Embrapa Agroenergia. Parque Estação Biológica, PqEB - W3 Norte Final, Postal code 70.770-901, Brasília-DF, Brazil.
Graduate Program in Chemical and Biological Technologies, Institute of Chemistry, University of Brasília, Campus Darcy Ribeiro, Postal code 70.910-900, Brasília-DF, Brazil.
FEMS Yeast Res. 2019 Jun 1;19(4). doi: 10.1093/femsyr/foz034.
Xylitol is a five-carbon polyol of economic interest that can be produced by microbial xylose reduction from renewable resources. The current study sought to investigate the potential of two yeast strains, isolated from Brazilian Cerrado biome, in the production of xylitol as well as the genomic characteristics that may impact this process. Xylose conversion capacity by the new isolates Spathaspora sp. JA1 and Meyerozyma caribbica JA9 was evaluated and compared with control strains on xylose and sugarcane biomass hydrolysate. Among the evaluated strains, Spathaspora sp. JA1 was the strongest xylitol producer, reaching product yield and productivity as high as 0.74 g/g and 0.20 g/(L.h) on xylose, and 0.58 g/g and 0.44 g/(L.h) on non-detoxified hydrolysate. Genome sequences of Spathaspora sp. JA1 and M. caribbica JA9 were obtained and annotated. Comparative genomic analysis revealed that the predicted xylose metabolic pathway is conserved among the xylitol-producing yeasts Spathaspora sp. JA1, M. caribbica JA9 and Meyerozyma guilliermondii, but not in Spathaspora passalidarum, an efficient ethanol-producing yeast. Xylitol-producing yeasts showed strictly NADPH-dependent xylose reductase and NAD+-dependent xylitol-dehydrogenase activities. This imbalance of cofactors favors the high xylitol yield shown by Spathaspora sp. JA1, which is similar to the most efficient xylitol producers described so far.
木糖醇是一种具有经济价值的五碳多元醇，可以通过微生物将木糖还原为可再生资源来生产。本研究旨在研究从巴西塞拉多生物群落中分离出的两种酵母菌株在生产木糖醇方面的潜力，以及可能影响这一过程的基因组特征。评估了新分离株 Spathaspora sp. JA1 和 Meyerozyma caribbica JA9 对木糖和甘蔗生物质水解液的转化能力，并与对照菌株进行了比较。在所评估的菌株中，Spathaspora sp. JA1 是最强的木糖醇生产菌，在木糖和非解毒水解液上的产物得率和生产强度分别高达 0.74 g/g 和 0.20 g/(L.h)，0.58 g/g 和 0.44 g/(L.h)。获得了 Spathaspora sp. JA1 和 M. caribbica JA9 的基因组序列并进行了注释。比较基因组分析表明，产木糖醇酵母 Spathaspora sp. JA1、M. caribbica JA9 和 Meyerozyma guilliermondii 中的预测木糖代谢途径是保守的，但在高效产乙醇酵母 Spathaspora passalidarum 中则不然。产木糖醇酵母表现出严格依赖 NADPH 的木糖还原酶和依赖 NAD+的木糖醇脱氢酶活性。这种辅酶的不平衡有利于 Spathaspora sp. JA1 表现出高木糖醇得率，这与迄今为止描述的最有效的木糖醇生产菌相似。
