Effects of stress factors on the formation of Bacillus cereus biofilm on glass surfaces

Biofilms formed by foodborne pathogenic bacteria Bacillus cereus was used as material, the effect of food processing temperature stress, p H stress, nutritional stress, osmotic stress and preservatives stress on the formation of Bacillus cereus biofilms were investigated, and the formation of the biofilms were measured by ultrasonic plate method and observed crystal violet staining.The results showed that under the temperature stress, the Bacillus cereus biofilm formed at 4 ℃ and 50 ℃, the formation of biofilms were increased then decreased with increasing temperature, Bacillus cereus formed stable biofilms at30 ℃. Under the p H stress, when the p H was less or more than 7.0, the formation of biofims were significantly reduced, Bacillus cereus formed stable biofilms at p H7.0. Under the stress of nutrition, the abilities of biofilms formation would be improved by adding proper glucose in culture medium and the 4% glucose had obvious effect on promoting the formation of Bacillus cereus biofilms.Under the osmotic stress, low concentration of sodium chloride promoted the formation of Bacillus cereus biofilms, high concentration of sodium chloride could inhibit the formation of Bacillus cereus biofilms and the 0.5% sodium chloride had obvious effect on promoting the formation of Bacillus cereus biofilms.Under preservative stress, the Bacillus cereus biofims of adding 0.15% food preservative were higher than 0.10%. In the food processing, it would not neglect controling bacteria biofilms just only adding food preservatives.