Enhancing oil accumulation of a mixed culture of Chlorella sp and Saccharomyces cerevisiae using fish waste hydrolysate

Mixed culture of Chlorella sp. and Saccharomyces cerevisiae using fish waste hydrolysate has been proposed as a novel strategy for enhancing oil formation in this study. Fish waste hydrolysate (FWH) concentration ranging from 1.1 to 8.8 g/l of the mixed culture was investigated, the optimal biomass concentration reached 3626 mg/l at 4.4g/l FWH, however, the maximum oil concentration was obtained as 1219 mg/l at 8.8 g/l FWH. Results indicated biomass and oil content of the mixed culture in mixotrophic cultivation with FWH medium was better than those in heterotrophic cultivation and mixotrophic cultivation with a rich complex medium. Organic acid supplementation to the mixed culture was performed to explain the mechanism of oil accumulation in the mixed culture. Butyric acid significantly enhanced biomass formation by 20% and oil accumulation by 143% under mixotrophic cultivation. The calculated cetane numbers of oils based on the fatty acid analysis from mixed culture and Chlorella sp. monoculture were 61.79 and 61.46, respectively, and they all complied with the European standard for biodiesel. FWH medium is a potential alternative for economic biodiesel production. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.