title: High-yield production of lutein by the green microalga Chlorella protothecoides in heterotrophic fed-batch culture.
abstract: The green microalga Chlorella protothecoides was grown heterotrophically in batch mode in a 3.7-L fermenter containing 40 g/L glucose and 3.6 g/L urea. In the late exponential phase, concentrated nutrients containing glucose and urea were fed into the culture, in which the nitrogen source was sufficient compared to carbon source. As a result, a maximum cell dry weight concentration of 48 g/L was achieved. This cell dry weight concentration was 28.4 g/L higher than that obtained in batch culture under the same growth conditions. In another cultivation run, the culture was provided with the same initial concentrations of glucose (40 g/L) and urea (3.6 g/L) as in the batch mode, followed by a relatively reduced supply of nitrogen source in the fed-batch mode to establish a nitrogen-limited culture. Such a modification resulted in an enhanced lutein production without significantly lowering biomass production. The cellular lutein content was 0.27 mg/g higher than that obtained in the N-sufficient culture. The improvements were also reflected by higher maximum lutein yield, lutein productivity, and lutein yield coefficient on glucose. This N-limited fed-batch culture was successfully scaled up from 3.7 L to 30 L, and a three-step cultivation process was developed for the high-yield production of lutein. The maximum cell dry weight concentration (45.8 g/L) achieved in the large fermenter (30 L) was comparable to that in the small one (3.7 L). The maintenance of the culture at a higher temperature (i.e., 32 degrees C) for 84 h resulted in a 19.9% increase in lutein content but a 13.6% decrease in cell dry weight concentration as compared to the fed-batch culture (30 L) without such a treatment. The enhancement of lutein production resulted from the combination of nitrogen limitation and high-temperature stress.
authors.affiliation: Key Laboratory of Microbiology of Agricultural Ministry, Huazhong Agricultural University, Wuhan 430070, P. R. China.
authors.forename: Xian-Ming
authors.initials: XM
authors.lastname: Shi
authors.forename: Yue
authors.initials: Y
authors.lastname: Jiang
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
mesh_terms: D018533:Biomass; D019149:Bioreactors; D002244:Carbon / Q000378:metabolism; D002708:Chlorella / Q000378:metabolism*; D003470:Culture Media; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D014975:Lutein / Q000096:biosynthesis*; D009584:Nitrogen / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D014508:Urea / Q000378:metabolism
chemical_list: D003470:Culture Media; D002244:Carbon; D014508:Urea; D005947:Glucose; D009584:Nitrogen; D014975:Lutein