ABSTRACT
This work focuses on the lime pretreatment of rice straw, agricultural waste in northeast Vietnam, for microbial lipid (bio-lipid) production. A response surface methodology approach was performed to optimize parameters for the pretreatment process. These parameters are the concentration of Ca(OH)2, hydrolysis temperature, and maintained time; the effect is considered bio-lipid production yield. The lipid yield was estimated through consolidated bioprocessing of the pretreated rice straw as a substrate and using the fungus strain (Aspergillus oryzae 32) and the yeast strain (Lipomyces starkeyi 22). As a result, the optimal pretreatment conditions for maximum lipid yield were obtained at Ca(OH)2 concentration of 12 g/L and hydrolysis temperature of 110 °C within 60 min. The accumulated lipid in fermentation using these oleaginous microorganisms was 8.5g/100g oven-dry weight of rice straw (10.9g/100g for pretreated rice straw). The biolipid consisted of 42.6% saturated, 21.1% monounsaturated (MUFA), and 35.1% polyunsaturated (PUFA) fatty acids.
