复原乳中耐热菌生物被膜播散规律

Dispersal Law of the Biofilm of Thermoduric Bacteria in Reconstituted Milk

以湿法工艺生产奶粉为理论基础,设计并构建了生物被膜形成装置,研究复原乳中耐热菌生物被膜中的微生物在不同温度、奶液浓度和金属离子等条件下的播散规律,并对成熟生物被膜进行扫描电镜观察。结果表明,奶液中耐热菌在不锈钢管道内壁形成生物被膜,并从成熟生物被膜播散至奶液,成为生产过程污染源;在55℃条件下,4.5 h是生物被膜播散关键点,4.5 h后播散速率快速增加;65℃条件下有利于形成芽孢,然而不能有效抑制生物被膜的形成;高浓度奶液可抑制生物被膜的形成;金属离子对微生物繁殖和生物被膜播散具有促进作用,而对生物被膜形成并无显著影响。分析认为生物被膜特殊的三维结构提供膜内微生物稳定生长、繁殖的环境,保护微生物抵抗流体剪切力等胁迫环境。

This paper is based on the theory of milk powder production with wet procession.The biofilm continuous flow laboratory reactor was designed and constructed in laboratorial scale to study the biofilm formation and microbial changes of thermoduric bacteria in reconstituted milk in different conditions,for instance,temperature,concentration of milk and metal ions,etc.Meanwhile,the biofilm was observed by scanning electron microscopy.The results suggest that thermoduric bacteria in reconstituted milk will form biofilm on the stainless steel pipe inner wall and spread from the mature biofilm to the milk that to be a source of pollution in the production process.In addition,there is a turning point at 4.5h during biofilm detaching in the condition of 55℃.On the other hand,it will be devoted to the formation of spores rather than effectively inhibit the formation of biofilm in the condition of 65℃.High extremely concentration of milk is not conducive to the formation of biofilm.Metal ions will be facilitated to the growth of microorganisms and biofilm spreading not yet to the effect in biofilm formation.It is concluded that biofilm will form the special three-dimensional structure which will be benefit to the microbial growth and resist to the fluid shear or other pressure in a stable environment.