Production of ribonucleotides by autolysis of Pichia anomala mutant and some physiological activities.

Various mutants of Pichia anomala were isolated by ethyl methanesulfonate (EMS) treatment and UV irradiation through cycloheximide resistance and KC1 sensitivity. The selected mutant HA-2 accumulated a higher content of RNA and grew faster than the wild-type strain in yeast extract-malt (YM) broth. Autolysis of the HA-2 mutant at 60 °C and pH 7.0 for 6 h was the best condition to obtain maximum yields of 5 `-ribonucleotides, inosinic monophosphate (IMP) (6.2 mg/g biomass) and guanylic monophosphate (GMP) (35.5 mg/g biomass). The yield of adenylic monophosphate (AMP) (7.8 mg/g biomass) was optimal at 60 °C at pH 6.5 for 6 h. The inhibitory activity of the angiotensin-converting enzyme and the nitrite-scavenging activity for autolysates of the HA-2 mutant were about 13.0% and 47.0% higher than those of native strain, respectively. [ABSTRACT FROM AUTHOR]

Divers mutants de Pichia anomala ont été isolé par le traitement au methanesulfonate d'éthyle (EMS) et à l'irradiation aux UV gr&acric;ce à la résistance au cycloheximide et à la sensibilité au KCI. Le mutant selectionné HA-2 accumulait un plus haut contenu d'ARN et sa croissance était plus rapide que la souche sauvage dans le milieu YM. L'autolyse du mutant HA-2 à 60 °C, pH 7.0 durant 6 h a été retenue pour maximiser les rendements de 5' -ribonucleotides, d'IMP (6.2 mg/g biomasse) et de GMP (35.5 mg/g biomasse). Le rendement d'AMP (7.8 mg/g biomasse) était optimal pour 6 h d'incubation à 60 °C, pH 6.5. L'activité inhibitrice de la conversion enzymatique de l'angiotensine et l'activité d'enlèvement du nitrite dans les autolysats du mutant HA-2 étaient respectivement de 13.0% et 47.0% plus élevées que ceux de la souche sauvage. [ABSTRACT FROM AUTHOR]

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