Microbial oil production by the oleaginous red yeast, Rhodotorula glutinis NCIM 3168, using corncob hydrolysate

Corncob waste management has become a concern for corn producers worldwide. Agricultural waste-based energy generation is, therefore, extensively researched these days. However, the calorific potential of the moist corncobs still remains untapped due to the lack of technological advancements. In this study, a dilute acid pre-treatment followed with enzymatic hydrolysis was used to recover 80% of the fermentable sugars from the corncobs. When used for microbial oil production in a two-stage fermentation, this enzymatic hydrolysate resulted in a lipid production of more than 75% dried cell weight (DCW) in Rhodotorula glutinis. Extracellular oil capture in this two-stage fermentation further increased the total oil production to 8 g L-1 and 80% DCW. An oleic acid-rich microbial oil profile obtained from this process exhibited excellent biofuel properties. The energy content of the microbial oil valued 40 MJ kg(-1), and was found to be 2.35 times higher than the intrinsic heating capacity of corncobs. Thus, a sustainable bioprocess for corncob waste remediation was devised to obtain vegetable oil equivalent through a microbial conversion platform.