一株聚丙烯酰胺降解菌的降解性能和机理

Degradation characteristics and mechanism of a polyacrylamide-degrading bacteria strain

从大庆油田筛选到一株聚丙烯酰胺降解菌,经16SrDNA序列分析鉴定其为褐栗芽孢杆菌(Bacillus badius),命名为JHW-1.将降解菌扩培后,接种至以聚合物为唯一有机营养源的培养基,在41℃、pH=7.2条件下培养7d,聚合物粘度较无菌对照降低48.5%.在培养基中分别添加少量FeSO4和MnSO4、酵母粉、葡萄糖后,聚合物粘度较对照降低了57.4%、72.5%、86.2%.降解菌在同时添加了FeSO4、MnSO4和葡萄糖的聚合物培养基中培养7d后,聚合物降粘率达到91.4%,相对分子量由106～107降至103～106,且聚合物质量减少约8%.降解菌能够利用分泌到培养液中的胞外酶水解聚合物的酰胺基团,使其变为羧酸;同时,降解菌在生长过程中还会释放非蛋白还原性物质,它们同胞外酶共同作用使碳链断裂.

A polyacrylamide-degrading bacterial strain was isolated from the Daqing oilfield,and named JHW-1.Through 16SrDNA analysis,it was identified as belonging to Bacillus badius.In the laboratory,after cultivation,JHW-1 was inoculated in the culture medium with the polyacrylamide as the sole organic carbon source.After 7 d cultivation at 41℃ and pH 7.2,the viscosity of the polyacrylamide declined 48.5% in comparison with the control without JHW-1.When FeSO4＋MnSO4,yeast extract and glucose are added to the above culture medium,the viscosity decreased 57.4%,72.5%,86.2% respectively.After JHW-1 was grown for 7 days in the culture medium with FeSO4,MnSO4 and glucose,the viscosity reduction rate of the polymer reached 91.4%,and the relative molecular weight of the polymer decreased from 10^6～10^7 to 10^3～10^6,while the quality of polymer reduced about 8%.An extracellular enzyme secreted by JHW-1 hydrolyzed the acidamide radical of the polymer and turned it into carboxylic acid.Meanwhile,during the process of reproduction,JHW-1 released non-protein reducing substances which cooperated with the extracellular enzyme in breaking down the carbon chains.