title: [Biomass production enriched in intracellular methionine by a mutant of Saccharomyces cerevisiae].
abstract: According with FAO reported data the methionine intracellular content in Saccharomyces cerevisiae is higher than another yeast. For increasing the yeast methionine internal concentration three S. cerevisiae mutant strains were chosen (M2, M4 y M9), obtained by ethionine (0.1 mg/ml) and norleucine (0.33 mg/ml) resistance by González Miliani (personal communication). The resistance levels in culture were modified until selection of a mutant LF-M9 etr norr, which shows resistance to ethionine (6 mg/ml). Optimal conditions for growth were fixed on shaked flasks and later mutationaly experiments were conducted with nitrosoguanidine (0.5 mg/ml) and U.V. light (240 nm in 9 minutes d = 32 cm). Mutants obtained were selected on plate replicates and microbiological test, using Escherichia coli 303 (Wollman, met- b1- strr) as the indicating strain. The mutant LF-M9 treo- etr norr, shows an intracellular methionine content 3 times higher than the control strain DSM D273-10B and 1.8 times higher than parental strain M9. The mutant was cultivated on different agroindustrial wastes and the optimal growth was reached in acid hydrolysates of cassava foliage. Fermentations in 1 litre stirred fermentor were accomplished using these medium and the biomass obtained was 6.3 g of the yeast (dry weight) enriched in methionine per litre of extract.
mesh_terms: D018533:Biomass; D003470:Culture Media; D008715:Methionine / Q000378:metabolism*; D009154:Mutation; D009604:Nitrosoguanidines / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D003470:Culture Media; D009604:Nitrosoguanidines; D008715:Methionine
vernacular_title: Producción de biomasa enriquecida en metionina intracelular por un mutante de Saccharomyces cerevisiae.