Biofilm formation of Bacillus cereus under food-processing-related conditions

Abstract

This study aims to understand the biofilm formation abilities of eight Bacillus cereus strains under food-industry-related conditions. Biofilms were grown in microtiter plates in tryptic soy broth (TSB) or brain heart infusion (BHI) at 30 °C for 24 or 48 h and quantified via the crystal violet assay. A significantly larger of biofilm was formed in TSB than in BHI after 48 h. Selected strains were used to test biofilm formation under food-related conditions produced by different surfaces (e.g., stainless steel, plastic, or glass), temperatures (25 or 30 °C), carbon sources, (glucose or glycerol) and NaCl. Biofilm formation appeared to be affected by surface properties, temperature, and carbon sources. A larger biofilm was formed on stainless steel at 30 °C compared to plastic and glass surfaces at 25 and 30 °C. Moreover, addition of glucose in combination with NaCl in TSB produced significantly larger biofilm than glucose, glycerol and/or NaCl. These results indicate that food-industry-related conditions could promote B. cereus biofilm formation, which is relevant to food safety.