The effect of nutrition pattern alteration on Chlorella pyrenoidosa growth, lipid biosynthesis-related gene transcription

•Chlorella accumulate considerable lipid during heterotrophic to autotrophic transition.•Lipid and protein contents increased rapidly along with the sharp decline of starch.•Isogenes encoding ME, PEPC and DGAT are related to lipid accumulation.•These genes might be exploited as target genes for genetic modification.•The switch strategy could be developed for efficient algal lipid production. Heterotrophy to photoautotrophy transition leads to the accumulation of lipids in Chlorella, which has potential to produce both healthy food and biofuels. Therefore, it is of key interest to study the metabolism shift and gene expression changes that influenced by the transition. Both total and neutral lipids contents were increased rapidly within 48h after the switch to light environment, from 24.5% and 18.0% to 35.3% and 27.4%, respectively, along with the sharp decline of starch from 42.3% to 10.4% during 24h photoinduction phase. By analyzing the correlation between lipid content and gene expression, results revealed several genes viz. me g3137, me g6562, pepc g6833, dgat g3280 and dgat g7566, which encode corresponding enzymes in the de novo lipid biosynthesis pathway, are highly related to lipid accumulation and might be exploited as target genes for genetic modification. These results represented the feasibility of lipid production through trophic converting cultivation.