Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
Nat Commun. 2021 Aug 17;12(1):4975. doi: 10.1038/s41467-021-25241-y.
Plant cell wall hydrolysates contain not only sugars but also substantial amounts of acetate, a fermentation inhibitor that hinders bioconversion of lignocellulose. Despite the toxic and non-consumable nature of acetate during glucose metabolism, we demonstrate that acetate can be rapidly co-consumed with xylose by engineered Saccharomyces cerevisiae. The co-consumption leads to a metabolic re-configuration that boosts the synthesis of acetyl-CoA derived bioproducts, including triacetic acid lactone (TAL) and vitamin A, in engineered strains. Notably, by co-feeding xylose and acetate, an enginered strain produces 23.91 g/L TAL with a productivity of 0.29 g/L/h in bioreactor fermentation. This strain also completely converts a hemicellulose hydrolysate of switchgrass into 3.55 g/L TAL. These findings establish a versatile strategy that not only transforms an inhibitor into a valuable substrate but also expands the capacity of acetyl-CoA supply in S. cerevisiae for efficient bioconversion of cellulosic biomass.
植物细胞壁水解产物不仅含有糖，还含有大量的乙酸盐，乙酸盐是一种发酵抑制剂，会阻碍木质纤维素的生物转化。尽管在葡萄糖代谢过程中乙酸盐具有毒性且不可消耗，但我们证明了工程化的酿酒酵母可以快速与木糖共同消耗乙酸盐。共同消耗导致代谢重新配置，从而促进了由乙酰辅酶 A 衍生的生物制品的合成，包括三醋酸甘油酯 (TAL) 和维生素 A，在工程菌株中。值得注意的是，通过共喂养木糖和乙酸盐，一株工程菌株在生物反应器发酵中产生 23.91g/L 的 TAL，产率为 0.29g/L/h。该菌株还可以将柳枝稷的半纤维素水解物完全转化为 3.55g/L 的 TAL。这些发现建立了一种通用策略，不仅将抑制剂转化为有价值的底物，还扩大了酿酒酵母中乙酰辅酶 A 供应的能力，以有效生物转化纤维素生物质。
