Abstract

TWO STAGE FED BATCH STRATEGY FOR ENHANCED LIPID PRODUCTION BY OLEAGINOUS YEAST

Ashok Kumar Yadav and Arindam Kuila*

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Abstract

Biodiesel is known for its lower GHG emissions and closed carbon cycle, these are the reasons why the impact of this renewable energy source on global warming is lower than fossil fuels. Oleaginous yeasts have high lipid content, volumetric productivity, and also grows fast, which declares them the favourable substitute to biodiesel production. Lignocellulosic biomass is abundantly accessible in the living world and has sustainable characteristics which makes it more economical than other substrates. In order to minimize the environmental pollution and the cost of production of lipids, oleaginous microorganisms are cultivated using low cost substrate like lignocellulosic biomass. To enhance the lipids production, two-stage fed-batch cultivation had been applied using Cladosporium iridis strain CBS 138.40. Carbon source in combination with fed-batch fermentation were tried out strategically to enhance the lipid content. In this study the engrossed strategy was two stages fed-batch strategy for increased lipid production. Biodiesel was produced by trans-esterifying the produced lipid using lipase. The pH of the feeding solutions was 6.1 and consisted of 0.4 g/L KH2PO4, 2.0 g/L MgSO4·7H2O, and crude glycerol. The concentration of crude glycerol helped to enhance the growth and lipid accumulation of Cladosporium iridis strain CBS 138.40, with 15.9 ± 0.1 g/L of cell mass concentration. The fungi were cultivated in glycerol, when the rates of glycerol was brought down to low, a lipid turnover was detected in Zygomycetes fungi. Crude glycerol plays an important role in the lipid accumulation and growth oleaginous microorganisms (OMs) which leads to reserved cell metabolic activities and excessive osmotic stress.

Keywords: Biodiesel, Oleaginous yeast, Transesterification, Biodiesel characterization.