Purpose: The objective of this study was to evaluate enzymes for the reduction of biofilms and to characterize modes of formation in B. cereus biofilms.
Methods: The biofilms of two B. cereusstrains, ATCC 10987 (BC87; reference strain) and a strain isolated from tatsoi green leaf (BC4), were screened for sensitivities to DNaseⅠ, two proteases, and three polysaccharidases using a crystal violet assay. Then, the compositions of extracellular DNA (eDNA), proteins, and carbohydrates in extracellular polymeric substances (EPS) were compared.
Results: In BC87, the biofilm formation was significantly inhibited in the presence of DNase I or cellulose (P<0.05) and no enzyme was able to degrade the preformed biofilms. In BC4, however, the biofilm formation was significantly inhibited by the presence of all the enzymes tested (P<0.05), and those enzymes degrade the preformed biofilms, except for amyloglucosidase. In the analysis of EPS, eDNA content of BC4 was 5-fold higher (29.5 μg) than BC87 (5.7 μg), total protein content of BC4 was 7-fold higher (147.0 μg) than BC87 (20.2 μg), and total carbohydrate contents were similar between BC4 (548.7 μg) and BC87 (425.8 μg).
Significance: Our results give insight into B. cereus biofilm formation and maintenance and indicate that enzyme treatment can be used as a strategy to control biofilms of B. cereus.