Pseudomonas S2-3菌株对Cr(Ⅵ)的耐受性及去除

Investigation of Cr(Ⅵ) tolerance and removal by Pseudomonas S2-3

针对分离得到的Cr(VI)耐受菌株S2-3进行了基本生长特征、16S rRNA序列分析、Cr(VI)对菌株生长影响、菌株生长代谢与铬的去除的关系等研究。结果表明:该菌株属于假单胞菌,与Pseudomonas chlororaphis(Z76673)相似性最高(99.8%);Cr(VI)对菌株生长有着明显的抑制作用,其耐受上限可达到1 500 mg/L左右;Cr(VI)导致菌体细胞大小分布变宽,同时使得细胞表面的—OH和—NH基团减少。当初始Cr(VI)浓度为100 mg/L时,48 h内菌株S2-3对Cr(VI)去除效率可达到85.9%,对总铬去除率为24.1%。在高Cr(VI)浓度(1 000 mg/L)下,菌株对Cr(VI)和总铬仍有一定的去除效果,分别为58.7%和3.3%。菌株S2-3主要通过还原Cr(VI)的方式去除Cr(VI)。Cr(VI)的还原与菌液ORP以及细胞表面的—OH和—NH有关;总铬的去除不是因为形成了氢氧化铬沉淀,而是Cr(III)被吸附在了细胞表面的—CO上。

In this study,we isolated a strain denoted S2-3,determined its basic physiological characteristics,and performed 16 S rRNA gene sequencing. In addition,we examined the effect of Cr（Ⅵ） on bacterial growth and the relationship between bacterial growth and Cr（Ⅵ） removal. Results indicated that the isolated strain showed 99. 8% homology to Pseudomonas chlororaphis（ Z76673）. Cr（Ⅵ） significantly inhibited the growth of S2-3 cells. However,S2-3 cells showed high tolerance toward 1 500 mg / L Cr（Ⅵ）. Exposure of S2-3 to Cr（Ⅵ）increased cell size distribution and decreased the number of —OH and —NH groups on the surface of S2-3 cells.Incubation of S2-3 with an initial Cr（Ⅵ） concentration of 100 mg / L for 48 h increased Cr（Ⅵ） and total Cr removal by 85. 9% and 24. 1%,respectively. Moreover,incubation of S2-3 with a higher initial Cr（Ⅵ） concentration of1 000 mg / L increased Cr（Ⅵ） and total Cr removal by 58. 7% and 3. 3%,respectively. Mechanism of Cr（Ⅵ）removal is ascribed to a Cr（Ⅵ） reduction reaction which is related to both oxidation reduction potential and—OH,—NH groups on the cell surface. Further,removal of total Cr may have occurred because of the adsorption of Cr（ III） by—CO group on the surface of S2-3 cells and not because of chromium hydroxide precipitation.