木质素磺酸盐好氧降解菌的筛选及降解特性

The isolation and degradation characteristics of lignosulfonate-degrading The isolation and degradation characteristics of lignosulfonate-degrading aerobic bacterial strains

木质素是结构复杂的难降解有机物,研究其微生物降解机制对解决制浆造纸黑液处理问题,促进木质纤维素的再生利用具有重要意义.从制浆造纸厂活性污泥样本中分离出5株以木质素磺酸盐为唯一碳源和能源的好氧细菌.选取降解性能优异的菌株,考察温度、pH、碳氮比对该菌株生长和降解效果的影响,并对降解后木质素的官能团、元素组成变化和降解产物进行分析,推测木质素降解机制.结果显示:5株细菌均可有效降解木质素,其中菌株Sphingobacterium sp.HY-H的降解能力最强.通过正交试验确定菌株HY-H的最佳处理条件为温度30℃,pH=7.0,碳氮比5:1.在此条件下,菌株HY-H对木质素磺酸盐(1g L^(-1))的5 d降解率为30.6%.降解后木质素的酚羟基和甲氧基含量减少,羰基和羧基含量增加.分析木质素官能团变化及其降解产物认为,木质素降解过程中主要发生了α羟基氧化、β-O-4键断裂、脱甲基及脱羧作用,最终生成CO_2.本研究表明,菌株HY-H具有较好的木质素磺酸盐降解能力,可用于制浆造纸废水的生物处理.

Lignin is a refractory organic compound with complex structure. For promoting the recycling of lignocellulose, we need to study the microbial degradation mechanism of lignin in mitigating pollution caused by pulp and paper-making black liqour. In this research five aerobic bacterial strains utilizing lignosulfonate as a sole carbon and energy source were isolated from activated sludge in a pulp and paper mill. A strain with better degradation efficiency was then selected to investigate the effect of t emperature, pH and C/N ratio on its growth and degradation performance. Moreover, changes of functional groups and elemental compositions in residual lignosulfonate and the metabolic products were analyzed to speculate the degradation mechanisms. The results showed that all five bacterial strains were capable of degrading lignosulfonate, with Sphingobacterium sp. HY-H showing the best performance. The optimal conditions for strain HY-H were determined by Taguchi＇s orthogonal matrix method to be initial pH of 7.0, temperature of 30 ℃, and C/N ratio of 5：1. Under these conditions, the lignosulfonate degradation capacity of strain HY-H（ini tial lignosulfonate concentration of 1 g L^（-1）） could reach 30.6% after 5 days. During the process, contents of phenolic hydroxyl and methoxyl groups decreased, but those of carbonyl, carboxyl and sulfonate groups increased. The results indicated that lignosulfonate is degraded to carbon dioxide via oxidation of α-hydroxyl groups, cleavage reaction of β-O-4, demethylation and decarboxylation. The strain HY-H coul d effectively degrade lignosulfonate, thus having a great application prospect for the bio treatment of pulp and paper-making wastewater.