营养琼脂培养基在50 ℃条件下保温18 h后,会出现浑浊现象,给无菌判定带来困难,同时也会影响菌落计数等微生物实验的准确性.为查明营养琼脂培养基在保温后出现浑浊现象的原因,以提高涉及该培养基的所有实验的准确性,文章通过复融法、磷酸盐沉淀法和初始菌控制法对其原因进行研究分析.实验结果表明,导致营养琼脂培养基在保温过程中出现浑浊现象的主要原因是培养基中初始菌含量过高,在121℃灭菌15 min的条件下无法全部灭活.针对验收过程中出现的保温浑浊问题,可以采用辐照灭菌的方法,将培养基以15～18 kgy的剂量进行辐照灭菌,降低初始菌含量,并在121 ℃的条件下灭菌15 min.
Research on the Turbidity Problem and Countermeasures after Insulation of Nutrient Agar Culture Medium
After incubating the nutrient agar medium at 50℃ for 18 hours,the medium became turbid,which made it difficult to determine sterility and also affected the accuracy of microbial experiments such as colony counting.In order to identify the cause of turbidity in nutrient agar culture medium after insulation and improve the accuracy of experiments involving nutrient agar culture medium,this experiment conducted the research and analysis through the thawing method,phosphate precipitation method,and initial bacterial control method.The results show that the main reason for the turbidity of nutrient agar culture medium during the insulation process is the high initial bacterial content in the culture medium,which cannot be completely inactivated under the condition of sterilization at 121 ℃ for 15 minutes.In order to solve the insulation turbidity issue during the acceptance process,the culture medium can be sterilized by irradiation with a dose of 15-18kgy to reduce the initial bacterial content,and then the culture medium can be sterilized at 121 ℃ for 15 minutes.
nutrient agarthawing methodphosphate precipitation methodinitial bacterial control methodinsulationturbidity
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