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木质素降解产物对微生物产生的抑制作用,是燃料乙醇生物炼制的主要瓶颈之一。本文以树干毕赤酵母为发酵菌株,研究木质素降解产物中3种酚酮类(4-羟基苯乙酮、4-羟基-3-甲氧基苯乙酮、4-羟基-3,5-二甲氧基苯乙酮)对其木糖乙醇发酵及酵母细胞脂肪酸组成的影响。采用高效液相色谱(HPLC)和气相色谱-质谱联用(GC/MS)技术对乙醇发酵性能和酵母细胞脂肪酸组成进行分析。研究结果表明,酚酮类物质对乙醇发酵呈现抑制作用且其分子量越低抑制作用越明显,当4-羟基苯乙酮浓度为1.50 g/L时,发酵24 h的木糖利用率、乙醇得率和乙醇浓度分别下降了42.47%、5.30%和9.76 g/L;培养基中存在酚酮类物质时,酵母细胞中的不饱和脂肪酸的比例上升,添加1.50 g/L的3种酚酮类物质后,树干毕赤酵母细胞不饱和脂肪酸和饱和脂肪酸的比例从原来的2.58分别上升到3.03、3.06和3.61,酵母细胞膜的流动性随之上升,不稳定性提高。因此,酚酮类物质能够降低酵母生长、提高不饱和脂肪酸的比例以及降低乙醇发酵能力,有效降低或去除木质素降解产物含量是提高木质纤维原料生物炼制的关键。
The degradation of microorganisms caused by lignin degradation products is one of the major bottlenecks in the bio-refining of fuel ethanol. In this paper, Pichia stipitis was used as a fermentative strain to study the effects of three phenolic ketones (4-hydroxyacetophenone, 4-hydroxy-3-methoxyacetophenone, Dimethoxyacetophenone) on the xylose ethanol fermentation and the fatty acid composition of yeast cells. The ethanol fermentation performance and fatty acid composition of yeast cells were analyzed by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC / MS). The results showed that phenolic ketones showed inhibitory effect on ethanol fermentation and the lower the molecular weight was, the more obvious inhibition was. When the concentration of 4-hydroxyacetophenone was 1.50 g / L, the xylose utilization, Rate and ethanol concentration decreased by 42.47%, 5.30% and 9.76 g / L, respectively. The proportion of unsaturated fatty acids in yeast cells increased in the presence of phenolic ketones in the medium. Three kinds of phenolic ketones were added at 1.50 g / L After substance, the proportion of unsaturated fatty acids and saturated fatty acids in Pichia pastoris increased from 2.58 to 3.03, 3.06 and 3.61 respectively, the fluidity of yeast cell membrane increased and the instability increased. Therefore, phenolic ketones can reduce yeast growth, increase the proportion of unsaturated fatty acids and reduce ethanol fermentation capacity, and effectively reduce or remove the content of lignin degradation products to improve lignin fiber biological refining key.