等离子体诱导L型细菌形成和代谢改变的观察

目的研究大气辉光放电等离子体诱导L型细菌形成,探讨其杀菌机理。方法用诱导培养基培养和染色镜检方法及糖代谢检测进行了试验观察。结果经等离子体处理后培养基上大肠杆菌菌落数比对照组显著减少,多数形态正常。培养至第2日,有针尖大小白色菌落长出,第4日菌落呈白色,表面干燥粗糙,有的呈颗粒状,形状不规则;第4日之后菌落数不再增加。经革兰染色镜检发现,白色菌落的细菌形状变为圆形,大小不均,染色特性也发生改变呈紫蓝色,着色不均匀,经证实为L型细菌。金黄色葡萄球菌L型菌的形成比大肠杆菌少,并且随培养时间增加不明显。L型细菌的形成随等离子体作用时间的延长而降低,暴露时间超过180 s的样品没有观察到L型细菌形成。经等离子体处理后L型大肠杆菌不能分解蔗糖和甘露醇,L型金黄色葡萄球菌对蔗糖分解能力降低,不能分解甘露醇。结论等离子体可以诱导大肠杆菌和金黄色葡萄球菌形成L型细菌,改变其糖代谢,推测等离子体杀菌可能以破坏细菌细胞壁为主。

PLASMA INDUCES FORMATION OF BACTERIAL L- FORMS AND CHANGE OF METABOLISM

Objective To study formation of bacteria L-forms induced by atmospheric glow discharge plasma and to explore its germicidal mechanism.Methods Culture with induction culture medium,microscopic examination after staining and examination of sugar metabolism were used to carry out experimental observation.Results The E.coli colony count on the culture medium after exposure to plasma was significantly reduced as compared with the control group,but the morphology was normal.On second day of culture,white colonies of pinpoint size emerged.On fourth day,the colonies were white in color,their surfaces were dry and rough,some were granular and irregular in shape.The colony count did not increase any longer after fourth day.Microscopic examination after Gram's staining found that the bacteria of the white colony became spherical in shape,irregular in size and the staining characteristics also changed to purplish blue in color and inhomogeneous.These bacteria were confirmed to be bacterial L-forms.The L-forms of Staphylococcus aureus formed were less than those of Escherichia coli and did not significantly increase with increasing culture time.The formation of bacterial L-forms decreased with prolonging time of exposure to plasma and no bacterial L-forms formed after exposure for longer than 180 s.After exposure to the plasma,the L-forms of E.coli could not decompose sucrose and mannitol and those of S.aureus could not decompose mannitol and their ability to decompose sucrose decreased.Conclusions Plasma can induce E.coli and S.aureus to form bacterial L-forms and change their sugar metabolism.The germicidal action of plasma is inferred to be mainly due to destruction of bacterial cell wall.