从海水环境分离筛选甘蔗渣纤维素降解菌

【目的】筛选海水环境高效甘蔗渣纤维素降解菌，并研究不同菌株间的混合发酵对甘蔗渣纤维素酶活力的影响，为纤维素降解菌在海水养殖中的应用提供理论基础。【方法】采用刚果红染色法进行菌株初筛，利用DNS法测定各菌株胞外纤维素酶活力及不同菌株间的混合酶液与混合发酵酶液的纤维素酶活力。【结果】筛选得到两株具有较强纤维素分解能力的细菌菌株Z4和S5，经16S rRNA基因序列分析，初步鉴定为地衣芽孢杆菌(Bacillus licheniformis)。菌株S5具有最高的全酶活和甘蔗渣纤维素酶活，分别为1.16 U/mL和2.80 U/mL。菌株Z4与S5间混合发酵能明显提高菌株的纤维素酶活力，比S5单独发酵时全酶活、甘蔗渣纤维素酶活分别提高40.60%、14.21%。同时菌株S5与芽孢杆菌BZ5混合发酵也能提高其纤维素酶活力，比S5单独发酵时全酶活、甘蔗渣纤维素酶活分别提高6.23%、25.92%。【结论】筛选得到两株酶系较全且酶活较高的纤维素降解菌Z4、S5，适宜的混合发酵可明显提高纤维素降解能力，在海水养殖中有较大的应用前景。

Isolation and screening of bagasse-cellulose degrading-bacteria from seawater environment

[Objective] The aim of this study was to screen bagasse-cellulose degrading-bacteria from seawater environment and to research the influence on bagasse cellulose enzymatic activity by mixed-fermentation of strains. [Methods] Cellulose congo-red culture medium was used to screening, and extracellular enzyme activity as re-screening methods. [Results] Two strains (Z4 and S5) were isolated and identified as Bacillus licheniformis by 16S rRNA gene sequence similarity analysis. Strain S5 possessed the highest filter paper activity (FPA activity) and bagasse cellulose activity which were 1.16 U/mL and 2.80 U/mL respectively. Mixed-fermentation of Z4 and S5 could obviously increase in cellulose enzyme activity. FPA activity and bagasse cellulose activity increased by 40.60% and 14.21% compared to S5. Mixed-fermentation of S5 and Bacillus BZ5 increased FPA activity and bagasse cellulose activity by 6.23% and 25.92% respectively. [Conclusion] Mixed-fermentation can significantly improve the ability of cellulose degradation, Z-4 and S-5 have a potential application in mariculture.