model analysis revealed chlorophyll a was the primary factor affecting viral communities. Moreover, numerous AMGs linked to carbon metabolism, phosphorus metabolism, sulfur metabolism, and photosynthesis were found in these lakes, some of which showed virus preference for the trophic statuses, suggesting a vital role of the virus in driving biogeochemical cycling in the lake crossing different nutrient levels. In addition, a restricted presence of viruses was found to infect humans or harbor antibiotic resistance genes in the lakes, suggesting a subtle yet potential link to human health. Overall, these findings offer insights into the response of viral communities to eutrophication and their potential role in biogeochemical cycling and controlling algal propagation.

Low temperature acclimation of electroactive microorganisms may be an effective strategy to enhance the toxicity sensing performance of microbial fuel cell sensors.

Microbial fuel cell (MFC) sensing is a promising method for real-time detection of water biotoxicity, however, the low sensing sensitivity limits its application. This study adopted low temperature acclimation as a strategy to enhance the toxicity sensing performance of MFC biosensor. Two types of MFC biosensors were started up at low (10 °C) or warm (25 °C) temperature, denoted as MFC-Ls and MFC-Ws respectively, using Pb2+ as the toxic substance. MFC-Ls exhibited superior sensing sensitivities towards Pb2+ compared with MFC-Ws at both low (10 °C) and warm (25 °C) operation temperatures. For example, the inhibition rate of voltage of MFC-Ls was 22.81 % with 1 mg/L Pb2+ shock at 10 °C, while that of MFC-Ws was only 5.9 %. The morphological observation showed the anode biofilm of MFC-Ls had appropriate amount of extracellular polymer substances, thinner thickness (28.95 µm for MFC-Ls and 41.58 µm for MFC-Ws) and higher proportion of living cells (90.65 % for MFC-Ls and 86.01 % for MFC-Ws) compared to that of MFC-Ws. Microbial analysis indicated the enrichment of psychrophilic electroactive microorganisms and cold-active enzymes as well as their sensitivity to Pb2+ shock was the foundation for the effective operation and good performance of MFC-Ls biosensors. In conclusion, low temperature acclimation of electroactive microorganisms enhanced not only the sensitivity but also the temperature adaptability of MFC biosensors.

In situ Nanopore sequencing reveals metabolic characteristics of the Qilian glacier meltwater microbiome.

Nanopore metagenomic sequencing enables rapid annotating microbiological ecosystems, and the previous glacier-related sequencing applications (e.g., targeted ice sheets, ice lake, and cryoconite holes) inspire us to explore high-altitude glacier meltwater at Qilian Mountain, China (3000 to 4000 m above sea level, MASL). Our findings suggest that (1) despite only several hundred meters apart, the microbial communities and functionalities are quite different among vertical alpine distributions; (2) the high-altitude Qilian meltwater microbiome serve several main metabolic functions, including sulfur oxidation, selenite decomposing, photosynthesis, energy production, enzymic, and UV tolerant activities. Meanwhile, our Nanopore metagenomic results indicate that the microbial classifications and functionalities (e.g., chaperones, cold-shock, specific tRNA species, oxidative stress, and resistance to toxic compounds) of Qilian meltwater are highly consistent with the other glacial microbiome, emphasizing that only certain microbial species can survive in the cold environment and the molecular adaptions and lifestyles remain stable all over the world. Besides, we have shown Nanopore metagenomic sequencing can provide reliable prokaryotic classifications within or among studies, which therefore can encourage more applications in the field given faster turnaround time. However, we recommend accumulating at least 400 ng nucleic acids (after extraction) and maximizing Nanopore library preparation efficiency before on-site sequencing to obtain better resolutions.

The distinct resistance mechanisms of cyanobacteria and green algae to sulfamethoxazole and its implications for environmental risk assessment.

Cyanobacteria and green algae are the OECD recommended test organisms for environmental toxicity assessments of chemicals. Whether the differences in these two species' responses to the identical chemical affect the assessment outcomes is a question worth investigating. Firstly, we investigated the distinct resistance mechanisms of Synechococcus sp. (cyanobacteria) and R. subcapitata (green algae) to sulfamethoxazole (SMX). The antioxidant system analysis demonstrated that R. subcapitata mainly relies on enhancing the activity of first line defense antioxidants, including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), which is the most powerful and efficient response to get rid of ROS, whereas Synechococcus sp. depends upon increasing the activity of glutathione-S-transferase (GST) and GPx to resist oxidative stress. Besides, a total 7 transformation products (TPs) of SMX were identified in R. subcapitata culture medium. The analysis of conjectural transformation pathways and the predicted toxicity indicates that R. subcapitata could relieve SMX toxicity by degrading it to low eco-toxic TPs. Additionally, we summarized numerous exposure data and assessed the environmental risk of various antibiotics, revealing an inconsistent result for the same type of antibiotic by using cyanobacteria and green algae, which is most likely due to the different resistance mechanisms. In the future, modified indicators or comprehensive assessment methods should be considered to improve the rationality of environmental toxicity assessments.

Interaction of silver nanoparticles with marine/lake snow in early formation stage.

Marine and lake snows play an important ecological role in aquatic systems, and recent researches have also revealed their interactions with various pollutants. In this paper, the interaction of silver nanoparticles (Ag-NPs), a typical nano-pollutant, with marine/lake snow in the early formation stage was investigated by roller table experiments. Results indicated Ag-NPs promoted the accumulation of larger marine snow flocs while inhibited the development of lake snow. The promotion effect of AgNPs might be attributed to their oxidative dissolution into low-toxic silver chloride complexes in seawater, and the subsequent incorporation into marine snow, which would enhance the rigidity and strength of larger flocs and favor the development of biomass. Conversely, Ag-NPs mainly existed in the form of colloidal nanoparticles in lake water and their strong antimicrobial effect suppressed the growths of biomass and lake snow. In addition, Ag-NPs could also affect the microbial community of marine/lake snow, including impact on microbial diversity, and elevation on abundances of extracellular polymeric substances (EPS) synthesis genes and silver resistance genes. This work has deepened our understanding of the fate and ecological effect of Ag-NPs via the interaction with marine/lake snow in aquatic environments.

Planktonic/benthic Bathyarchaeota as a "gatekeeper" enhance archaeal nonrandom co-existence and deterministic assembling in the Yangtze River.

Archaea, the third proposed domain of life, mediate carbon and nutrient cycling in global natural habitats. Compared with bacteria, our knowledge about archaeal ecological modes in large freshwater environments subject to varying natural and human factors is limited. By metabarcoding analysis of 303 samples, we provided the first integrate biogeography about archaeal compositions, co-existence networks, and assembling processes within a 6000 km continuum of the Yangtze River. Our study revealed that, among the major phyla, water samples owned a higher proportion of Thaumarchaeota (62.8%), while sediments had higher proportions of Euryarchaeota (33.4%) and Bathyarchaeota (18.8%). A decline of polarization in phylum abundance profile was observed from plateau/mountain/hill to basin/plain areas, which was attributed to the increase of nutrients and metals. Planktonic and benthic Bathyarchaeota tended to co-occur with both major (e.g., methanogens or Thermoplasmata) and minor (e.g., Asgard or DPANN) taxa in the non-random networks, harboring the highest richness and abundances of keystone species and contributing the most positively to edge number, node degree, and nearest neighbor degree. Furthermore, we noted significantly positive contributions of Bathyarchaeota abundance and network complexity to the dominance of deterministic process in archaeal assembly (water: 65.3%; sediments: 92.6%), since higher carbon metabolic versatility of Bathyarchaeota would benefit archaeal symbiotic relations. Stronger deterministic assembling was identified at the lower-reach plain, and higher concentrations of ammonium and aluminum separately functioning as nutrition and agglomerator were the main environmental drivers. We lastly found that the Three Gorges Dam caused a simultaneous drop of benthic Bathyarchaeota abundance, network co-existence, and deterministic effects immediately downstream due to riverbed erosion as a local interference. These findings highlight that Bathyarchaeota are a "gatekeeper" to promote fluvial archaeal diversity, stability, and predictability under varying macroscopic and microscopic factors, expanding our knowledge about microbial ecology in freshwater biogeochemical cycling globally.

Effect of chlorine disinfectant influx on biological sewage treatment process under the COVID-19 pandemic: Performance, mechanisms and implications.

Since the onset of the COVID-19 Pandemic, large amounts of chlorine-containing disinfectants have been used to interrupt the spread of SARS-CoV-2 and residual chlorine eventually entered the hospital or municipal sewage treatment facilities. However, little is known about the effect of chlorine influx on the biological sewage treatment process. Here we investigated the effect of chlorine on the microbiome and the mechanism of microbial chlorine resistance in the activated sludge of the aerobic treatment process, using metagenomic and metatranscriptomic sequencing. We found that chlorine could negatively impact the aerobic treatment performance regarding nitrogen/COD removal with a dose-dependent effect, and the dual effects of chlorine dose and interaction time differentiated the microbial community in activated sludge. The decline of nitrogen/COD removal was attributed to the compressed activity of functional microorganisms, such as the ammonia oxidation bacteria, under chlorinated conditions, and the damage cannot be recovered in a short term. In addition, some microorganisms could survive in chlorinated conditions by up-regulating the chlorine resistance genes (CRGs) expression (approximately 1.5 times) and stimulating new CRGs expression. In particular, species Acinetobacter johnsonii could resist high concentrations of chlorine through various mechanisms, especially the overexpression of efflux pump function encoded by qac genes play a key role. Based on these results, considering the persistence of the epidemic and extensive use of chlorine disinfectants, it cannot be ignored that large amounts of residual chlorine are entering the biological treatment facility, and strictly de-chlorination measures or microbial chlorine resistance regulations before entering should be implemented.

May microbial ecological baseline exist in continental groundwater?

BACKGROUND: Microbes constitute almost the entire biological community in subsurface groundwater and play an important role in ecological evolution and global biogeochemical cycles. Ecological baseline as a fundamental reference with less human interference has been investigated in surface ecosystems such as soils, rivers, and ocean, but the existence of groundwater microbial ecological baseline (GMEB) is still an open question so far. RESULTS: Based on high-throughput sequencing information derived from national monitoring of 733 newly constructed wells, we find that bacterial communities in pristine groundwater exhibit a significant lateral diversity gradient and gradually approach the topsoil microbial latitudinal diversity gradient with decreasing burial depth of phreatic water. Among 74 phyla dominated by Proteobacteria in groundwater, Patescibacteria act as keystone taxa that harmonize microbes in shallower aquifers and accelerate decline in bacterial diversity with increasing well-depth. Decreasing habitat niche breadth with increasing well-depth suggests a general change in the relationship among key microbes from closer cooperation in shallow to stronger competition in deep groundwater. Unlike surface-water microbes, microbial communities in pristine groundwater are predominantly shaped by deterministic processes, potentially associated with nutrient sequestration under dark and anoxic environments in aquifers. CONCLUSIONS: By unveiling the biogeographic patterns and mechanisms controlling the community assembly of microbes in pristine groundwater throughout China, we firstly confirm the existence of GMEB in shallower aquifers and propose Groundwater Microbial Community Index (GMCI) to evaluate anthropogenic impact, which highlights the importance of GMEB in groundwater water security and health diagnosis. Video Abstract.

Assisted Selection of Biomarkers by Linear Discriminant Analysis Effect Size (LEfSe) in Microbiome Data.

There is growing attention toward closed biological genomes in the environment and in health. To explore and reveal the intergroup differences among different samples or environments, it is crucial to discover biomarkers with statistical differences among groups. The application of Linear discriminant analysis Effect Size (LEfSe) can help find good biomarkers. Based on the original genome data, quality control, and quantification of different sequences based on taxa or genes are carried out. First, the Kruskal-Wallis rank test was used to distinguish between specific differences among statistical and biological groups. Then, the Wilcoxon rank test was performed between the two groups obtained in the previous step to assess whether the differences were consistent. Finally, a linear discriminant analysis (LDA) was conducted to evaluate the influence of biomarkers on significantly different groups based on LDA scores. To sum up, LEfSe provided the convenience for identifying genomic biomarkers that characterize statistical differences among biological groups.

Enhanced removal efficiency of sulfamethoxazole by acclimated microalgae: Tolerant mechanism, and transformation products and pathways.

This study utilized sulfamethoxazole (SMX) acclimatization to enhance the tolerance and biodegradation capacity of Chlorella vulgaris. Compared to wild C. vulgaris, the growth inhibition and oxidative damage induced by SMX evidently decreased in acclimated C. vulgaris, and meanwhile photosynthetic and antioxidant activities were significantly promoted. The physiological analyses with the aid of principal component analysis revealed the increase of catalase and glutathione reductase activities was the critical tolerant mechanism of acclimated C. vulgaris. As the consequence, the acclimated C. vulgaris exhibited enhanced efficiency and (pseudo-first-order) kinetic rate for removal of SMX. The distribution analysis of residual SMX demonstrated the biodegradation was the major removal mechanism of SMX by C. vulgaris, while bioadsorption and bioaccumulation made pimping contributions. During the degradation process of SMX, nine transformation products (TPs) were identified. Based on the identified TPs, a possible transformation pathway was proposed.

Rare biosphere regulates the planktonic and sedimentary bacteria by disparate ecological processes in a large source water reservoir.

The bacteria in the water column and surface sediments are inherently intertwined and inseparable in aquatic ecosystems, yet little is known about the integrated spatiotemporal dynamics and driving mechanisms of both planktonic and sedimentary bacterial communities in reservoirs. By investigating the planktonic and sedimentary bacteria during four seasons from 88 samples of 11 representative sites across the Danjiangkou reservoir, we depicted an integrated biogeographic pattern of bacterial communities in the water source of the world's largest water diversion project. Our study revealed both planktonic (mantel r = 0.502, P = 0.001) and sedimentary (mantel r = 0.131, P = 0.009) bacterial communities were significantly correlated with environmental heterogeneity, but a weak disparity along spatial heterogeneity, and the significant seasonal dynamics of planktonic (mantel r = 0.499, P = 0.001) rather than sedimentary bacteria. Particularly, rare biosphere played a main role in determining the community succession in the reservoir. It not only exhibited a more striking environmental separation than abundant taxa but also was an essential part in mediating spatiotemporal shifts of planktonic bacteria and maintaining the stability of bacterial community. These rare bacteria were respectively mediated by stochastic (62.68%) and selective (79.60%) processes in water and sediments despite abundant taxa being largely determined by stochastic processes (86.88-93.96%). Overall, our study not only fills a gap in understanding the bacterial community dynamics and underlying drivers in source water reservoirs, but also highlights the particular importance of rare bacteria in mediating biogeochemical cycles in world's large reservoir ecosystems.

Nanopore-based long-read metagenomics uncover the resistome intrusion by antibiotic resistant bacteria from treated wastewater in receiving water body.

Wastewater treatment plant (WWTP) effluent discharge could induce the resistome enrichment in the receiving water environments. However, because of the general lack of a robust antibiotic-resistant bacteria (ARB) identification method, the driving mechanism for resistome accumulation in receiving environment is unclear. Here, we took advantage of the enhanced ARBs recognition by nanopore long reads to distinguish the indigenous ARBs and the accumulation of WWTP-borne ARBs in the receiving water body of a domestic WWTP. A bioinformatic framework (named ARGpore2: https://github.com/sustc-xylab/ARGpore2) was constructed and evaluate to facilitate antibiotic resistance genes (ARGs) and ARBs identification in nanopore reads. ARGs identification by ARGpore2 showed comparable precision and recall to that of the commonly adopt BLASTP-based method, whereas the spectrum of ARBs doubled that of the assembled Illumina dataset. Totally, we identified 33 ARBs genera carrying 65 ARG subtypes in the receiving seawater, whose concentration was in general 10 times higher than clean seawater's. Notably we report a primary resistome intrusion caused by the revival of residual microbes survived from disinfection treatment. These WWTP-borne ARBs, including several animal/human enteric pathogens, contributed up to 85% of the receiving water resistome. Plasmids and class 1 integrons were reckoned as major vehicles facilitating the persistence and dissemination of ARGs. Moreover, our work demonstrated the importance of extensive carrier identification in determining the driving force of multifactor coupled resistome booming in complicated environmental conditions, thereby paving the way for establishing priority for effective ARGs mitigation strategies.