Geijer Cecilia, Faria-Oliveira Fábio, Moreno Antonio D, Stenberg Simon, Mazurkewich Scott, Olsson Lisbeth
1Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.
2Present Address: Biofuels Unit, Department of Energy, CIEMAT, Madrid, Spain.
Biotechnol Biofuels. 2020 Mar 12;13:48. doi: 10.1186/s13068-020-1663-9. eCollection 2020.
An economically viable production of biofuels and biochemicals from lignocellulose requires microorganisms that can readily convert both the cellulosic and hemicellulosic fractions into product. The yeast displays a high capacity for uptake and conversion of several lignocellulosic sugars including the abundant pentose d-xylose, an underutilized carbon source since most industrially relevant microorganisms cannot naturally ferment it. Thus, constitutes an important source of knowledge and genetic information that could be transferred to industrial microorganisms such as to improve their capacity to ferment lignocellulose-derived xylose.
To understand the genetic determinants that underlie the metabolic properties of , we sequenced the genomes of both the in-house-isolated strain CBS 141442 and the reference strain PYCC 4715. De novo genome assembly and subsequent analysis revealed to be a haploid species belonging to the CTG clade of yeasts. The two strains have highly similar genome sizes and number of protein-encoding genes, but they differ on the chromosomal level due to numerous translocations of large and small genomic segments. The transcriptional profiles for CBS 141442 grown in medium with either high or low concentrations of glucose and xylose were determined through RNA-sequencing analysis, revealing distinct clusters of co-regulated genes in response to different specific growth rates, carbon sources and osmotic stress. Analysis of the genomic and transcriptomic data also identified multiple xylose reductases, one of which displayed dual NADH/NADPH co-factor specificity that likely plays an important role for co-factor recycling during xylose fermentation.
In the present study, we performed the first genomic and transcriptomic analysis of and identified several novel genes for conversion of xylose. Together the results provide insights into the mechanisms underlying saccharide utilization in and reveal potential target genes to aid in xylose fermentation in .
从木质纤维素经济可行地生产生物燃料和生物化学品需要能够将纤维素和半纤维素部分都容易地转化为产品的微生物。该酵母对几种木质纤维素糖具有高摄取和转化能力，包括丰富的戊糖D-木糖，这是一种未充分利用的碳源，因为大多数工业相关微生物不能自然发酵它。因此，该酵母构成了知识和遗传信息的重要来源，可转移到工业微生物如酿酒酵母中，以提高其发酵木质纤维素衍生木糖的能力。
为了了解该酵母代谢特性背后的遗传决定因素，我们对内部分离菌株CBS 141442和参考菌株PYCC 4715的基因组进行了测序。从头基因组组装和后续分析表明该酵母是属于酵母CTG进化枝的单倍体物种。这两个菌株具有高度相似的基因组大小和蛋白质编码基因数量，但由于大小基因组片段的大量易位，它们在染色体水平上有所不同。通过RNA测序分析确定了在高浓度或低浓度葡萄糖和木糖培养基中生长的CBS 141442的转录谱，揭示了响应不同特定生长速率、碳源和渗透胁迫的共调控基因的不同簇。对基因组和转录组数据的分析还鉴定了多种木糖还原酶，其中一种显示出双重NADH/NADPH辅因子特异性，这可能在木糖发酵过程中的辅因子循环中起重要作用。
在本研究中，我们对该酵母进行了首次基因组和转录组分析，并鉴定了几个用于木糖转化的新基因。这些结果共同提供了对该酵母中糖类利用机制的见解，并揭示了有助于该酵母中木糖发酵的潜在靶基因。
