Isolation of Biofilm-Forming Bacteria from Food Processing Equipment Surfaces and the Biofilm-Degrading Activity of Bacillus licheniformis YJE5

Abstract

Food processing environments are prone to microbial contamination, where biofilm formation by persistent bacteria reduces hygiene and food safety. In this study, 27 biofilm-forming bacterial strains were isolated from processing equipment surfaces, with the dominant strains identified as B. cereus LE3, B. cereus YJBR3, and P. cibi F25. An environmental isolate, B. licheniformis YJE5, exhibited no hemolytic activity and demonstrated strong enzymatic potential. Intracellular substances (ICS) extracted from B. licheniformis YJE5, isolated from a food processing environment, significantly inhibited biofilm formation by B. cereus LE3, B. cereus YJBR3, and P. cibi F25 by 47-53% and degraded pre-formed biofilms by 37-44%. Light and confocal laser scanning microscopy confirmed pronounced structural degradation of biofilms following ICS treatment. API ZYM analysis further revealed multiple hydrolytic enzymes, indicating that enzymatic hydrolysis is central to biofilm degradation. Whole-genome sequencing showed a 4.3 Mbp chromosome with diverse metabolic pathways but no antibiotic resistance and virulence genes, confirming the strain's safety. These findings suggest that B. licheniformis YJE5 represents a safe and eco-friendly candidate for controlling biofilm-associated contamination in food processing facilities.