title: High-cell-density fermentation for ergosterol production by Saccharomyces cerevisiae.
abstract: The direct feedback control of glucose using an on-line ethanol concentration monitor for ergosterol production by high-cell-density fermentation was investigated and the fermentation parameters (e.g., pH, dissolved oxygen, ethanol concentration, oxygen uptake rate, carbon dioxide evolution rate and respiratory quotient) were analyzed. Controlling glucose feeding rate in accordance with ethanol concentration and adjusting pH with ammonia during the fermentation process were effective fed-batch methods for ergosterol production. The fermentation parameters well described the variation of the whole fermentation process. Cultivation in a 5 l fermentor was carried out under the following conditions: culture temperature, 30 degrees C; pH, 5.5; agitation speed, 600 rpm; fermentation time, 60 h; controlling ethanol concentration below 1% and keeping respiratory quotient (RQ) at approximately 1.0. Under these conditions, the yeast dry weight reached 120 g/l and the ergosterol yield reached 1500 mg/l.
authors.affiliation: Beijing Key Lab of Bioprocess, College of Biology Science and Technology, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Shang
authors.forename: Shaohong
authors.initials: S
authors.lastname: Wen
authors.forename: Xi
authors.initials: X
authors.lastname: Wang
authors.forename: Tianwei
authors.initials: T
authors.lastname: Tan
mesh_terms: D019149:Bioreactors / Q000382:microbiology; D004875:Ergosterol / Q000096:biosynthesis*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology / Q000379:methods*; D010100:Oxygen / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005947:Glucose; D010100:Oxygen; D004875:Ergosterol