Biodiesel production from heterotrophic oleaginous microalga Thraustochytrium sp. BM2 with enhanced lipid accumulation using crude glycerol as alternative carbon source.

Aiming to improve the economy and sustainability of biodiesel production, the scale-up of lipid production by heterotrophic Thraustochytrium sp. BM2 utilizing crude glycerol as a low cost carbon source was optimized in stirred tank fermenter. The issues of impurities such as excess ions, methanol, soap and other organic impurities as well as different pretreatment techniques were explored and tackled for industrial application of crude glycerol as carbon source. For process engineering strategies to enhance lipid production, semi-batch operation outperformed fed-batch cultivation and achieved higher lipid yield and overall lipid productivity primarily due to shorter fermentation time. The two-step esterification/transesterification method achieved high fatty acid methyl ester (FAME) conversion rate up to 91.8%, which was two to three folds higher compared with the one-step process.