Optimization of Culture Conditions for Biomass and Lipid Production by Oleaginous Fungus Penicillium Citrinum PKB20 Using Response Surface Methodology (RSM)

Penicillium citrinum is a naturally occurring filamentous fungus with immense potential for biomass-based diesel production because they are prolific producers of cellulose-degrading enzymes and also accumulate significant amount of lipids. In this study, four media components, namely, carbon source, nitrogen (organic and inorganic) source and metal salts, and three fermentation parameters viz. Incubation time, temperature and pH were first screened for their effect on the biomass and lipid production by P. citrinum PKB20 using 'one variable at a time' (OVAT) approach. OVAT based experiments revealed that glucose (X-G), yeast extract (X-Y), ammonium sulphate (X-A) and magnesium ion (X-M) had the greatest impact on biomass yield and lipid accumulation when grown under batch cultivation mode at pH 7, temperature 30 degrees C and incubation time of 6 days. A central composite design based response surface methodology (RSM) was then adopted to model and optimize the ideal concentrations of the media constituents for maximum production of biomass and lipid from oleaginous fungus Penicillium citrinum PKB20.The optimization condition was found to be 10% of X-G, 0.75 g/L of X-Y, 0.38 g/L of X-A and 0.06 g/L of XM and under optimum condition, the biomass and lipid production was 7.9 g/L and 1.73 g/L respectively. The study thus presents the optimum concentrations of key media components and culture conditions for maximum biomass and lipid production by Penicillium citrinum PKB20 under the studied cultivation and harvesting conditions.