Characterization of silver resistance in two Gram-positive soil bacteria
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Abstract
Identification of genetically linked silver resistance in bacteria has only occurred in Gram-negative medically isolated bacteria through the sil operon. This study was conducted to characterize the silver resistance observed in two Gram-positive bacteria, labelled Paenibacillus sp. SS2 and Lysinibacillus sp. SS4, isolated from silver contaminated soils. Both isolates did not possess the sil operon, as determined by the lack of silE and silR genes. It was determined that both isolates possessed an inducible mechanism for resistance when exposed to silver, that in the case of SS2, is linked to nalidixic acid resistance. Environmental stressors on the organisms (presence/absence of NaCl in media, media concentrations, and temperature changes) revealed that the mechanism of resistance is negatively impacted under non-optimal conditions. This is one of the few studies that looked to bridge the gap in knowledge with regards to silver resistance in Gram-positive bacteria.