金黄色葡萄球菌(简称金葡菌)污染是危害速冻水饺食品安全的风险因子,生物被膜是食品加工中细菌污染的潜在来源。为研究产品中金葡菌生物被膜形成特性,以及对消毒剂的抗性作用,以从速冻水饺中分离的金葡菌菌株为研究对象,研究了在两种常用材料表面上的生物被膜形成能力、黏附基因的分布、环境条件的影响,比较了3种消毒剂对成熟生物被膜中菌体的杀灭作用。结果表明,与聚苯乙烯表面相比,分离株在不锈钢表面能形成更强的被膜;各分离株均能检出4种以上的被膜形成基因,eno和clfB检出率100%,而bap基因在所有菌株都未被检测到。在不锈钢表面,sasG的检出与被膜形成呈极显著正相关(P<0.01),clfA和fnbA呈显著的正相关(P<0.05),而icaAD、icaBC和fib呈极显著的负相关(P<0.01);在聚苯乙烯表面,sasG呈显著正相关,fib呈显著负相关(P<0.05)。菌体生长最佳温度37 ℃有利于形成更多的生物被膜,在室温25 ℃下,菌株仍能形成较多生物量的被膜。pH 7时菌株形成被膜量最多,弱酸性和弱碱性条件下,菌株受到的影响较小。在低质量分数(<5%)条件下,NaCl对被膜的形成有一定的刺激作用。被膜的形成能在很大程度上提高膜内细胞对消毒剂的抗性,3种消毒剂中,过氧乙酸对生物被膜内菌体杀灭效果最好。该研究的结果为速冻水饺中金葡菌生物被膜研究提供了新的数据,为进一步防治和减少生物被膜的危害奠定了基础。
Staphylococcus aureus contamination is a risk factor for food safety in quick-frozen dumpling products. Biofilms represent a potential source of bacterial contamination in food processing. In order to study biofilm formation characteristics of S. aureus in quick-frozen dumpling products and the resistance to disinfectants, the investigations were carried out using strains isolated from the products. Biofilm forming ability of the isolates were investigated including biofilm formation on the surface of polystyrene (PS) and stainless steel (SS), presence of adhesion genes, effects of environmental conditions, and bactericidal effects of three disinfectants against biofilm cells. The results showed that the isolates formed stronger biofilms on the surface of SS than PS. More than four adhesion genes were detected in each isolate. The presence rate of eno and clfB genes were 100%, whereas bap gene was not detected in any of the isolates. On the surface of SS, the presence of sasG showed highly significant positive correlation with biofilm formation (P<0.01), and clfA and fnbA showed significant positive correlation with biofilm formation respectively (P<0.05), while that of icaAD, icaBC and fib showed highly significant negative correlation (P<0.01). On the surface of PS, the presence of sasG showed a significant positive correlation with biofilm formation (P<0.05), and fib showed a significant negative correlation (P<0.05). The optimal growth temperature of 37 ℃ was favorable for the formation of more biofilms. At room temperature (25 ℃), the strains still formed relatively high biomass of biofilm. The largest amount of biofilm was observed to form at pH 7. Under weak acidic and weak alkaline conditions, the biofilm formation was less affected. At NaCl<5%, a certain stimulating effect was observed on the film formation. The biofilm greatly enhanced the resistance of the cells wrapped inside to the disinfectant tested. Among the three disinfectants tested, peracetic acid was found to be the most effective against biofilms cells. The results provide new data for the study of biofilms formed by S. aureus in quick-frozen dumplings, laying the basis for further prevention and reduction of the harm of the biofilm.
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