RESUMO
In a search for microorganisms producing extracellular protease with unhairing activity, Bacillus subtilis IIQDB32 was isolated. Protease formation was significantly stimulated by glucose, tryptone, yeast extract, Ca(2+) and Mn(2+), but was repressed by ammonia and Fe(2+).
RESUMO
The substitution of chemical depilatory agents in the leather industry by proteolytic enzymes produced by Bacillus species has an important economical and environmental impact. In previous assays, a Bacillus sp. showing a promising depilatory activity was isolated. In this paper, a culture medium that stimulated the synthesis and segregation of depilatory proteases, was selected. The influence of pH, oxygen supply rate (KLaC*), and inoculum age was evaluated on cell growth and protease production. Assays were carried out in lab bioreactors (1.2-1.4 l) at 37 degrees C. Five different media that differed in carbon and nitrogen sources were tested. pH ranged from 4.0 to 8.5. KLaC* varied between 40 and 470 mmol/lh. The best medium culture for protease production contained: nutrient broth (Britania) 8 g/l, yeast extract (Britania) 3 g/l, and mineral salts. Protease production was more effective at pH of 6.7, KLaC* of 360 mmol/lh, and inoculum age of 12 hours. These experimental conditions led to the following results: maximum proteolytic activity 2700 U/ml, overall volumetric protease productivity 300 u/ml-h, average specific growth rate 0.62 h-1, and average specific protease production rate 2.50 x 10(5) U/gh.
Assuntos
Bacillus/enzimologia , Proteínas de Bactérias/isolamento & purificação , Endopeptidases/isolamento & purificação , Remoção de Cabelo/métodos , Microbiologia Industrial , Bacillus/efeitos dos fármacos , Bacillus/crescimento & desenvolvimento , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Carbono/metabolismo , Meios de Cultura/farmacologia , Endopeptidases/biossíntese , Endopeptidases/genética , Indução Enzimática/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Nitrogênio/metabolismo , Oxigênio/metabolismoRESUMO
The substitution of chemical depilatory agents in the leather industry by proteolytic enzymes produced by Bacillus species has an important economical and environmental impact. In previous assays, a Bacillus sp. showing a promising depilatory activity was isolated. In this paper, a culture medium that stimulated the synthesis and segregation of depilatory proteases, was selected. The influence of pH, oxygen supply rate (KLaC*), and inoculum age was evaluated on cell growth and protease production. Assays were carried out in lab bioreactors (1.2-1.4 l) at 37 degrees C. Five different media that differed in carbon and nitrogen sources were tested. pH ranged from 4.0 to 8.5. KLaC* varied between 40 and 470 mmol/lh. The best medium culture for protease production contained: nutrient broth (Britania) 8 g/l, yeast extract (Britania) 3 g/l, and mineral salts. Protease production was more effective at pH of 6.7, KLaC* of 360 mmol/lh, and inoculum age of 12 hours. These experimental conditions led to the following results: maximum proteolytic activity 2700 U/ml, overall volumetric protease productivity 300 u/ml-h, average specific growth rate 0.62 h-1, and average specific protease production rate 2.50 x 10(5) U/gh.
RESUMO
The substitution of chemical depilatory agents in the leather industry by proteolytic enzymes produced by Bacillus species has an important economical and environmental impact. In previous assays, a Bacillus sp. showing a promising depilatory activity was isolated. In this paper, a culture medium that stimulated the synthesis and segregation of depilatory proteases, was selected. The influence of pH, oxygen supply rate (KLaC*), and inoculum age was evaluated on cell growth and protease production. Assays were carried out in lab bioreactors (1.2-1.4 l) at 37 degrees C. Five different media that differed in carbon and nitrogen sources were tested. pH ranged from 4.0 to 8.5. KLaC* varied between 40 and 470 mmol/lh. The best medium culture for protease production contained: nutrient broth (Britania) 8 g/l, yeast extract (Britania) 3 g/l, and mineral salts. Protease production was more effective at pH of 6.7, KLaC* of 360 mmol/lh, and inoculum age of 12 hours. These experimental conditions led to the following results: maximum proteolytic activity 2700 U/ml, overall volumetric protease productivity 300 u/ml-h, average specific growth rate 0.62 h-1, and average specific protease production rate 2.50 x 10(5) U/gh.