Baptista Marlene, Cunha Joana T, Domingues Lucília
CEB-Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
J Fungi (Basel). 2021 Dec 7;7(12):1047. doi: 10.3390/jof7121047.
The establishment of lignocellulosic biorefineries is dependent on microorganisms being able to cope with the stressful conditions resulting from the release of inhibitory compounds during biomass processing. The yeast has been explored as an alternative microbial factory due to its thermotolerance and ability to natively metabolize xylose. The lignocellulose-derived inhibitors furfural and 5-hydroxymethylfurfural (HMF) are considered promising building-block platforms that can be converted into a wide variety of high-value derivatives. Here, several strains, isolated from cocoa fermentation, were evaluated for xylose consumption and tolerance towards acetic acid, furfural, and HMF. The potential of this yeast to reduce furfural and HMF at high inhibitory loads was disclosed and characterized. Our results associated HMF reduction with NADPH while furfural-reducing activity was higher with NADH. In addition, furans' inhibitory effect was higher when combined with xylose consumption. The furan derivatives produced by in different conditions were identified. Furthermore, one selected isolate was efficiently used as a whole-cell biocatalyst to convert furfural and HMF into their derivatives, furfuryl alcohol and 2,5-bis(hydroxymethyl)furan (BHMF), with high yields and productivities. These results validate as a promising microbial platform in lignocellulosic biorefineries.
木质纤维素生物精炼厂的建立取决于微生物能否应对生物质加工过程中因抑制性化合物释放而产生的压力条件。由于酵母具有耐热性和天然代谢木糖的能力，它已被探索作为一种替代微生物工厂。木质纤维素衍生的抑制剂糠醛和5-羟甲基糠醛（HMF）被认为是有前景的基础平台，可以转化为多种高价值衍生物。在此，对从可可发酵中分离出的几种酵母菌株进行了木糖消耗以及对乙酸、糠醛和HMF耐受性的评估。揭示并表征了这种酵母在高抑制负荷下还原糠醛和HMF的潜力。我们的结果表明，HMF的还原与NADPH相关，而糠醛还原活性在NADH存在时更高。此外，呋喃与木糖消耗同时存在时的抑制作用更强。鉴定了酵母在不同条件下产生的呋喃衍生物。此外，一种选定的分离株被有效地用作全细胞生物催化剂，将糠醛和HMF转化为它们的衍生物糠醇和2,5-双（羟甲基）呋喃（BHMF），产率和生产率都很高。这些结果证实酵母是木质纤维素生物精炼厂中一个有前景的微生物平台。
