Project description:Antibiotic resistance is exacerbated by the exchange of antibiotic resistance genes (ARGs) between microbes from diverse habitats. Plasmids are important ARGs mobile elements and are spread by horizontal gene transfer (HGT). In this study, we demonstrated the presence of multi-resistant plasmids from inhalable particulate matter (PM) and its effect on gene horizontal transfer. Three transferable multi-resistant plasmids were identified from PM in a hospital, using conjugative mating assays and nanopore sequencing. pTAir-3 contained 26 horizontal transfer elements and 10 ARGs. Importantly pTAir-5 harbored carbapenem resistance gene (blaOXA) which shows homology to plasmids from human and pig commensal bacteria, thus indicating that PM is a media for antibiotic resistant plasmid spread. In addition, 125 μg/mL PM2.5 and PM10 significantly increased the conjugative transfer rate by 110% and 30%, respectively, and augmented reactive oxygen species (ROS) levels. Underlying mechanisms were revealed by identifying the upregulated expressional levels of genes related to ROS, SOS, cell membranes, pilus generation, and transposition via genome-wide RNA sequencing. The study highlights the airborne spread of multi-resistant plasmids and the impact of inhalable PM on the horizontal transfer of antibiotic resistance.
Project description:Broad-spectrum antibiotics are frequently prescribed to children. The period of early-childhood represents a time where the developing microbiota may be more sensitive to environmental perturbations, which thus might have long-lasting host consequences. We hypothesized that even a single early-life broad-spectrum antibiotic course at a therapeutic dose (PAT) leads to durable alterations in both the gut microbiota and host immunity. In C57BL/6 mice, a single early-life tylosin (macrolide) course markedly altered the intestinal microbiome, and affected specific intestinal T-cell populations and secretory IgA expression, but PAT-exposed adult dams had minimal immunologic alterations. No immunological effects were detected in PAT-exposed germ-free animals; indicating that microbiota are required for the observed activities. Transfer of PAT-perturbed microbiota led to delayed sIgA expression indicating that the altered microbiota is sufficient to transfer PAT-induced effects. PAT exposure had lasting and transferable effects on microbial community network structure. Together these results indicate the impact of a single therapeutic early-life antibiotic course altering the microbiota and modulating host immune phenotypes that persist long after exposure has ceased.
Project description:Broad-spectrum antibiotics are frequently prescribed to children. The period of early-childhood represents a time where the developing microbiota may be more sensitive to environmental perturbations, which thus might have long-lasting host consequences. We hypothesized that even a single early-life broad-spectrum antibiotic course at a therapeutic dose (PAT) leads to durable alterations in both the gut microbiota and host immunity. In C57BL/6 mice, a single early-life tylosin (macrolide) course markedly altered the intestinal microbiome, and affected specific intestinal T-cell populations and secretory IgA expression, but PAT-exposed adult dams had minimal immunologic alterations. No immunological effects were detected in PAT-exposed germ-free animals; indicating that microbiota are required for the observed activities. Transfer of PAT-perturbed microbiota led to delayed sIgA expression indicating that the altered microbiota is sufficient to transfer PAT-induced effects. PAT exposure had lasting and transferable effects on microbial community network structure. Together these results indicate the impact of a single therapeutic early-life antibiotic course altering the microbiota and modulating host immune phenotypes that persist long after exposure has ceased.
Project description:To understand microbial community functional structures of activated sludge in wastewater treatment plants (WWTPs) and the effects of environmental factors on their structure, 12 activated sludge samples were collected from four WWTPs in Beijing. GeoChip 4.2 was used to determine the microbial functional genes involved in a variety of biogeochemical processes. The results showed that, for each gene category, such as egl, amyA, nir, ppx, dsrA sox and benAB, there were a number of microorganisms shared by all 12 samples, suggestive of the presence of a core microbial community in the activated sludge of four WWTPs. Variance partitioning analyses (VPA) showed that a total of 53% of microbial community variation can be explained by wastewater characteristics (25%) and operational parameters (23%), respectively. This study provided an overall picture of microbial community functional structures of activated sludge in WWTPs and discerned the linkages between microbial communities and environmental variables in WWTPs. Four full-scale wastewater treatment systems located in Beijing were investigated. Triplicate samples were collected in each site.
Project description:Horizontal transfer of plasmids is one of the main drivers of bacterial adaptation, resulting e.g. in the spread of antibiotic resistance. We investigated the marine Roseobacter group and studied how conjugation affects the gene expression and biology of the new host. We showed that the two syntenic 126 kb and 191 kb plasmids of Dinoroseobacter shibae can be conjugated into representatives of all major lineages of Rhodobacteraceae. In the model organism Phaeobacter inhibens their acquisition resulted in differential expression of genes related to motility, transport and the synthesis of vitamins. Moreover, the decrease of the potent antibiotic tropodithietic acid reduced the energetic burden of Phaeobacter and resulted in an enhanced growth. While the T4SS systems of both plasmids were silenced in the new host, the ability to kill the dinoflagellate was exclusively transferred via the 191 kb plasmid from D. shibae to P. inhibens. Our findings showed drastic consequences of plasmid conjugation; genetic reprogramming of the novel host resulted in considerable fitness changes leading to the prediction that horizontal gene transfer triggers bacterial speciation.
Project description:The SARS-CoV-2 virus is continuously evolving, with appearance of new variants characterized by multiple genomic mutations, some of which can affect functional properties, including infectivity, interactions with host immunity, and disease severity. The rapid spread of new SARS-CoV-2 variants has highlighted the urgency to trace the virus evolution, to help limit its diffusion, and to assess effectiveness of containment strategies. We propose here a PCR-based rapid, sensitive and low-cost allelic discrimination assay panel for the identification of SARS-CoV-2 genotypes, useful for detection in different sample types, such as nasopharyngeal swabs and wastewater. The tests carried out demonstrate that this in-house assay, whose results were confirmed by SARS-CoV-2 whole-genome sequencing, can detect variations in up to 10 viral genome positions at once and is specific and highly sensitive for identification of all tested SARS-CoV-2 clades, even in the case of samples very diluted and of poor quality, particularly difficult to analyze.
Project description:Bio-augmentation could be a promising strategy to improve processes for treatment and resource recovery from wastewater. In this study, the Gram-positive bacterium Bacillus subtilis was co-cultured with the microbial communities present in wastewater samples with high concentrations of nitrate or ammonium. Glucose supplementation (1%) was used to boost biomass growth in all wastewater samples. In anaerobic conditions, the indigenous microbial community bio-augmented with B. subtilis was able to rapidly remove nitrate from wastewater. In these conditions, B. subtilis overexpressed nitrogen assimilatory and respiratory genes including NasD, NasE, NarG, NarH, and NarI, which arguably accounted for the observed boost in denitrification. Next, we attempted to use the the ammonium- and nitrate-enriched wastewater samples bio-augmented with B. subtilis in the cathodic compartment of bioelectrochemical systems (BES) operated in anaerobic condition. B. subtilis only had low relative abundance in the microbial community, but bio-augmentation promoted the growth of Clostridium butyricum and C. beijerinckii, which became the dominant species. Both bio-augmentation with B. subtilis and electrical current from the cathode in the BES promoted butyrate production during fermentation of glucose. A concentration of 3.4 g/L butyrate was reached with a combination of cathodic current and bio-augmentation in ammonium-enriched wastewater. With nitrate-enriched wastewater, the BES effectively removed nitrate reaching 3.2 mg/L after 48 h. In addition, 3.9 g/L butyrate was produced. We propose that bio-augmentation of wastewater with B. subtilis in combination with bioelectrochemical processes could both boost denitrification in nitrate-containing wastewater and enable commercial production of butyrate from carbohydrate- containing wastewater, e.g. dairy industry discharges. These results suggest that B. subtilis bio-augmentation in our BES promotes simultaneous wastewater treatment and butyrate production.