Life Sciences & Biotechnology
Title : | Metabolic engineering of Rhodococcus opacus: A potential workhorse for lignin valorization into high-value lipids |
Area of research : | Life Sciences & Biotechnology |
Focus area : | Metabolic Engineering |
Principal Investigator : | Dr. Senthilkumar Sivaprakasam, Indian Institute Of Technology (IIT) Guwahati, Assam |
Timeline Start Year : | 2023 |
Timeline End Year : | 2026 |
Contact info : | senthilkumar@iitg.ernet.in |
Details
Executive Summary : | Jojoba wax ester (WE), a high-value neutral lipid is gaining traction owing to its multitude of applications viz. an ingredient in almost all cosmetic products; pharmaceutical drug; food additive; wound healer; high-grade lubricant etc. It is a conjugation of C20-C22 very-long-chain fatty acid (VLCFA) and alcohol (VLCFOH). Globally, jojoba WE is extracted from the seeds of a desert shrub Simmondsia chinensis. Despite having versatile applications, the high cost of jojoba WE due to the long harvest time and low yield necessitates uncovering an alternative to meet the demand. The aspect of microbial fermentation surpasses the conventional chemical and immobilized lipase methods. Till now, Saccharomyces cerevisiae and Yarrowia lipolytica are the successful prototypical microbial cell factories for the production of jojoba WE. Attempts were taken to reconstruct the metabolism of Escherichia coli and Acinetobacter baylyi for jojoba WE production; nonetheless, it stored a maximum of ~27% WE of its total dry cell weight (DCW) attaining a chain length of C36. Although yeasts were tailored for jojoba WE production, the economic productivity and product yield are very low making it unsuitable for commercialization. Rhodococcus opacus PD630 is known to be the superior oleaginous accumulating ~80% triacylglycerol (TAG) of its DCW. Although it is a sole TAG producer, it was reported to produce minute quantities of WE upon the cultivation of hydrocarbons. Expression of fatty acyl CoA reductase (far), a gene responsible for FOH conversion revamped R. opacus to accumulate 45% of WE of its total lipids (WE+TAG). Even though bacteria can accumulate WEs, the rationale behind leveraging yeasts for jojoba WE production is that the fatty acid elongation (FAE) responsible for the production of VLCFA occurs at the endoplasmic reticulum (ER). Contrastingly, the pathogenic Mycobacterium tuberculosis is well-known for producing VLCFA defining the existence and potential of the cytosolic FAE system. Here, we propose R. opacus for the production of jojoba WE owing to the endowment of highly similar fatty acid synthase (FAS) to M. tuberculosis and reported to produce VLCFA of C54 for mycolic acid synthesis. Moreover, R. opacus is a potential chassis for lignin valorization owing to its innate catabolism, tolerance and adaptive evolution on various hydrocarbons. Literature reports failed to address the most critical issue of precursor imbalance, the main reason for the reduced WE titer. For the first time, we have proposed a dynamic control strategy based on negative-layered metabolic loop (NLML) to resolve the precursor imbalance and hence achieve enhanced jojoba WE yield. Considering the incredible metabolism of R. opacus and the major interest of biorefineries to produce biochemicals from by-products, we hypothesized an integrated bioprocess approach for the sustainable valorization of black liquor into jojoba WE by a metabolically engineered R. opacus. |
Co-PI: | Dr. Selvaraju Narayanasamy, Indian Institute Of Technology (IIT) Guwahati, Assam-781039 |
Total Budget (INR): | 58,96,264 |
Organizations involved