Isolation and identification of lipid-producing microalgae and effect of different trophic modes on its oil accumulation

he freshwater microalga, strain C67, was isolated from a freshwater lakein Hainan and selected as ahigh lipid producer. The biomass productivity and lipid content of the microalgal strain were analyzed under different trophic cultivation modes including autophototrophic, mixotrophic and heterotrophic cultivations. The strain was tentatively identified as Micractinium reisseri C67 based on microscopic examination and Lsu (large subunit) rDNA sequence analysis. Major fatty acids in the microalgae were C18:1, C16:0, C18:3 and C18:2, comprising 33%, 26%, 18% and 11% of the total fatty acids, respectively. The biomass productivity and lipid content of M.reisseri C67 under mixotrophic cultivation were higher than those of under autotrophic and heterotrophic cultivations. The maximum biomass productivity (7.0 gL-1) and the maximum lipid content (40.2%) of M.reisseri C67 were achieved under mixotrophic cultivation with glucose and glycine (Gly), respectively. The lipid productivity of M.reisseri C67 was 2.2 gL-1,7.3 and 7.9 folds of those obtained under autophototrophic and heterotrophic conditions, respectively.