Anthony Winston E, Geng Weitao, Diao Jinjin, Carr Rhiannon R, Wang Bin, Ning Jie, Moon Tae Seok, Dantas Gautam, Zhang Fuzhong
The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA.
Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA.
Biotechnol Biofuels Bioprod. 2024 Jun 19;17(1):83. doi: 10.1186/s13068-024-02523-3.
Lignocellulosic biomass is currently underutilized, but it offers promise as a resource for the generation of commercial end-products, such as biofuels, detergents, and other oleochemicals. Rhodococcus opacus PD630 is an oleaginous, Gram-positive bacterium with an exceptional ability to utilize recalcitrant aromatic lignin breakdown products to produce lipid molecules such as triacylglycerols (TAGs), which are an important biofuel precursor. Lipid carbon storage molecules accumulate only under growth-limiting low nitrogen conditions, representing a significant challenge toward using bacterial biorefineries for fuel precursor production. In this work, we screened overexpression of 27 native transcriptional regulators for their abilities to improve lipid accumulation under nitrogen-rich conditions, resulting in three strains that accumulate increased lipids, unconstrained by nitrogen availability when grown in phenol or glucose. Transcriptomic analyses revealed that the best strain (#13) enhanced FA production via activation of the β-ketoadipate pathway. Gene deletion experiments confirm that lipid accumulation in nitrogen-replete conditions requires reprogramming of phenylalanine metabolism. By generating mutants decoupling carbon storage from low nitrogen environments, we move closer toward optimizing R. opacus for efficient bioproduction on lignocellulosic biomass.
木质纤维素生物质目前未得到充分利用,但它有望成为生产商业终端产品的资源,如生物燃料、洗涤剂和其他油脂化学品。食油红球菌PD630是一种产油的革兰氏阳性细菌,具有利用难降解的芳香族木质素分解产物生产脂质分子(如三酰甘油(TAGs))的特殊能力,而三酰甘油是一种重要的生物燃料前体。脂质碳储存分子仅在生长受限的低氮条件下积累,这对利用细菌生物精炼厂生产燃料前体构成了重大挑战。在这项工作中,我们筛选了27种天然转录调节因子的过表达情况,以评估它们在富氮条件下改善脂质积累的能力,从而获得了三株在苯酚或葡萄糖中生长时不受氮可用性限制、脂质积累增加的菌株。转录组分析表明,最佳菌株(#13)通过激活β-酮己二酸途径提高了脂肪酸的产量。基因缺失实验证实,在氮充足的条件下脂质积累需要对苯丙氨酸代谢进行重新编程。通过生成使碳储存与低氮环境脱钩的突变体,我们朝着优化食油红球菌以高效利用木质纤维素生物质进行生物生产的目标又迈进了一步。