Tetracycline Resistance Genes and Tetracycline Resistant Lactose-Fermenting <i>Enterobacteriaceae</i> in Activated Sludge of Sewage Treatment Plants

Activated sludges were sampled from five sewage treatment plants (STPs) distributed in three geographically isolated areas, i.e., Hong Kong (Shatin, Stanley), Shanghai (Minhang) in China, and the bay area in California (Palo Alto and San Jose) of the United States. Among the tested 14 tetracycline resistance (tet) genes, nine genes encompassing efflux pumps (tetA, tetC, tetE, and tetG), ribosomal protection proteins (tetM, tetO, tetQ, and tetS), and enzymatic modification (tetX) were commonly detected in the STP sludge samples, whereas five genes encompassing efflux pumps [tetB, tetD, tetL, tetK, and tetA(P)] were not detected in any sludge sample. Additionally, 109 lactose-fermenting Enterobacteriaceae (LFE) strains were isolated from the activated sludge of the Shatin STP. Tetracycline-resistant (TR) LFE accounted for 32% of the total 109 LFE strains. The occurrence frequencies of tet genes among all TR-LEF strains varied from 0 to 91%, i.e., tetC (91%), tetA (46%), tetE (9%), tetG (6%), and tetD (6%). Finally, quantitative real-time polymerase chain reaction was used to quantify the change of tetC and tetA genes as the indicator of TR-LEF in the Shatin and Stanley STPs. The results showed that the concentrations of tetC and tetA genes in STP effluent ranged from 104 to 105 copies/mL, significantly lower than those in the influent by 3 orders of magnitude

Evaluating the Transcriptomic and Metabolic Profile of Mice Exposed to Source Drinking Water

Transcriptomic and metabonomic methods were used to investigate mice’s responses to drinking source water (DSW) exposure. After mice were fed with DSW for 90 days, hepatic transcriptome was characterized by microarray and serum metabonome were determined by ¹H nuclear magnetic resonance (NMR) spectroscopy. A total of 243 differentially expressed genes (DEGs) were identified, among which 141 genes were up-regulated and 102 genes were down-regulated. Metabonomics revealed significant changes in concentrations of creatine, pyruvate, glutamine, lysine, choline, acetate, lipids, taurine, and trimethylamine oxide. Four biological pathways were identified by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis where both gene expression and metabolite concentrations were altered in response to DSW exposure. These results highlight the significance of combined use of transcriptomic and metabonomic approaches in evaluating potential health risk induced by DSW contaminated with various hazardous materials

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

Phylogenetic classification and differences in the cecal microbiota of broiler chickens fed a basal diet supplemented with or without 40 (LYS40), 100 (LYS100), or 200 ppm (LYS200) lysozyme or 400 ppm flavomycin.

Phylum compositions of the bacterial (A) and fungal (B) communities in the cecal microbiota characterized based on sequencing of 16S rRNA amplicons (V3-V4 region) and ITS fragment sequencing.</p

Enrichment of Gene Ontology (GO) functions in the cecal microbiota of broiler chickens fed a basal diet supplemented with 40 (LYS40), 100 (LYS100), or 200 ppm (LYS200) lysozyme or 400 ppm flavomycin determined by comparison with the GO functions observed in the cecal microbiota of broiler chickens fed only the basal diet (control).

Enrichment of Gene Ontology (GO) functions in the cecal microbiota of broiler chickens fed a basal diet supplemented with 40 (LYS40), 100 (LYS100), or 200 ppm (LYS200) lysozyme or 400 ppm flavomycin determined by comparison with the GO functions observed in the cecal microbiota of broiler chickens fed only the basal diet (control).</p

Enrichment of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in the cecal microbiota of broiler chickens fed a basal diet supplemented with 40 (LYS40), 100 (LYS100), or 200 ppm (LYS200) lysozyme or 400 ppm flavomycin determined by comparison with the KEGG functions observed in the cecal microbiota of broiler chickens fed only the basal diet (control).

Enrichment of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in the cecal microbiota of broiler chickens fed a basal diet supplemented with 40 (LYS40), 100 (LYS100), or 200 ppm (LYS200) lysozyme or 400 ppm flavomycin determined by comparison with the KEGG functions observed in the cecal microbiota of broiler chickens fed only the basal diet (control).</p

Biodiversity indices of the gut microbiota in broiler chickens fed a basal diet supplemented with 0 (control), 40 (LYS40), 100 (LYS100), or 200 ppm (LYS200) lysozyme or 400 ppm flavomycin.

Biodiversity indices of the gut microbiota in broiler chickens fed a basal diet supplemented with 0 (control), 40 (LYS40), 100 (LYS100), or 200 ppm (LYS200) lysozyme or 400 ppm flavomycin.</p

Effects of dietary supplementation with lysozyme and flavomycin on the composition and distribution of bacterial and fungal OTUs in the cecal microbiota of broiler chickens.

(A&B) Venn diagrams showing the occurrence of bacterial (A) and fungal (B) OTUs identified in 16S rRNA and ITS fragment sequencing of cecal microbiota of chickens fed a basal diet supplemented with or without 40 (LYS40), 100 (LYS100), or 200 ppm (LYS200) lysozyme or 400 ppm flavomycin. (C&D) Grouping of cecal bacterial (C) and fungal (D) communities based on principle component analyses of Illumina sequencing of 16S rRNA amplicons (V3-V4 region) and ITS fragment sequencing, respectively.</p

Effects of dietary supplementation with lysozyme on the structure and function of the cecal microbiota in broiler chickens - Fig 3

Clustering analysis of the compositions of the abundant (>1%) bacterial genera (A) and fungal orders (B) in the cecum of chickens fed a basal diet plus 0 (control), 40 (LYS40), 100 (LYS100), or 200 ppm (LYS200) lysozyme or 400 ppm flavomycin. Values in individual squares represent relative percentage abundances of individual genera or orders. Unc represents unclassified.</p

Expression and classification of carbohydrate-active enzymes in the cecal microbiota of broilers fed a corn-based diet supplemented with 0 (control), 40 (LYS40), 100 (LYS100), or 200ppm (LYS200) lysozyme or 400 ppm flavomycin.

(A) Expression of carbohydrate-active enzyme genes in the cecal microbiota of broilers with different dietary treatments. (B) Taxonomy and relative abundances of the classifiable carbohydrate-active enzyme genes identified in cecal microbiota of broilers with different dietary treatments.</p