Biofilm formation, cell hydrophobicity, cytotoxic potential, genetic diversity, resistance to antimicrobials, and toxigenic profile properties among Bacillus cereus groups isolated from kitchen sponges in the Republic of Korea

This study aimed to characterize Bacillus cereus isolates recovered from the kitchen sponges used in domestic environments, the Republic of Korea, with a particular focus on analyzing antibiotic susceptibility, biofilm formation, cell surface hydrophobicity (CSH), cytotoxic potential, genetic diversity, and toxigenic profile properties. B. cereus isolates displayed moderate or weak biofilm-forming capabilities, and CSH levels greatly differed among the isolates. Several isolates displayed strong cytotoxic effects despite lacking key toxin-encoding genes. All 26 B. cereus isolates were clustered into eight distinct groups and survived at ClO2, NaClO, ethanol, acetic acid, and lactic acid, while being highly sensitive to H2O2. Additionally, 7 (26.9%) and 11 (42.3%) B. cereus isolates possessed enterotoxin genes and the cereulide-encoding gene ces, respectively. Our findings highlight kitchen sponges as potential reservoirs of disinfectant/sanitizer-tolerant and toxigenic B. cereus strains, underscoring a cross contamination risk in domestic environments, emphasizing the need for optimized hygiene management strategies.