Puseenam Aekkachai, Tanapongpipat Sutipa, Roongsawang Niran
Microbial Cell Factory Laboratory, Bioresources Technology Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand.
Appl Biochem Biotechnol. 2015 Dec;177(8):1690-700. doi: 10.1007/s12010-015-1846-1. Epub 2015 Sep 16.
Scheffersomyces stipitis strain BCC15191 is considered as a biotechnologically valuable yeast for its ability to ferment glucose and xylose, the main sugar components in plant biomass, to ethanol. However, the wild strain lacks of endogenous cellulases and hemicellulases that limited biomass utilization. In order to improve biomass degrading ability of S. stipitis BCC15191, new integrative plasmids harboring constitutive TEF1 promoter and codon-optimized zeocin or hygromycin antibiotic resistance genes were developed. Aspergillus niger endoxylanase and Aspergillus aculeatus endoglucanase activities were demonstrated in transformant cells expressing codon-optimized genes. S. stipitis co-expressing endoxylanase and endoglucanase was able to grow in medium containing xylan and β-glucan as carbon sources and directly produced ethanol with yields of 2.7 g/L. It could also use pretreated corncob as a carbon source for ethanol production. These results suggested that recombinant S. stipilis is possible for consolidated bioprocessing of biomass.
树干毕赤酵母菌株BCC15191因其能够将植物生物质中的主要糖分葡萄糖和木糖发酵成乙醇，而被认为是一种具有生物技术价值的酵母。然而，野生菌株缺乏内源性纤维素酶和半纤维素酶，这限制了生物质的利用。为了提高树干毕赤酵母BCC15191的生物质降解能力，开发了携带组成型TEF1启动子和密码子优化的博来霉素或潮霉素抗生素抗性基因的新型整合质粒。在表达密码子优化基因的转化细胞中证实了黑曲霉内切木聚糖酶和棘孢曲霉内切葡聚糖酶的活性。共表达内切木聚糖酶和内切葡聚糖酶的树干毕赤酵母能够在以木聚糖和β-葡聚糖作为碳源的培养基中生长，并直接生产乙醇，产量为2.7 g/L。它还可以使用预处理的玉米芯作为乙醇生产的碳源。这些结果表明，重组树干毕赤酵母对于生物质的联合生物加工是可行的。
