Utilization of microbial oil produced from Pichia kudriavzevii NCIM 3653 using paper mill sludge as an alternative substrate for biodiesel synthesis

Abstract

This study comprises the production and characterization of biodiesel, synthesized from the microbial oil of oleaginous yeast Pichia kudriavzevii NCIM 3653 which was cultivated using paper mill sludge extract as a substrate. The paper mill sludge subjected to sonication pre-treatment released the highest amounts of carbohydrates and sugars. Optimization of various parameters such as fermentation time and C/N ratio was carried out to increase the lipid yield. Pichia kudriavzevii cultivated in a medium with a C/N ratio of 200 for 120 h gave the highest lipid yield of 2.35 g/L. The effect of the addition of glycerol and yeast extract as additional carbon and nitrogen sources in the medium was studied. The extracted microbial oil was subjected to different analytical techniques such as gas chromatography–mass spectrometry and Fourier transform infrared spectroscopy to test its practicability in biodiesel synthesis. The principal fatty acid methyl esters in the oil were found to be palmitic acid, oleic acid, and stearic acid methyl esters. The percentage of saturated fatty acids in the oil was found to be high, thus indicating its suitability in biodiesel production. The properties of the potential biodiesel complied with the standards laid out by American Society for Testing Materials (ASTM) and European Nations (EN).