The Relationship between Reactive Oxygen Species and Bacillus cereus Biofilms Formation

Abstract

In order to clarify the correlation between reactive oxygen species (ROS) and Bacillus cereus biofilms, the ROS mediated by NADPH oxidase in the Bacillus cereus that were isolated from commercially available raw milk was used as the main target. The relationship between the formation of Bacillus cereus biofilms and ROS were analyzed by using supplement hydrogen peroxide (H2O2) as exogenous reactive oxygen species (ROS), N-acetylcysteine (NAC) as ROS scavenging agent and diphenyl iodide chloride (DPI) as NADPH oxidase inhibitor. The results showed that the treatment groups of 0.01 μmol/L H2O2, 1 μmol/L H2O2 and 100 μmol/L H2O2 average biofilms were higher than the control group average biofilms (P0.05). With the increase of H2O2 concentration, ROS gradually decreased. The treatment groups of NAC average biofilms were higher than the control group average biofilms (P5 μmol/L, with the increase of DPI concentration, the average biofilms were lower than the control group average biofilms (P<0.05), and the ROS increased. The results showed that without affecting the growth and activity of Bacillus cereus, the reduction of ROS induced by certain concentration of H2O2, NAC and DPI enhanced the Bacillus cereus biofilms. Confocal laser scanning microscopy showed stronger staining and red network structures in the treated groups compared to the control groups, while the untreated groups showed loose structures and fewer biofilms, suggesting that ROS inhibits the formation of Bacillus cereus biofilms.

Keywords

• bacillus cereus
• reactive oxygen species (ros)
• hydrogen peroxide (h2o2)
• n-acetylcysteine (nac)
• diphenyliodide chloride (dpi)
• biofilm