高絮凝活性芽孢杆菌的筛选及其絮凝特性研究

Screening of a novel bioflocculant-producing strain of Bacillus sp.and research for its flocculation characteristics

采用平板分离法从土壤中分离芽孢杆菌,以发酵液对高岭土悬液絮凝效果为指标筛选高絮凝活性菌株,并通过细菌形态、生理生化特性和16S rDNA序列分析进行鉴定;同时考察发酵液加入量、Ca2+浓度和pH对絮凝效果的影响以及微生物絮凝剂在发酵液中的分布.结果表明:从土壤中分离筛选到1株具有高效絮凝活性的芽孢杆菌MBFF6,其絮凝率可达95.7%;根据细菌菌落形态、生理生化特性和16S rDNA序列分析,确定该菌株为巨大芽孢杆菌;其最佳絮凝条件为加入的菌液体积分数2%,Ca2+浓度4.5 mmol·L-1,pH 7.0;该微生物絮凝剂是细菌在生长过程中产生的胞外代谢产物,存在于发酵液中.

A novel bioflocculant-producing Bacillus sp.was isolated from soil by streak plate method,and screened out by an index that the fermentation broth flocculated kaolin suspension.The strain was identified by physiological and biochemical characteristics and 16S rDNA sequence analysis.The effect of the factors such as fermentation broth dosage,Ca2＋ concentration and pH on the flocculation were investigated.The results revealed that a novel bioflocculant-producing bacterium,named MBFF6,was isolated from soil and identified as Bacillus megaterium;its flocculating rate could achieve 95.7%;the optimal condition for flocculation was as follows： fermentation broth dosage of 2%,Ca2＋ concentration of 4.5 mmol·L-1 and pH 7.0.The bioflocculant was produced during the bacterial growth and was an extracellular product which was distributed in the culture broth.