Abstract: The pretreatment of 2,3-butanediol fermentation broth by chitosan flocculation was investigated. Using sodium alginate as coagulant, the effects of chitosan molecular weight, chitosan dosage, coagulant dosage, pH and turbidity time on the flocculation of fermentation broth were investigated, respectively. The performance was evaluated by flocculation ratio. According to the results, the optimum flocculation conditions for Klebsiella pneumoniae cells were as follows: 0.375 g/L of chitoson with 40 kDa molecular weight, 0.250 g/L of sodium alginate, pH 5.0, 30 min of stirring time and 1 h of settlement time. The flocculation rate reached 98%, the retained ratio of 2,3-butanediol reached 99%, and the supernatant in the broth was clear. After flocculation the cells of Klebsiella pneumoniae in the flocs grew well (OD 13.5) and were used repeatedly.

Key words: 3-butanediol, flocculation, chitosan, fermentatio

摘要： 研究了用壳聚糖/海藻酸钠复合絮凝剂处理2,3-丁二醇发酵液的工艺条件，以絮凝率为指标，考察了壳聚糖分子量、壳聚糖用量、海藻酸钠助凝剂用量、发酵液pH值、搅拌时间等因素对处理效果的影响，确定了适于2,3-丁二醇发酵液体系的絮凝工艺. 结果表明，最佳操作条件为壳聚糖分子量40 kDa，壳聚糖用量0.375 g/L，海藻酸钠助凝剂用量0.250 g/L，发酵液pH 5.0，搅拌时间30 min，静置1 h. 该条件下，絮凝率可达98%以上，2,3-丁二醇保留率约为99%，且絮凝后上清液清澈、透明. 絮凝后的菌体可再次利用，发酵过程中菌体最高浓度(OD值)可达13.5，其转化能力与絮凝前相当.

关键词: 3-丁二醇, 絮凝, 壳聚糖, 发酵