屎肠球菌产生有机酸降低琼脂胶凝作用

目的探讨细菌破坏琼脂凝胶形成的原因和机制。方法利用细菌培养技术培养细菌;高压灭菌再融化琼脂-酵母培养基,室温下观察其是否凝固;利用硬度测量仪测量培养基硬度;pH测量仪测量pH值。结果首先,固体琼脂培养基在培养屎肠球菌之后再融化出现室温条件下不凝固现象;其次,pH是一个影响琼脂凝固性的主要因素;最后,屎肠球菌通过发酵产酸而降低pH,当pH值小于4时就破坏了琼脂的凝固性。结论细菌发酵产生酸性物质,降低了培养基pH,引起琼脂凝固点降低。

Enterococcus faecium reduces agar gelatination via generating organic acids

Abstract: Objective To discuss the causes and mechanisms of the destroy of agar gelatinization by bacteria. Methods Bacteria were cultured with bacterial culturing technology; The gelatinization of agar-yeast medium liquefied by using autoclave was observed under room temperature; the rigidity of the medium was measured by using rigidity meter; pH value was assessed by using pH meter. Results First, solid agar medium which had been used to culture Enterococcus faecium did not gelatinize any more after it was liquefied using autoclave; Second, pH was an important factor contributing to agar gelatinization; Finally, Enterococcus faecium reduced the pH by producing organic acids during fermentation, and the gelatinization of agar was destroyed when pH value was lower than 4. Conclusion Bacteria produced organic acids that decreased the pH of culture medium during fermentation, which contributed to the destroy of agar gelatination.