To be or not to be” an oleaginous bacterium! What are the mechanisms involved?

ALVAREZ HM

Buenos Aires

Congreso; XVII Reunión Anual de la Sociedad Argentina de Microbiología General (SAMIGE,); 2022

SAMIGE

Triacylglycerol (TAG) accumulation is a common feature among rhodococci. Some members of this genus are able to accumulate significant amounts of TAG (more than 50% of CDW), such as Rhodococcus opacus PD630 and R. jostii RHA1, thus, they can be considered as oleaginous bacteria. These microorganisms have been considered as alternative sources of single-cell oils with potential applications in the industry, or for the conversion of industrial wastes into precursor oils for biofuels, biolubricants and oleochemicals, among other products. In general, oleagenicity might be based on the ability of cell to produce a continuous supply of acetyl-CoA and sufficient NADPH, as the necessary precursor and reductants for fatty acid biosynthesis. The TAG biosynthetic machinery of oleaginous rhodococci may include enzymes involved in different reactions of metabolism, transporter proteins, structural components of lipid inclusions, and transcriptional regulators at different hierarchical levels (global and local regulators). However, the difference between oleaginous and non-oleaginous bacteria is not simply the presence/absence of key genes/enzymes related to lipid synthesis. Recent studies demonstrated that oleagenicity is a finely regulated multilayer process in rhodococci. It demands the existence of mechanisms that synergistically integrate the individual contribution of genes generating a strong flux of available C through lipid metabolism. Lipogenesis seems to be a finely regulated process including many layers of transcriptional, post-transcriptional and allosteric control in rhodococcal cells. Our current efforts attempt to understand the physiological and molecular basis of the lipogenesis and oleagenicity in rhodococci, and to decipher the metabolic and regulatory mechanisms involved in the hyper-lipid production. Recent advances have allowed us to find some metabolic and regulatory innovations in oleaginous bacteria of the genus Rhodococcus that improve our understanding of the factors that have contributed to the natural design and specialization of hyper-lipid-producing species.