工业酿酒酵母菌株KF-7对发酵抑制物的耐受性

Evaluation of the inhibitor-tolerance of industrial aluation of the inhibitor-tolerance of industrial Saccharomyces cerevisiae Saccharomyces cerevisiae strain KF-7

木质纤维素原料预处理过程中产生的抑制物是燃料乙醇发酵的一大障碍,要求工业酿酒酵母菌株具有优秀的抑制物耐受能力.利用平板培养和批次发酵两种方式系统评价了弱酸抑制物(乙酸、甲酸、乙酰丙酸)、呋喃类抑制物[糠醛和5-羟甲基糠醛(HMF)]、酚类抑制物(香草醛、丁香醛、苯酚)对工业酿酒酵母菌株KF-7生长和发酵的影响.结果显示,菌株KF-7在批次发酵时细胞生长对抑制物的耐受性优于平板培养.低浓度的抑制物虽然对菌株的生长有一定的抑制作用,但对乙醇的产生具有一定的促进作用;高浓度抑制物显著抑制了菌株的生长,降低了葡萄糖的代谢速率,抑制了乙醇的产生.菌株KF-7对甲酸耐受能力强于乙酸,对乙酰丙酸的耐受能力较弱.在平板生长评价中,糠醛对菌株生长的抑制作用强于HMF,但在批次发酵过程中HMF的抑制作用强于糠醛;该菌株代谢糠醛的能力强于代谢HMF的能力.香草醛对菌株的抑制作用最强,丁香醛相对较弱.在秸秆水解液中,菌株KF-7也表现出良好的乙醇发酵性能.菌株KF-7无论在单一抑制物、混合抑制物或实际水解液条件下发酵,均能达到较高的乙醇收率.本研究表明,菌株KF-7适用于纤维素原料燃料乙醇工业化生产过程.

Inhibitors produced during the pretreatment and saccharification process are a big obstacle in ethanol fermentation duringthe production of fuel ethanol from lignocellulosic biomass. The industrial strain used for ethanol fermentation should have excellent inhibitor-tolerance. In this study, the effects of inhibitors, including weak acids （acetic, formic and levulinic acids）, furans （furfural and 5-hydroxymethl-2-furaldehyde （HMF））, phenolics （syringaldehyde, vanillin and phenol）, on the growth and fermentation of the industrial Saccharomyces cerevisiae strain KF-7 were evaluated through plate cultivation and batch fermentation. The results showed that cells grew better in batch fermentation than on plate cultivation at the same concentrations of inhibitors. Low concentrations of inhibitors inhibited the growth but increased ethanol productio.n. The growth was severely inhibited and sugar consumption delayed with inhibitors of high concentration. The strain was more tolerant to formic acid than to acetic acid. Fttrfural showed much greater inhibition on the growth than HMF in plate cultivation, but less inhibition in batch fermentation. The strain metabolizes furfural better than HMF. Plate cultivation and batch fermentation results showed an inhibitory effect order of vanillin 〉 phenol 〉 syringaldehyde. Strain KF-7 showed good tolerance to most inhibitors and good fermentation ability for rape straw hydrolysate, achieving high ethanol yields in fermenting with one single inhibitor or mixed inhibitors or straw hydrolysate. These results suggested that industrial S. cerevisiae strain KF-7 has high potential application value in lignocellulosic bioethanol production.