尖孢镰刀菌LD105产抑菌多糖固态发酵条件优化

Optimization of Solid-State Fermentation Conditions for Antibacterial Polysaccharide Production by Fusarium oxysporum LD105 Using Response Surface Methodology

以云南昆明玛卡根际土壤中分离到的尖孢镰刀菌LD105作为发酵菌种,以多糖产量和抑菌率为评价指标,用响应面法优化尖孢镰刀菌产抑菌多糖固态发酵工艺。通过单因素试验,筛选出发酵时间、初始含水量、蔗糖和KH_2PO_4添加量4个显著影响因素,研究其交互作用,优化得出最佳发酵工艺条件:发酵时间5 d、初始含水量54%、发酵温度28℃、初始pH 6、蔗糖添加量3%、KH_2PO_4添加量0.3%、接种量10%、蛋白胨添加量1.5%、装料量10 g(250 mL锥形瓶为发酵容器)。在此优化条件下,尖孢镰刀菌固态发酵产多糖抑菌率和多糖产量分别为37.6%和30.2 mg/g,抑菌率和多糖产量比优化前分别提高了1.8倍及1.5倍。

Response surface methodology was employed to optimize the solid-state fermentation process of Fusarium oxysporum LD105, isolated from maca rhizosphere soil in Kunming, Yunnan Province, for improved production of antibacterial polysaccharides. Polysaccharide yield and antibacterial activity were used as response variables. Using one-factor-at-a-time method, fermentation time, initial moisture content, sucrose and KH2PO4 concentration were identified as main factors that significantly influence the responses. The three-dimensional response surfaces were generated to study the interaction among the four factors. The results showed that the optimal fermentation conditions were as follows: fermentation time 5 d; sucrose concentration 3%; fermentation temperature 28 ℃, initial moisture content 54%, KH2PO4 concentration 0.3%, inoculum size 10%, initial medium pH 6, peptone concentration 1.5%, and 10 g of medium contained in a 250 mL conical flask. Under these conditions, the percentage inhibition of Escherichia coli and the polysaccharide yield were 37.6% and 30.2 mg/g, which were increased by 2.8 and 2.5 folds as compared to that obtained using the unoptimized medium, respectively.