金黄色葡萄球菌与烟曲霉生长最低水分活度的研究

Study on the Minimum Water Activity Required for Growth of Staphylococcus Aureus and Aspergillus Fumigatus

目的探讨使用葡萄糖、甘油、氯化钠3种介质调节不同水分活度的生长环境对金黄色葡萄球菌及烟曲霉生长的影响。方法分别加入3种不同的介质控制胰酪大豆胨液体(TSB)培养基、沙氏葡萄糖琼脂(SDA)培养基的水分活度,通过定时对金黄色葡萄球菌进行平板计数、烟曲霉的菌落生长直径测量,判定微生物生长的最低水分活度。结果金黄色葡萄球菌在甘油与氯化钠调节的水分活度环境下,菌落数均呈下降趋势;在蔗糖介质调节水分活度为0.85,0.86时,菌落数在初始值上下波动,基本维持不变;调节水分活度为0.87时,菌落数在略减后迅速增加。烟曲霉在3种介质调节的所有水分活度环境下,均处于生长停滞状态。结论环境水分活度的高低对金黄色葡萄球菌、烟曲霉的生长有一定影响。金黄色葡萄球菌在蔗糖介质中的生长最低水分活度近似为0.86,烟曲霉生长最低水分活度>0.83。金黄色葡萄球菌在甘油与氯化钠基质,烟曲霉在3种基质中的最低水分活度与美国药典中收录的最低水分活度值并不相符。

OBJECTIVE To explore the effects on Staphylococcus aureus and Aspergillus fumigatus growth of different water activities by adding glucose glycerol and sodium chloride.METHODS Three different media were added to control the water activity of TSB medium and SDA medium respectively.The minimum water activity for microbial growth was judged by counting Staphylococcus aureus and measuring the colony growth diameter of Aspergillus fumigatus in successive time.RESULTS The colony number of Staphylococcus aureus decreased under the water activity regulated by glycerol and sodium chloride.When the water activity was adjusted at 0.85 and 0.86 in sucrose medium,the colony number fluctuated up and down at the initial value,and basically remained unchanged.When the water activity was adjusted at 0.87,the colony number increased rapidly after a slight decrease.The growth of Aspergillus fumigatus was stagnant under all water activities regulated by three media.CONCLUSION The level of environmental water activity has a certain impact on the growth of Staphylococcus aureus and Aspergillus fumigatus.The minimum water activity required for the growth of Staphylococcus aureus in sucrose medium is approximately 0.86 and the minimum water activity required for the growth of Aspergillus fumigatus is greater than 0.83.The minimum water activity of Staphylococcus aureus in glycerol and sodium chloride substrates,and Aspergillus fumigatus in the three substrates do not match the minimum water activity values recorded in the US Pharmacopoeia.