title: Kinetics of asparaginase II fermentation in Saccharomyces cerevisiae ure2dal80 mutant: effect of nitrogen nutrition and pH.
abstract: Although the quality of nitrogen source affects fermentation product formation, it has been managed empirically, to a large extent, in industrial scale. Laboratory-scale experiments successfully use the high-cost proline as a nonrepressive source. We evaluated urea as a substitute for proline in Saccharomyces cerevisiae ure2dal80 fermentations for asparaginase II production as a model system for nitrogen-regulated external enzymes. Maximum asparaginase II levels of 265 IU/L were observed in early stationary-phase cells grown on either proline or urea, whereas in ammonium cells, the maximum enzyme level was 157 IU/L. In all cases, enzyme stability was higher in buffered cultures with an initial pH of 6.5.
authors.affiliation: Far-Manguinhos, FIOCRUZ, Av. Sizenando Nabuco, 100, 21041-250, Rio de Janeiro, RJ, Brazil. ferrara@far.fiocruz.br
authors.forename: Maria Antonieta
authors.initials: MA
authors.lastname: Ferrara
authors.forename: Josiane M V
authors.initials: JM
authors.lastname: Mattoso
authors.forename: Elba P S
authors.initials: EP
authors.lastname: Bon
authors.forename: Nei
authors.initials: N
authors.lastname: Pereira
mesh_terms: D001215:Asparaginase / Q000737:chemistry* / Q000235:genetics; D001709:Biotechnology / Q000379:methods*; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009154:Mutation; D009584:Nitrogen / Q000737:chemistry; D011392:Proline / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D013997:Time Factors; D014508:Urea / Q000737:chemistry
chemical_list: D000644:Quaternary Ammonium Compounds; D014508:Urea; D011392:Proline; D001215:Asparaginase; D009584:Nitrogen