以木糖为唯一碳源筛选了10株乙偶姻生产菌株,对乙偶姻产量最高菌株进行16S rDNA鉴定,测序结果表明该菌株为多粘芽孢杆菌,命名为LY107.经单因素实验优化培养条件为:培养温度37℃、pH值7.0、装液量15 mL/250 mL、接种量5％(体积比).采用葡萄糖—木糖(2∶1,质量比,下同)为碳源模拟木质纤维素水解液发酵生产乙偶姻,经Plackett-Burman(PB)实验和RSM优化培养基组分(g·L-2)为:葡萄糖—木糖(2∶1)60、蛋白胨5、酵母粉16.5、硫酸锰0.05、硫酸亚铁0.005、磷酸二氢钾0.1、乙酸钠2.47.在优化培养条件和培养基组分下,乙偶姻最高产量达23.9 g·L-1,葡萄糖—木糖转化率为79.9％.%Ten strains producing acetoin were screened using xylose as the sole carbon source.The relatively high acetoin producing strain from these ten strains was identified as Paenibacillus polymyxa LY107 based on its physiological and biochemical characteristics as well as the 16S rDNA sequence.The culture conditions were optimized by single factor experiment as follows:culture temperature of 37 ℃,pH value of 7.0,culture volume of 15 mL in 250 mL shake flask,inoculum amount of 5% (volume ratio).The Plackett-Burman (PB) design and response surface methodology (RSM) were employed to optimize the medium components for acetoin production by P.polymyxa LY107 through co-fermentation of glucose and xylose (2:1,mass ratio),which simulated the ratio of monosaccharide from cellulosic hydrolysate.The optimum medium components were obtained as follows: glucose-xylose 60 g · L-1,tryptone 5 g · L-1,yeast extract 16.5 g · L-1,MnSO4 0.05 g · L-1,FeSO4 0.005 g · L-1,KH2PO4 0.1 g · L-1,sodium acetate 2.47 g · L-1.Under above optimized culture conditions and medium components,the maximum acetoin concentration of 23.9 g · L-1 was obtained with 79.9% of glucose-xylose conversion rate.
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