Study On Biofilm Of Staphylococcus Aureus In Food Processing Equipment

Microbial Varieties of biofilm in food processing equipment were determined in this research. Main microbe in biofilm was was identified by PCR-SSCP and combined with bacteria16SrRNA Sequence, it was proved to be Staphylococcus aureus. The effects of culture conditions on biofilm were inspected. The inhibitory of the commonly used food additives on biofilm was studied, and the results of cleaned by hydrogen peroxide was inspected, too. The paper provided theoretical basis for further study on the control of Staphylococcus aureus biofilm contamination in food processing equipment.The main results were as follows:1. The results after analysised by16SrRNA sequence characteristics showed that the strain with largest population in biofilm was99%homologous with mode strain, and was determined as Staphylococcus aureus. After detected by silver staining and crystal violet staining, it was showed that the total colony of Staphylococcus aureus biofilm was increased and the color deepened gradually with prolonged incubation period,and biofilm amount was the most.2. The results showed that colony exbihited an exponential growth trend after cultured0-2h while Biofilm prepared by stainless steel sheet. It indicated that the stage was attachment phrase and fast growth phrase which staphylococcus aureus attached on stainless steel sheet. Biofilm formation phrase was followed when culutred12-24h, colony was increased with culture period increasing. The count kept constant after24h.3. The results showed that residual glucose, lactose, maltose, fructose, and sucrose with lower concentration were able to promote the formation of BF. The concentration of glucose (2mg/ml) had the greatest improving role during formation of BF. Temperature, pH, concentration of initial suspension had different degrees of influence on the formation of BF, and interaction effects among them could infulence biofilm formation.4. The inhibitory effect of commonly used food additives on biofilm was studied too. Citric acid was shown to have significant inhibitory effect and could inhibit or kill microbial growth at0.06%. Citric acid could inhibit not only biofilm formation, but also the growth of staphylococcus aureus at the0.12%concentration. When citric acid and other three food additives mixed as the ratio of1:1, respectively, inhibitory effect was much better than citric acid used only.5. Compared the effect of removal staphylococcus aureus biofilm at the same concentration of H2O2, sodium hypochlorite and chlorine dioxide. The best removal effect was obtained by H2O2.6. Effect on scavenging staphylococcus aureus suspension by H2O2was studied. The results showed that when no added medium, in the amount of adding H2O2was0.08%and0.1%for15min and10min, respectively, the sterilization rate reached100%. The sterilization rate of bacteria suspension was100%while BF, H2O20.08%for35min and20min.7. Effect on scavenging biofilm by H2O2was studied. The results showed that the sterilization rate was100%when H2O2was0.08%for20min, and H2O2was0.1%as containing0.1(W/V) TSB. Because existing a certain concentration of culture medium, H2O2concentration should be improved6times in order to achieve the same sterilizing effect.