木质素中酚酸物质对于丙酮丁醇发酵的影响

Promotion and Inhibition Effects of Phenolic Acids on Clostridium Acetobutylicum Fermentation

木质纤维素预处理过程中产生的酚酸类物质影响丙酮丁醇梭菌生长代谢,研究了酚酸结构类型化合物阿魏酸、香草酸、丁香酸和对羟基苯甲酸对于丁醇发酵的影响。研究发现添加低浓度酚酸(低于100 mg/L)对丁醇发酵与丙酮丁醇梭菌生长具有促进作用,当加入50 mg/L对羟基苯甲酸,实验组丁醇产量比对照组高21.32%,加入100 mg/L香草酸组生物量为对照组的4.50倍,而酚酸浓度继续增大时(高于100 mg/L),呈现明显抑制作用,且浓度越高,抑制作用越强,当香草酸浓度为1 000 mg/L时,丁醇产量抑制率达到96.67%,4种酚酸物质浓度为1 000 mg/L时所有实验组生物量为0;据此结果提出了通过加大接种量增强菌体抑制点来解除抑制的方法,接种量增加到30%,不脱毒直接发酵可得9.16 g/L丁醇,达到正常发酵水平。不同种类的酚酸物质对于丁醇发酵与生长的影响总体趋势是一致的,但其毒性大小不尽相同,因此进一步选用定量构效方法 (QSAR)考察酚酸物质对于丙酮丁醇发酵的毒性影响因素,发现酚酸物质其毒性与电离常数和分子质量相关性非常显著,相关系数分别为0.816和0.876,即电离常数越小,分子质量越小,则毒性越大,与疏水性呈现不显著的负相关。

Phenol acids generated during lignocellulose pretreatment process can affect the growth and metabolism of Clostridium acetobutylicum.Promotion and inhibition effects of ferulic acid,vanillic acid,syringic acid and p-hydroxybenzoic acid on butanol fermentation were investigated.The results showed that low concentration of phenolic acids（lower than 100 mg/L） played a promotion role in butanol fermentation.Butanol yield was increased by 21.72% when 60 mg/L hydroxybenzoic acid was added into fermentation culture,whereas biomass reached 4.50 times that of the control group when 100 mg/L vanillic acid was added.However as the inhibitor concentrations increased（higher than 100 mg/L）,the effect of inhibition became more obvious.Butanol production was inhibited 96.67% when 1 000 mg/L of vanilla acid was added,and the biomass of all experimental groups failed to detect.A way of direct butanol fermentation without detoxification steps by increasing the inoculation rate to enhance bacterial inhibition point was established.Butanol yield of 9.16 g/L,which was the normal fermentation level,was obtained by 30% inoculation.These four phenolic acids had similar effects on butanol fermentation,but differed in their toxicity to bacteria.The toxicity of phenolic acids was significantly correlated with their ionization constants and molecular weight,and the correlation coefficients were 0.816 and 0.876,respectively,by quantitative structure activity relationships（QSAR） method,i.e.the smaller ionization constants and molecular weight,the greater the toxicity.But the toxicity presented no significant negative correlation with the hydrophobic.