[理学]第七章 微生物的生长.ppt

一些细菌的代时 不同温度下的代时 典型的生长曲线 （Growth curve） 一条典型的生长曲线至少可以分为迟缓期、对数期、稳定期和衰亡期等四个生长时期。 营养物浓度与对数期生长速率和产量 作用方式：影响微生物的生长速率和总生长量 生长限制因子：凡是处于较低浓度范围内，可影响生长速率和菌体产量的营养物就称生长限制因子 （二）微生物生长温度类型 ★不同生理生化过程的最适温度 不同微生物的生长pH值范围 生长的最适pH值与发酵的最适pH值 血球计数板是一块特制的载玻片，上面有一计数室，面积是1mm2，高0.1mm，容积是0.1mm3,整个计数室被划分为若干个中格和小格，当稀释的菌悬液被加到计数室后，通过计算方格中的菌数可推算出计数室内的总菌数，从而求出每毫升菌液所含的菌数。 1. A standard plate count (viable count) reflects the number of viable microbes and assumes that each bacterium grows into a single colony; plate counts are reported as number of colony-forming units (CFU) per ml (CFU/ml) or per g (CFU/g) of sample. 最常用的活菌计数法。 将适当稀释的菌液倾注平板或涂布在平板表面，经保温培养后，以平板上出现的菌落数乘以稀释度就可以计算出原菌液的含菌量。 直径9cm的培养皿平板上出现菌落数一般以50~500为宜。按照国家标准规定的样品菌落总数测定的计数原则，以平板菌落数在30~300之间为报告依据。 ★技术要求：样品充分混匀，操作熟练快速（15~20min完成操作），严格无菌操作； 注意事项：每一支吸管只能用于一个稀释度，样品混匀处理，倾注平板时的培养基温度； 适用范围：中温、好氧和兼性厌氧、能在营养琼脂上生长的微生物， 误差：多次稀释造成的误差是主要来源，其次还有由于样品内菌体分布不均匀、以及不当操作 What Is a Colony-Forming Unit? When we are putting bacterial cells in contact with the medium in a petri plate – such as when we inoculate a certain amount of a natural sample into a plate or use a loop to streak a plate from a sample or culture (just to give two of many possible examples) – we expect the microscopic cells to multiply and ultimately form masses of cells visible to the naked eye. These macroscopic masses are called colonies, having been formed by cells which are able to utilize the nutrients in the medium under the conditions in which the plates are incubated. Besides nutrients, we have to consider temperature, oxygen availability, and other factors that are conducive for metabolism. As stated in the introduction to Experiment 1 in the lab manual: When we observe colonies, we cannot assume each arose from just one cell originally planted on the medium, however. A pair, chain or cluster of cells which land on the medium in close proximity to each other can multiply and produce a single colony. Thus, we use the term colony-forming unit when we consider the common origin for