Conversion of waste and nontraditional carbon sources for lipid production by Rhodococcus rhodochrous

Oleaginous microbes can accumulate over 20% of their cell dry weight as lipids that are stored as intracellular energy reserves. The characterization of other oleaginous bacteria creates opportunities for the development of alternative feedstocks and technologies. Rhodococcus rhodochrous is a gram-positive bacterium known for its biodegradation capabilities and was recently determined to be oleaginous when grown in glucose-supplemented media. As R. rhodochrous is capable of degrading hydrocarbon gasses and other aromatics, we aim to investigate any associated lipid production during the conversion of waste and nontraditional carbon sources. Shake flask and larger scale fermenter experiments were used to culture R. rhodochrous with various carbon sources, including phenol, vanillic acid, hydroxybenzoic acid, and propane. The results suggest that R. rhodochrous can survive in the presence of these compounds, achieving almost 7g/L cell dry weight after 168 hours and still accumulate up to 40-50% of cell dry weight as lipid in glucose supplemented media. Furthermore, the aromatic compounds are undetected after 48 hours. Fatty acid methyl ester profiles show a prevalence of palmitic and oleic methyl esters. Overall, our studies are contributing to a better understanding and characterization of another oleaginous Rhodococcus species, Rhodococcus rhodochrous.