Identifying Health Effects of Exposure to Trichloroacetamide Using Transcriptomics and Metabonomics in Mice (Mus musculus)

Microarray-based transcriptomics and one-dimensional proton nuclear magnetic resonance (¹H NMR) based metabonomics approaches were employed to investigate the health effects of nitrogenous disinfection byproducts (N-DBPs) of trichloroacetamide (TCAcAm) on mice. Mice were exposed to TCAcAm at concentrations of 50, 500, and 5000 μg/L for 90 days, and hepatic transcriptome and serum metabonome and histopathological parameters were detected in comparison with those of control. TCAcAm esposures resulted in liver inflammation, weight loss (in 5000 ug/L TCAcAm group), and alterations in hepatic transcriptome and serum metabonome. Based on the differentially expressed genes and altered metabolites, several significant pathways were identified, which are associated with lipid, xenobiotics, amino acid and energy metabolism, and cell process. Moreover, integrative pathway analyses revealed that TCAcAm exposure in this study induced hepatotoxicity and cytotoxicity. These results also highlight the noninvasive prospect of transcriptomic and metabonomic approaches in evaluating the health risk of emerging N-DBPs

Metagenomic and Metabolomic Analysis of the Toxic Effects of Trichloroacetamide-Induced Gut Microbiome and Urine Metabolome Perturbations in Mice

Disinfection byproducts (DBPs) in drinking water have been linked to various diseases, including colon, colorectal, rectal, and bladder cancer. Trichloroacetamide (TCAcAm) is an emerging nitrogenous DBP, and our previous study found that TCAcAm could induce some changes associated with host–gut microbiota co-metabolism. In this study, we used an integrated approach combining metagenomics, based on high-throughput sequencing, and metabolomics, based on nuclear magnetic resonance (NMR), to evaluate the toxic effects of TCAcAm exposure on the gut microbiome and urine metabolome. High-throughput sequencing revealed that the gut microbiome’s composition and function were significantly altered after TCAcAm exposure for 90 days in Mus musculus mice. In addition, metabolomic analysis showed that a number of gut microbiota-related metabolites were dramatically perturbed in the urine of the mice. These results may provide novel insight into evaluating the health risk of environmental pollutants as well as revealing the potential mechanism of TCAcAm’s toxic effects

Removal of Steroid Estrogens and Total Nitrogen by Denitrification Biofilter with UV/Peracetic Acid Pretreatment: Performance, Microbial Characteristics, and Mechanism

Total nitrogen (TN) and steroid estrogens (SEs) in secondary effluent challenge widely used denitrification biofilter (DNBF) in achieving the regulated limit value in water reuse, as well as toxicity reduction. Herein, we first use UV/peracetic acid (PAA) as a pretreatment of DNBF for advanced wastewater treatment, followed by an evaluation of its effectiveness in removing TN and SEs from low C/N wastewater. The results showed that UV/PAA-biofilter significantly improved the removal of TN and SEs compared to conventional DNBF. Under the conditions of [PAA]0 = 15 mg/L, UV = 1250 μW/cm2, photoreaction time of 30 min, and biofilter hydraulic retention time (HRT) = 3 h, the SE removal rates could reach more than 95% and the effluent TN maintained less than 10 mg/L. Furthermore, UV/PAA-biofilter improved the reduction of estrogenic activity but not of acute toxicity. Increased extracellular polymeric substance (EPS) content and relative abundance of napA gene were observed in DNBF pretreated with UV/PAA, and Azospira was identified as the core microorganism for denitrogenation. Our investigations confirmed the feasibility of the UV/PAA-biofilter to remove SEs and TN simultaneously, highlighting the great potential of its application in the advanced purification of secondary effluent for safe wastewater reuse

Highly Sensitive and Selective Detection of Inorganic Phosphates in the Water Environment by Biosensors Based on Bioluminescence Resonance Energy Transfer

The accurate detection of phosphate in water is very important to prevent water eutrophication and ensure the health of water quality. However, traditional phosphomolybdenum blue spectrophotometry is not sensitive, is time-consuming, and demands large amounts of chemical reagents. Therefore, highly sensitive, rapid, and environmentally friendly Pi detection methods are urgently needed. Here, we developed a bioluminescence resonance energy transfer (BRET)-based biosensor, which can detect Pi in water quickly, highly sensitively, and highly selectively. The NanoLuc and the Venus fluorescent protein were selected as the bioluminescence donor and energy acceptor, respectively. The best-performing BRET sensor variant, VenusΔC10-PΔC12-ΔN4Nluc, was identified by Pi-specific binding protein (PiBP) screening and systematic truncation. Single-factor experiments optimized the key parameters affecting the detection performance of the sensor. Under the optimal detection conditions, the detection limit of this method was 1.3 μg·L–1, the detection range was 3.3–434 μg·L–1, and it had excellent selectivity, repeatability, and stability. This low-cost and environment-friendly BRET sensor showed a good application prospect in real water quality detection

Additional file 1 of Machine learning-aided analyses of thousands of draft genomes reveal specific features of activated sludge processes

Additional file 1: Table S1. Information about the WWTPs and activate sludge samples analyzed in this study. Table S2. Accession numbers of the metagenomic datasets used in this study. Table S3. Abundance of AS MAGs assigned to each phylum. Table S4. Prediction report of the random forest model. Table S5. Importance values and descriptions of the top 20 COGs identified by random forest model to differentiate the AS and non-AS MAGs. Figure S1. Geographical locations of the WWTPs where activated sludge samples were collected by us and other researchers. Figure S2. Associations between MAG completeness and number of contigs (a), and associations between MAG completeness and number of contigs (b). Figure S3. Venn diagram showing the shared and unique MAGs of WWTP1, WWTP2, WWTP3 and WWTP4. Figure S4. Profile of protein sequences identity between different WWTPs. The protein sequences predicted from all assembly contigs of each WWTP were compared each other with Diamond and then the best hits of the protein sequences were counted and summarized. Figure S5. Random forest parameter tuning and optimization. (a) Number of trees (n_estimators); (b) Tree depth; (c) Maximum features. Figure S6. Phylogeny of the erroneously predicted MAGs. The topology of this tree is exactly same with Fig. 1b. Extended lines were added to show positions of the erroneously predicted MAGs

Correlations of Gut Microbial Community Shift with Hepatic Damage and Growth Inhibition of <i>Carassius auratus</i> Induced by Pentachlorophenol Exposure

Goldfish (<i>Carassius auratus</i>) were exposed to 0–100 μg/L pentachlorophenol (PCP) for 28 days to investigate the correlations of fish gut microbial community shift with the induced toxicological effects. PCP exposure caused accumulation of PCP in the fish intestinal tract in a time- and dose-dependent manner, while hepatic PCP reached the maximal level after a 21 day exposure. Under the relatively higher PCP stress, the fish body weight and liver weight were reduced and hepatic CAT and SOD activities were inhibited, demonstrating negative correlations with the PCP levels in liver and gut content (<i>R</i> < −0.5 and <i>P</i> < 0.05 each). Pyrosequencing of the 16S rRNA gene indicated that PCP exposure increased the abundance of Bacteroidetes in the fish gut. Within the Bacteroidetes phylum, the <i>Bacteroides</i> genus had the highest abundance, which was significantly correlated with PCP exposure dosage and duration (<i>R</i> > 0.5 and <i>P</i> < 0.05 each). Bioinformatic analysis revealed that <i>Bacteroides</i> showed quantitatively negative correlations with <i>Chryseobacterium</i>, <i>Microbacterium</i>, <i>Arthrobacter</i>, and <i>Legionella</i> in the fish gut, and the Bacteroidetes abundance, <i>Bacteroides</i> abundance, and Firmicutes/Bacteroidetes ratio played crucial roles in the reduction of body weight and liver weight under PCP stress. The results may extend our knowledge regarding the roles of gut microbiota in ecotoxicology

2‑Hydroxy-1,4-Naphthoquinone: A Promising Redox Mediator for Minimizing Dissolved Organic Nitrogen and Eutrophication Effects of Wastewater Effluent

Researchers and engineers are committed to finding effective approaches to reduce dissolved organic nitrogen (DON) to meet more stringent effluent total nitrogen limits and minimize effluent eutrophication potential. Here, we provided a promising approach by adding specific doses of 2-hydroxy-1,4-naphthoquinone (HNQ) to postdenitrification bioreactors. This approach of adding a small dosage of 0.03–0.1 mM HNQ effectively reduced the concentrations of DON in the effluent (ANOVA, p < 0.05) by up to 63% reduction of effluent DON with a dosing of 0.1 mM HNQ when compared to the control bioreactors. Notably, an algal bioassay indicated that DON played a dominant role in stimulating phytoplankton growth, thus effluent eutrophication potential in bioreactors using 0.1 mM HNQ dramatically decreased compared to that in control bioreactors. The microbe-DON correlation analysis showed that HNQ dosing modified the microbial community composition to both weaken the production and promote the uptake of labile DON, thus minimizing the effluent DON concentration. The toxic assessment demonstrated the ecological safety of the effluent from the bioreactors using the strategy of HNQ addition. Overall, HNQ is a promising redox mediator to reduce the effluent DON concentration with the purpose of meeting low effluent total nitrogen levels and remarkably minimizing effluent eutrophication effects

Additional file 1 of Machine learning-aided analyses of thousands of draft genomes reveal specific features of activated sludge processes

Additional file 1: Table S1. Information about the WWTPs and activate sludge samples analyzed in this study. Table S2. Accession numbers of the metagenomic datasets used in this study. Table S3. Abundance of AS MAGs assigned to each phylum. Table S4. Prediction report of the random forest model. Table S5. Importance values and descriptions of the top 20 COGs identified by random forest model to differentiate the AS and non-AS MAGs. Figure S1. Geographical locations of the WWTPs where activated sludge samples were collected by us and other researchers. Figure S2. Associations between MAG completeness and number of contigs (a), and associations between MAG completeness and number of contigs (b). Figure S3. Venn diagram showing the shared and unique MAGs of WWTP1, WWTP2, WWTP3 and WWTP4. Figure S4. Profile of protein sequences identity between different WWTPs. The protein sequences predicted from all assembly contigs of each WWTP were compared each other with Diamond and then the best hits of the protein sequences were counted and summarized. Figure S5. Random forest parameter tuning and optimization. (a) Number of trees (n_estimators); (b) Tree depth; (c) Maximum features. Figure S6. Phylogeny of the erroneously predicted MAGs. The topology of this tree is exactly same with Fig. 1b. Extended lines were added to show positions of the erroneously predicted MAGs

Determination of Phosphite in a Eutrophic Freshwater Lake by Suppressed Conductivity Ion Chromatography

The establishment of a sensitive and specific method for the detection of reduced phosphorus (P) is crucial for understanding P cycle. This paper presents the quantitative evidence of phosphite (P, +3) from the freshwater matrix correspondent to the typically eutrophic Lake Taihu in China. By ion chromatography coupled with gradient elution procedure, efficient separation of micromolar levels of phosphite is possible in the presence of millimolar levels of interfering ions, such as chloride, sulfate, and hydrogen carbonate in freshwater lakes. Optimal suppressed ion chromatography conditions include the use of 500 μL injection volumes and an AS11 HC analytical column heated to 30 °C. The method detection limit of 0.002 μM for phosphite was successfully applied for phosphite determination in natural water samples with recoveries ranging from 90.7 ± 3.2% to 108 ± 1.5%. Phosphite in the freshwater matrix was also verified using a two-dimensional capillary ion chromatography and ion chromatography coupled with mass spectrometry. Results confirmed the presence of phosphite in Lake Taihu ranging from 0.01 ± 0.01 to 0.17 ± 0.01 μM, which correlated to 1–10% of the phosphate. Phosphite is an important component of P and may influence biogeochemical P cycle in lakes

Effect of Solids Retention Time on Effluent Dissolved Organic Nitrogen in the Activated Sludge Process: Studies on Bioavailability, Fluorescent Components, and Molecular Characteristics

Wastewater-derived dissolved organic nitrogen (DON) should be minimized by municipal wastewater treatment plants (MWWTPs) to reduce its potential impact on receiving waters. Solids retention time (SRT) is a key control parameter for the activated sludge (AS) process; however, knowledge of its impact on effluent DON is limited. This study investigated the effect of SRT on the bioavailability, fluorescent components, and molecular characteristics of effluent DON in the AS process. Four lab-scale AS reactors were operated in parallel at different SRTs (5, 13, 26, and 40 days) for treatment of primary treated wastewater collected from an MWWTP. Results showed the positive effect of prolonged SRT on DON removal. AS reactors during longer SRTs, however, cannot sequester the bioavailable DON (ABDON) and occasionally contribute to greater amounts of ABDON in the effluents. Consequently, effluent DON bioavailability increased with SRT (R2 = 0.619, p < 0.05, ANOVA). Analysis of effluent DON fluorescent components and molecular characteristics indicated that the high effluent DON bioavailability observed at long SRTs is contributed by the production of microbially derived nitrogenous organics. The results presented herein indicate that operating an AS process with a longer SRT cannot control the DON forms that readily stimulate algal growth