镉胁迫对节杆菌(Arthrobacter sp．)和芽孢杆菌(Bacillussp．)生理生化特性的影响

Effects of Cd(Ⅱ) on the physico-biochemical behaviors of Arthrobacter sp. and Bacillus sp.

将节杆菌和芽孢杆菌分别暴露于不同质量比的镉溶液中,进行不同暴露时间的急性毒性试验。结果表明,20 mg/kg的Cd(II)处理会使节杆菌中还原型谷胱甘肽(GSH)质量浓度显著降低,细胞膜脂质过氧化产物——硫代巴比妥酸活性物质(TBARS)浓度显著升高;0.2mg/kg的Cd(II)处理会使芽孢杆菌中GSH质量浓度、过氧化氢酶(CAT)活性显著降低。节杆菌的可溶性蛋白、可溶性糖质量浓度随暴露时间延长而减少,GSH质量浓度、CAT和超氧化物歧化酶(SOD)活性随暴露时间延长而增加,TBARS浓度呈先减后增的变化趋势;芽孢杆菌的可溶性蛋白质量浓度、CAT活性和TBARS浓度呈先增后减的变化趋势,可溶性糖、GSH质量浓度和SOD活性呈先减后增的变化趋势。镉处理对节杆菌和芽孢杆菌具有一定的胁迫作用,两种菌通过启动不同的抗性系统来抵抗外界胁迫。

This paper is engaged in the study of the effects of Cd（II） on the physico-biochemical behaviors of Arthrobacter sp. through tox- icity testing. The toxicity test has been arranged by putting the an- tioxidant system of Arthrobacter sp. and Bacillus sp. under the expo- sure to different concentrations of Cd（II） for different lengths of test- ing time. The results of our testing show that Cd（II） has a strong im- pact on the antioxidant system of Arthrobacter sp. and Bacillus sp.. However, it is possible to reduce GSH content and increase TBARS content of Arthrobacter sp. significantly by letting Cd（II） treated with 20 mg/kg. Our testing proves that it is possible to reduce the GSH content and CAT activity of Bacillus sp. significantly by treating Cd（II） with 0.2 mg/kg, for the Arthrobacter sp., the soluble protein and soluble sugar content can be reduced through prolonging the time of exposure. On the contrary, it is also possible to increase the GSH content and the CAT ＆ SOD activity by means of prolonging the ex- posure, with the TBARS content decreased first and increased later, consequently. Besides, the SOD activity of the soluble sugar and the content of GSH have also been found decreased first and then in- creased. However, the increase of Cd（II） concentration proves to in- hibit the SOD activity in Arthrobacter sp., but promote the SOD ac- tivity and the growth of soluble protein content in Bacillus sp.. On the other hand, Cd（fI） has also been found inducing Bacillus sp. It has also to point out that the enhancement of SOD activity and the in- crease of soluble protein content can result in a self-protective effect of the stress response. With the prolonging of exposure of Cd（II） so- lution to Arthrobacter sp. and Bacillus sp. in different durations, it is favorable to increase the GSH content and SOD activity. Our testing has also demonstrated that bacterial SOD and GSH synthesis is likely to induce the metal toxicity. Therefore, it is necessary to reduce the soluble protein content to inhibit the soluble protein synthesis of the cadmium ion with the Arthrobacter sp. so as to alleviate the damage of the heavy metals on the cellular oxides and induce the protein degradation. The results of our testing indicate that the two kinds of bacteria can both be employed in the different resistance systems to resist such stress.