Rhizobium fermentation produces a large amount of extracellular mucus, so the solid-liquid separation of mucus becomes very difficult. In order to reduce the difficulty in bacteria collection, 7 flocculants were used to treat fermentation broth at an optimized fermentation level and evaluate the flocculation effect through flocculation rate, protein removal rate, polysaccharide removal rate and supernatant microorganisms content in this study. The results showed that aluminium polychlorid had the highest flocculation rate, high protein removal rate and polysaccharide removal rate, but a low supernatant microorganisms content with the serious phenomenon of adhering to wall; and cationic polyacrylamide performed a good effect of supernatant microorganisms content and polysaccharide removal rate, with a little wall-adhering phenomenon. In summary, the cationic polyacrylamide was the most suitable flocculant to Rhizobium astragalus for the solid-liquid separation of mucus.%根瘤菌发酵会产生大量的胞外粘液,使发酵液变得十分粘稠,从而严重影响发酵液的固液分离.为降低发酵液的菌体收集难度,研究在优化根瘤菌发酵水平的基础上,选用7种絮凝剂对发酵液进行处理,以絮凝率、蛋白去除率、多糖去除率、上清液菌体含量为指标进行筛选.结果表明:聚合氯化铝(50 mg/L)絮凝速率最快,蛋白多糖去除率高,但粘壁现象严重,上清菌体含量少;而阳离子聚丙烯酰胺(100 mg/L)表现出良好的上清菌体含量以及多糖去除率,且粘壁现象少,最适用于紫云英根瘤菌发酵液多糖去除和菌体的收集.
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