Background Vanillin is the main byproduct of alkaline-pretreated lignocellulosic biomass during the process of fermentable-sugar production and a potent inhibitor of ethanol production by yeast. Yeast cells are usually exposed to vanillin during the industrial production of bioethanol from lignocellulosic biomass. Therefore, vanillin toxicity represents a major barrier to reducing the cost of bioethanol production. Results In this study, we analysed the effects of oxygen-radical treatment on vanillin molecules. Our results showed that vanillin was converted to vanillic acid, protocatechuic aldehyde, protocatechuic acid, methoxyhydroquinone, 3,4-dihydroxy-5-methoxybenzaldehyde, trihydroxy-5-methoxybenzene, and their respective ring-cleaved products, which displayed decreased toxicity relative to vanillin and resulted in reduced vanillin-specific toxicity to yeast during ethanol fermentation. Additionally, after a 16-h incubation, the ethanol concentration in oxygen-radical-treated vanillin solution was 7.0-fold greater than that from non-treated solution, with similar results observed using alkaline-pretreated rice straw slurry with oxygen-radical treatment. Conclusions This study analysed the effects of oxygen-radical treatment on vanillin molecules in the alkaline-pretreated rice straw slurry, thereby finding that this treatment converted vanillin to its derivatives, resulting in reduced vanillin toxicity to yeast during ethanol fermentation. These findings suggest that a combination of chemical and oxygen-radical treatment improved ethanol production using yeast cells, and that oxygen-radical treatment of plant biomass offers great promise for further improvements in bioethanol-production processes.

中文翻译：

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基于非热常压等离子体的氧自由基减轻酵母中木质素衍生的酚类毒性。

背景香兰素是在可发酵糖生产过程中碱预处理的木质纤维素生物质的主要副产物，并且是酵母产生乙醇的有效抑制剂。在从木质纤维素生物质生产生物乙醇的工业生产过程中，酵母细胞通常会接触香草醛。因此，香草醛毒性是降低生物乙醇生产成本的主要障碍。结果 在这项研究中，我们分析了氧自由基处理对香草醛分子的影响。我们的结果表明，香草醛转化为香草酸、原儿茶醛、原儿茶酸、甲氧基氢醌、3,4-二羟基-5-甲氧基苯甲醛、三羟基-5-甲氧基苯，以及它们各自的开环产物，与香兰素相比，其毒性降低，并导致乙醇发酵过程中香兰素对酵母的特异性毒性降低。此外，在孵育 16 小时后，经氧自由基处理的香草醛溶液中的乙醇浓度是未经处理的溶液的 7.0 倍，与经过氧自由基处理的碱预处理稻草浆观察到的结果相似。结论 本研究分析了氧自由基处理对碱预处理稻草浆中香草醛分子的影响，从而发现该处理将香草醛转化为其衍生物，从而降低了乙醇发酵过程中香草醛对酵母的毒性。这些发现表明，化学和氧自由基处理的结合提高了酵母细胞的乙醇产量，