Influence of Nitrogen on Lipid and Biomass Production by Oleaginous Yeast Cultures

This study was undertaken to investigate the influence of nitrogen sources on lipid production by different yeast cultures. Among the four nitrogen sources, yeast extract and peptone showed maximum lipid production in biomass (22.85 and 20.03 per cent, respectively) and they were at par with each other, while ammonium sulphate (16.70 per cent) and sodium nitrate (13.34 per cent) exhibited poor lipid accumulation. Yeast extract containing broth supported to produce maximum lipid in Rhodotorula glutinis (23.82 per cent), followed by Rhodosporidium toruloides (22.53 per cent) and Lipomyces starkeyi (22.21 per cent). High amount of biomass as 10.20, 10.16 and 10.14 g l^-1 was also observed using yeast extract as nitrogen source, respectively of the above cultures. Further experiment on optimization of the concentrations ranging from 0.5 to 1.75 per cent revealed the production of higher lipids was under 0.75 per cent. Among the various concentrations evaluated, maximum lipid and biomass production was observed in Rhodotorula glutinis (31.3 per cent and 11.5 g l^-1), Rhodosporidium toruloides (29.72 per cent and 11.10 g l^-1) and Lipomyces starkeyi (28.50 per cent and 11.05 g l^-1), respectively at 0.75 per cent level. Reduction in biomass as well as lipid yield was observed when increase in concentrations of yeast extract beyond 1.0 per cent.