XXXX Influences Antibiotic Resistance and Alters Anaerobic Digester Microbial Community Structure.

@entity25407 @entity577 @entity844 @entity24055
UNASSIGNED: @entity25407 ( @entity24055 ) is one of the most abundant organic micropollutants detected in biosolids. Lab-scale anaerobic digesters were amended with @entity24055 at concentrations ranging from the background concentration of seed biosolids (30 mg/kg) to toxic concentrations of 850 mg/kg to determine the effect on @entity577 production, relative abundance of antibiotic resistance genes, and microbial community structure. Additionally, the @entity24055 addition rate was varied to determine the impacts of acclimation time. At environmentally relevant @entity24055 concentrations (max detect = 440 mg/kg), digesters maintained function. Digesters receiving 450 mg/kg of @entity24055 maintained function under gradual @entity24055 addition, but volatile @entity844 concentrations increased, pH decreased, and @entity577 production ceased when immediately fed this concentration. The concentrations of the mexB gene (encoding for a multidrug efflux pump) were higher with all concentrations of @entity24055 compared to a control, but higher @entity24055 concentrations did not correlate with increased mexB abundance. The relative abundance of the gene tet(L) was greater in the digesters that no longer produced @entity577 , and no effect on the relative abundance of the class 1 integron integrase encoding gene (intI1) was observed. Illumina sequencing revealed substantial community shifts in digesters that functionally failed from increased levels of @entity24055 . More subtle, yet significant, community shifts were observed in digesters amended with @entity24055 levels that did not inhibit function. This research demonstrates that @entity24055 can select for a multidrug resistance encoding gene in mixed community anaerobic environments, and this selection occurs at concentrations (30 mg/kg) that can be found in full-scale anaerobic digesters (U.S. median concentration = 22 mg/kg, mean = 39 mg/kg).
