细菌在生菜基质中生长的影响因素

Factors for Bacterial Growth in Lettuce

生菜上的初始菌数、培养温度和培养基质类型等因素对细菌的生长具有显著影响,运用甲板菌落计数法,以生菜汁和生菜叶片作为对比基质、大肠杆菌Escherichia coli 1.1187和生菜固有细菌为对象,结合模拟北京地区生菜冷藏供应链波动温度过程,比较分析细菌总数的变化.结果表明,初始菌数越大达到最大菌数时间相对较长,菌数较高.恒温培养下,37℃细菌增殖量大,速度快;模拟供应链温度条件下,前期细菌受到抑制,后期生长加快.灭菌生菜汁相比新鲜生菜汁和生菜叶不利于大肠杆菌E.coli 1.1187的正常生长,而生菜固有细菌与大肠杆菌E.coli 1.1187之间可能存在协同效应,可促进其生长.

In order to explore the effects of initial bacterial counts,cultivation temperature and cultivation matrix on the growth of bacteria,the lettuce juice and lettuce leaves woe used as the matrix to evaluate the number of Escherichia coli 1.1187 and original bacteria by plate colony count method.Meanwhile,the change of total bacteria in lettuce with mimic temperature fluctuation of cold supply chain for lettuce in Beijing area was analyzed.The results indicated that the larger initial bacterial counts resulted in a delayed peak time of maximum bacterial count and larger total bacterial count.At the constant temperature,bacteria at 37℃ revealed the faster growth.Under the mimic temperature of cold supply chain,the bacteria were inhibited at the early stage,and then revealed the accelerated growth at the late stage.Compared with fresh lettuce juice and lettuce leaves,the sterile lettuce juice was not good for the regular growth of E coli 1.1187.However,original bacteria flora might promote the growth of E coli 1.1187.