title: Mixotrophic continuous flow cultivation of Chlorella protothecoides for lipids.
abstract: The oleaginous alga Chlorella protothecoides accumulates lipid in its biomass when grown in nitrogen-restricted conditions. To assess the relationship between nitrogen provision and lipid accumulation and to determine the contribution of photosynthesis in mixotrophic growth, C. protothecoides was grown in mixo- and heterotrophic nitrogen-limited continuous flow cultures. Lipid content increased with decreasing C/N, while biomass yield on glucose was not affected. Continuous production of high lipid levels (57% of biomass) was possible at high C/N (87-94). However, the lipid production rate (2.48 g L(-1) d(-1)) was higher at D=0.84 d(-1) with C/N 37 than at D=0.44 d(-1) and C/N 87 even though the lipid content of the biomass was lower (38%). Photosynthesis contributed to biomass and lipid production in mixotrophic conditions, resulting in 13-38% reduction in CO2 production compared with heterotrophic cultures, demonstrating that photo- and heterotrophic growth occurred simultaneously in the same population.
authors.affiliation: VTT Technical Research Centre of Finland, VTT, Espoo, Finland.
authors.forename: Yanming
authors.initials: Y
authors.lastname: Wang
authors.forename: Heiko
authors.initials: H
authors.lastname: Rischer
authors.forename: Niels T
authors.initials: NT
authors.lastname: Eriksen
authors.forename: Marilyn G
authors.initials: MG
authors.lastname: Wiebe
mesh_terms: D061249:Batch Cell Culture Techniques; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods*; D002708:Chlorella / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D052836:Heterotrophic Processes / Q000187:drug effects; D008055:Lipids / Q000096:biosynthesis*; D009584:Nitrogen / Q000172:deficiency / Q000494:pharmacology; D012212:Rheology
chemical_list: D008055:Lipids; D002245:Carbon Dioxide; D002244:Carbon; D005947:Glucose; D009584:Nitrogen
keywords: Biomass concentration (g dry biomass per L); C/N; C/N ratio; CER; Carbon dioxide evolution rate (molL(−1) d(−1)); Continuous flow culture; D; DOT; Dilution rate (d(−1)); Dissolved oxygen tension (% air saturation); Lipid; Maximum specific growth rate (d(−1)); Microalgae; Mixotrophic growth; OUR; Oxygen uptake rate (molL(−1)d(−1)); Ratio of organic carbon and nitrogen (molmol(−1)); Volumetric biomass production rate (gL(−1)d(−1)); Volumetric lipid production rate (gL(−1)d(−1)); Y(CO2/Glu); Y(Lip/Glu); Y(x/Glu); Yield of CO(2) on glucose (mol of CO(2) generated per C-mol of glucose consumed); Yield of biomass on glucose (g of biomass per g of glucose consumed); Yield of lipids on glucose (g of lipids per g of glucose consumed); r(Lip); r(x); x; μ(max)