纤维素降解菌XW08的筛选、鉴定及其降解条件优化

Screening of Cellulose-degrading Strain XW08 and Optimization of its Fermentation Condition

优化纤维素降解菌株XW08发酵产酶条件,可为该菌株在纤维素的生物降解提供试验依据.本文以长期堆积树木土壤和朽木为材料,从中分离并筛选出一株能有效降解纤维素的细菌菌株,命名为XW08,利用形态观察、理化性质及16S rDNA序列扩增和测序对其进行鉴定,结果显示菌株XW08在系统发育树上与Streptomyces exfoliatus HBUM174569和Streptomyces sp.MJM1121聚集在同一个分支中,属于放线菌属.发酵产酶条件优化结果表明,菌株XW08在碳源(淀粉)20 g/L,氮源(酵母膏)6 g/L,温度为35℃,pH为6.0,装液量70 mL/250 mL,培养72 h,菌株XW08的CMCase和FPase活力分别达到43.56、36.72 U/mL.表明菌株XW08具有良好的生物降解性能.

The fermentation conditions of cellulose degradation strain XW08 were optimized to provide experimental basis for cellulose biodegradation.A cellulose-degrading bacterial strain XW08 was isolated from the soil for long-term accumulation of trees and rotten wood.The strain XW08 was identified by morphological observation,physiological and biochemical analysis and 16S rDNA sequence analysis.The results showed that strain XW08 was clustered in the same branch with Streptomyces exfoliatus HBUM174569 and Streptomyces sp.MJM1121 on the phylogenetic tree.Therefore the strain XW08 belonged to Streptomyces.The optimum fermentation conditions for enzymatic production were acquired as follows:the starch(as carbon source)concentration 20 g/L,yeast extract(as nitrogen source)concentration 6.0 g/L,culture temperature 35℃,initial pH 6.0,filling capacity 50 mL(in 250 mL shaking bottle),culture time 72 h.Under these conditions,the CMCase and FPase activity of strain XW08 were 43.56U/mL and 36.72U/mL,respectively.Therefore,strain XW08 has good development value and application prospect in cellulose biodegradation.