RESUMO
The production of penicillin G and penicillin V amidohydrolases or acylases (E.C.3.5.1.11) was studied during the autolysis of filamentous fungi in a mineral medium, and in the same medium with phenoxyacetic acid as inducer. In all the studied fungi, enzymes showing penicillin G and penicillin V amidohydrolase activities were found. Generally, an increase of these activities during fungal autolysis was observed. The presence of phenoxyacetic acid in the medium did not increase these activities. The activities found in the culture fluids were generally higher than that found in the mycelial extracts. Under these conditions, beta-lactamases (penicillinases) were not found. The fungi Alternaria alternata, Fusarium culmorum, Penicillium oxalicum, and the species Penicillium 222 were chosen to study penicillin G and penicillin V acylases. The enzymes were precipitated with tannic acid from the culture fluid of their autolyzed cultures. Some kinetic constants of these activities were determined.
Assuntos
Amidoidrolases/biossíntese , Fungos Mitospóricos/enzimologia , Mucorales/enzimologia , Penicilina Amidase/biossíntese , Autólise/enzimologia , Autólise/microbiologia , Penicilina G/metabolismo , Penicilina V/metabolismo , Especificidade da EspécieRESUMO
The kinetics of the autolytic phase of growth in cultures of Aspergillus niger has been studied. Two different autolytic periods could be distinguished. One, consisting of a rapid (exponential) loss (62%) of mycelial weight, occurred between 36 and 117 hours of incubation. A second, consisting of a slow autolysis, occurred between the 117th and the 190th hour of incubation; the mycelial loss here being 5%. Based on the degree of autolysis (alpha = 67.0%), 92.5% and 7.5% are lost during the first and the second autolytic periods, respectively.
Assuntos
Aspergillus niger/crescimento & desenvolvimento , Autólise , Aspergillus niger/metabolismo , CinéticaRESUMO
The induced autolysis of Aspergillus niger was studied by suspending mycelia in water; after 120 hours there was a 50% reduction in dry weight. The kinetics of the liberation of electrolytes during autolysis was studied, and a positive correlation was observed between the electrical conductivity of the autolizate and autolysis loss of mycelium dry weight.
