Development of nutrient media to increase the accumulation of lipids without genetic modification of a lipogenic microorganism

Abstract

Yarrowia lipolytica has drawn attention from the scientists over the last few decades because of its potential to accumulate intracellular lipid that can be transesterified to methyl esters with properties resembling those of diesel. A kinetics study of intracellular lipid production in Y. lipolytica is very important because it would help process modeling and cost minimization for increasing the lipid production. A set of defined media with varying amounts of pure glycerol as the carbon source and a fixed amount of ammonium sulfate as the nitrogen source and other media components, including thiamine and uracil supplements, was used to study the kinetics of lipid production. With an increase in the carbon to nitrogen (C/N) ratio, lipid accumulation increased to a certain limit up to 4 g L⁻¹, followed by substrate inhibition. The best rate and amount of lipid accumulation was predicted to be obtained in a cultivation medium with an initial glycerol concentration of 93 g L⁻¹. While lipid production was high, citric acid production in the media was negligible. Minimization of citric acid synthesis via proper media development with nitrogen starvation and unique supplement utilization can increase lipid accumulation in Y. lipolytica IMUFRJ 50682 up to a great extent in mere batch cultivation without any genetic modification.