Colin Ratledge Center for Microbial Lipids, School of Agricultural Engineering and Food Science, Shandong University of Technology, 266 Xincun West Road, Zibo, 255000, People's Republic of China.
Key Laboratory of Shandong Provincial Universities for Technologies in Functional Agricultural Products, Shandong University of Technology, 266 Xincun West Road, Zibo, 255000, People's Republic of China.
Appl Biochem Biotechnol. 2021 Mar;193(3):856-868. doi: 10.1007/s12010-020-03427-2. Epub 2020 Nov 17.
Previously, we presented a novel approach for increasing the consumption of xylose and the lipid yield by overexpressing the genes coding for xylose isomerase (XI) and xylulokinase (XK) in Mucor circinelloides. In the present study, an in-depth analysis of lipid accumulation by xylose metabolism engineered M. circinelloides strains (namely Mc-XI and Mc-XK) using corn straw hydrolysate was to be explored. The results showed that the fatty acid contents of the engineered M. circinelloides strains were, respectively, increased by 19.8% (in Mc-XI) and 22.3% (in Mc-XK) when compared with the control strain, even though a slightly decreased biomass in these engineered strains was detected. Moreover, the xylose uptake rates of engineered strains in the corn straw hydrolysate were improved significantly by 71.5% (in Mc-XI) and 68.8% (in Mc-XK), respectively, when compared with the control strain. Maybe the increased utilization of xylose led to an increase in lipid synthesis. When the recombinant M. circinelloides strains were cultured in corn straw hydrolysate medium with the carbon-to-nitrogen ratio (C/N ratio) of 50 and initial pH of 6.0, at 30 °C and 500 rpm for 144 h, a total biomass of 12.6-12.9 g/L with a lipid content of 17.2-17.7% (corresponding to a lipid yield of 2.17-2.28 g/L) was achieved. Our study provides a foundation for the further application of the engineered M. circinelloides strains to produce lipid from lignocelluloses.
先前，我们提出了一种通过过表达木糖异构酶 (XI) 和木酮糖激酶 (XK) 基因来提高木糖消耗和脂质产量的新方法，用于粘帚霉。在本研究中，我们深入分析了木糖代谢工程化的粘帚霉菌株（即 Mc-XI 和 Mc-XK）利用玉米秸秆水解物积累脂质的情况。结果表明，与对照菌株相比，工程化的粘帚霉菌株的脂肪酸含量分别增加了 19.8%（在 Mc-XI 中）和 22.3%（在 Mc-XK 中），尽管这些工程化菌株的生物量略有下降。此外，与对照菌株相比，工程化菌株在玉米秸秆水解物中的木糖摄取率分别提高了 71.5%（在 Mc-XI 中）和 68.8%（在 Mc-XK 中）。也许木糖的利用率增加导致脂质合成增加。当重组粘帚霉菌株在碳氮比（C/N 比）为 50、初始 pH 值为 6.0、30°C 和 500 rpm 的条件下，在玉米秸秆水解物培养基中培养 144 小时时，可获得 12.6-12.9 g/L 的总生物量，其中脂质含量为 17.2-17.7%（对应于 2.17-2.28 g/L 的脂质产率）。我们的研究为进一步应用工程化粘帚霉菌株从木质纤维素生产脂质提供了基础。
