(752d) Modeling and Optimization for Efficient Production of Lipids By Oleaginous Yeast Rhodotorula Glutinis Cultivated in Pulp and Paper Wastewater

Oleaginous microorganisms have become known as potential sources of lipids to be used as biodiesel feedstock. It has been shown that oleaginous yeast Rhodotorula glutinis is able to grow and accumulate lipids in amended pulp and paper wastewater.  Response surface methodology (RSM) with a Box–Behnken design with total of four variables and 3-levels of variables was used in design optimization to predict the best value of the lipid production. The effects of initial glucose concentration, initial nitrogen concentration, initial inoculum concentration, and fermentation time on the lipid production were evaluated. Various initial sugar (40-80 g/L) and nitrogen (0.6-1.4 g/L) concentrations resulting in various C/N (50-250) ratios were investigated. The experiments were conducted in 1L Erlenmeyer flasks. The pH was adjusted to 6.5 prior to the experiments, and the seed culture levels of 10-20% (v/v) was used as inoculum culture to 200 ml medium and incubated at 30 °C in a rotary shaker with shaking speed of 120 rpm for 5-9 days. The synergy between four independent variables is determined with respect to their effects on the lipid production. A detailed mathematical model was used to describe the behavior of oleaginous microorganisms in pulp and paper wastewater. The suggested model was able to adequately predict biomass growth, lipid accumulation, and sugar utilization by oleaginous yeast while cultivated under nitrogen limited condition. The model kinetic parameters for biomass, sugar consumption, and lipid accumulation of Rhodotorula glutinisfrom augmented pulp and paper wastewater were estimated. The model could be applied to similar systems of lipid production and become a useful implement for design of bioreactors for large scale biodiesel production.