Expression of a Shiga-Like Toxin during Plastic Colonization by Two Multidrug-Resistant Bacteria, RIT668 and RIT669, Isolated from Endangered Turtles ().

RIT668 and RIT669 were isolated from endangered spotted turtles (). Whole-genome sequencing, annotation and phylogenetic analyses of the genomes revealed that the closest relative of RIT668 is ATCC 7966 and A60 for RIT669. Resistome analysis showed that and harbor six and 19 different antibiotic resistance genes, respectively. Both bacteria colonize polyethylene and polypropylene, which are common plastics, found in the environment and are used to fabricate medical devices. The expression of six biofilm-related genes-biofilm peroxide resistance protein (), biofilm formation regulatory protein subunit R (), biofilm formation regulatory protein subunit S (), biofilm formation regulator (), toxin-antitoxin biofilm protein (tabA) and transcriptional activator of curli operon ()-and two virulence factors-Vi antigen-related gene () and Shiga-like toxin (-)-was investigated by RT-PCR. displayed a >2-fold increase in expression in cells adhering to both polymers, adhering on polyethylene displayed a >2-fold, and on polypropylene a >6-fold upregulation of . Thus, the two new isolates are potential pathogens owing to their drug resistance, surface colonization and upregulation of a -type diarrheal toxin on polymer surfaces.