复合型生物絮凝剂产生菌筛选及絮凝机理研究

采用纤维素降解菌和絮凝菌组成复合型生物絮凝剂产生菌菌群，进行两段式发酵，利用纤维素为底物，生产复合型生物絮凝剂．将高效絮凝菌F2、F3、F5和F6进行双菌混合培养的正交试验，发现F2和F6组合絮凝活性最佳，且均优于单菌．确定该复合型生物絮凝剂HITM02的有效成分存在于发酵液中，主要是细菌的代谢产物．有效成分为蛋白质、多糖和多肽类物质，其中蛋白质的含量为5．4％，总糖含量为1．76％，还原糖未检出．这些有效成分与发酵过程中纤维素等的代谢残留物共同作用，具有优良的絮凝能力．絮凝机理包括蛋白质等两性电解质的电中和作用；蛋白质、多肽、多糖等高分子物质和纤维素等的代谢残留物共同具有的吸附架桥作用．

Screening of complex bioflocculant producing bacterium and their flocculating mechanism

Twelve strains of bacteria, which had the ability of producing bioflocculant, were obtained among 132 bacterial strains isolated from activated sludge samples. The flocculating efficiencies for F2, F3, F5 and F6 were all above 80%. Taking cellulose as substrate, which contains decomposing bacteria and flocculants-producing bacteria, a kind of complex bioflocculant (HITM02) was obtained through two-step fermentation. Every two strains of the bacteria among the 4 strains obtained above were selected to process the mixed culture by orthogonal experiment. Results showed that the combination of F2 and F6 strains possessed the best flocculating activity and was higher than that of any pure strains. It had been confirmed that effective compositions of HITM02 were polysaccharide (1.76%), protein and polypeptide (5.4%). These materials together with the fermentation residue of the cellulose possess the flocculating effect. The flocculating mechanisms of complex bioflocculants include: (1) adsorption and charge neutralization of ampholyte such as protein and polypeptide, (2) bridging of polysaccharide and the cellulose fermentation residue.