探索改变培养基成分和接种方法对细菌总数检测的影响

Influence of culture medium and inoculation methods on detection of the total number of bacteria

目的为了探讨国标法中使用的培养基和接种方法来培养所有样品的细菌总数是否能真实反映样品受微生物污染的情况。方法本实验以饮用水源井为对象，采用涂布法与国标倾注法分别在国标使用营养琼脂、符合该实验对象营养的异养培养基、自养培养基、混合培养基4种不同成分培养基上进行菌落计数实验，应用t检验、方差分析统计方法。结果发现涂布法得到的细菌总数量是倾注法的5倍～10倍（P=0．0020〈0．05），且菌落大而分散便于计数。不论涂布法和倾注法，营养琼脂培养基上培养获得菌落计数最少（P=0．001〈0．05），异养培养基上培养获得最多且涂布法均显示菌落不可计数。48h与96h培养对结果无差别（F=1．288，P=0．870）。结论建议在实际应用中，要根据实际情况采用最适合的接种方法，根据样品的特性探索改变培养基成分，来提高细菌总数检出量。

Objective To explore the accuracy of culture medium and inoculation methods from national standard method in de- tecting the total number of bacteria, which can reflect the microbial contamination situation. Methods The water samples were collected from drinking water source wells to detect the colony count by coating method and national standard pouring method on nutrient agar, heterotrophic culture medium, autotrophic culture medium and mixed culture medium. In addition, t test and ano- va were used for statistical analysis. Results The total number of bacteria by coating method was 5 - 10 times the number of pouting method（ P = 0. 0020, 〈 O. 05 ） , and large scattered colonies was easy for counting. Regardless of coating method and pouting method, nutrient agar medium had the minimum colony counting（ P = 0. 001, 〈 0.05 ） , while heterotrophic culture me- dium had the maximum colony counting, especially coating method showed countless. There was no difference in the cuhurre re- suits between 48 hours and 96 hours （ F = 1. 288, P = 0. 870）. Conclusion It was suggested that the optimal inoculation method should be selected in accordance with the practical application, and the culture medium varied based on the properties of the samples to improve the detection limit of total number of bacteria.