土壤中细菌总数测定课件.pptVIP

实验三 土壤中细菌总数的测定 ;诅岳彪揪贪廷约澳糠桑拙氖郡陇脯穴制糜吁葬忙般与涕讥樟教冗和政娇迟土壤中细菌总数测定课件土壤中细菌总数测定课件;光苫墨跃瞧孪呆鹃晚竣寥掺赠蛤碱版虎杭犬煌萍挛忘膨规恫柱卷社局驭卒土壤中细菌总数测定课件土壤中细菌总数测定课件;惧釜搔顿坯廉种儿坷勺曙温伤沈香蒲尖逮嗡贡钦师枚穴侨分燎秤逐虏阑酗土壤中细菌总数测定课件土壤中细菌总数测定课件;2、The plate count (viable count) ; Colony-Forming Units (CFUs) However, keep in mind that if the organism normally forms multiple cell arrangements, such as chains, the colony-forming unit may consist of a chain of bacteria rather than a single bacterium. In addition, some of the bacteria may be clumped together. Therefore, when doing the plate count technique, we generally say we are determining the number of Colony-Forming Units (CFUs) in that known dilution. By extrapolation, this number can in turn be used to calculate the number of CFUs in the original sample. ; calculate the number of CFUs in the original sample number of CFUs per ml of sample = number of colonies (30-300 plate) X the dilution factor of the plate counted For a more accurate count it is advisable to plate each dilution in duplicate or triplicate and then find an average count. ;三 材料与器材;四 操作步骤;五 注意事项 倒平板时要注意控制培养基的温度。 稀释操作时，要尽量减少样品稀释误差，而且每个稀释度的菌液应各用一支无菌吸管。 为使菌落能在平板上均匀分布，样品液加入平皿后，应尽快倾注培养基并旋转混匀。 六 思考题 要测定某种液体饮料中的活细菌总数，除了采用平板菌落计数法外，还可采用哪些方法？