Characterization of Brevibacillus biofilm isolated from pasteurized milk and evaluation of the efficacy of sodium hypochlorite, CIP, and enzymatic treatment against the biofilm

Bacterial biofilms pose significant food safety threats to the dairy industry. This study identified Brevibacillus contamination in pasteurized milk at a processing plant, with biofilm formation observed on polyethylene plastic and stainless steel surfaces. The presence of milk promoted robust growth of Brevibacillus, facilitating biofilm formation and spore production. Biofilm structure, nanowires, and potential swelling were visualized on SEM images. Raman spectroscopy analysis revealed enrichment of lipids and amide I in milk-formed biofilms, resulting in a hydrophobic tendency as evidenced by contact angle measurements. Cultivable cell counts in milk-formed biofilms post-treatment with sodium hypochlorite or the alkaline and acid regime were approximately 7 and 3 log CFU/well, respectively. Effective biofilm removal was achieved through enzymatic treatment (lipase and DNase I) followed by an alkaline and acid regime. These findings underscore the pivotal role of biofilms in contaminating milk processing plants and highlight the urgent need for effective biofilm control strategies to safeguard the dairy industry.