出芽短梗霉产聚苹果酸发酵条件的优化

Optimization of fermentation conditions for polymalic acid production by Aureobasidium pullulans BK-10

【背景】出芽短梗霉可发酵葡萄糖生成聚苹果酸,但存在转化率和转化效率低等瓶颈,阻碍其实现商业化生产。【目的】通过优化发酵培养条件,提高出芽短梗霉的聚苹果酸产量、糖酸转化率和生产强度。【方法】采用单因素试验优化适宜出芽短梗霉BK-10菌株产生聚苹果酸的培养条件,通过Plackett-Burman法对培养基组分筛选显著性影响因素,并对其培养基中无机盐进行正交试验优化,最后进行5 L发酵罐验证。【结果】最优培养基配方和培养条件:100 g/L葡萄糖,1.5 g/L尿素,0.20 g/L KH_2PO_4,0.20 g/L ZnSO_4,0.05 g/L MgSO_4,0.75 g/L KCl,30 g/L CaCO_3,0.01%吐温-80,发酵温度26°C,250 mL摇瓶装液量50 mL。【结论】通过优化,聚苹果酸的糖酸转化率达到0.71 g/g,生产强度达到0.89 g/(L·h),较优化前分别提高了18.33%和71.15%,为发酵葡萄糖合成聚苹果酸进而生产L-苹果酸工艺的工业化生产奠定经济性基础。

[Background] Bottleneck problems such as poor yield and low productivity had been hindering the progress in commercial production of polymalic acid from glucose by Aureobasidium pullulans. [Objectivel To enhance polymalic acid yield and productivity from Aureobasidium pullulans BK-10 by optimizing the fermentation medium and conditions. [Methods] Single-factor experiment, Plackett-Burman design and orthogonal experiment were adopted to evaluate the importance of various fermentation medium ingredients and optimize kinds of fermentation conditions. A 5 L fermentor experiment was conducted to verify the above optimized conditions. [Results] The optimum fermentation medium consisted of 100 g/L glucose, 1.5 g/L urea, 0.20 g/L KH2PO4, 0.20 g/L ZnSO4, 0.05 g/L MgSO4, 0.75 g/L KCl, 30 g/L CaCO3, 0.01% Tween-80, the optimal fermentation temperature was found 26℃and the optimal working volume was 50 mL of fermentation medium in a 250 mL flask. [Conclusion] Yield of polymalic acid from glucose reached 0.71 g/g with an increase of 18.33%, and the productivity was 0.89 g/（L·h） which was increased by 71.15% as compared with the unoptimized conditions. These results show great economical potential for commercial production of polymalic acid even or L-malic acid by fermentation from glucose.