RESUMO
Simultaneous production of amyloglucosidase (AMG) and exo-polygalacturonase (exo-PG) was carried out by Aspergillus niger in substrate of defatted rice bran in a rotating drum bioreactor (RDB) and studied by a 31 × 22 factorial experimental design. Variables under study were A. niger strains (A. niger NRRL 3122 and A. niger t0005/007-2), types of inoculum (spore suspension and fermented bran), and types of inducer (starch, pectin, and a mix of both). Solid-state fermentation process (SSF) was conducted at 30 °C under 60-vvm aeration for 96 h in a pilot scale. Production of AMG and exo-PG was significantly affected by the fungal strain and the type of inoculum, but inducers did not trigger any significant effect, an evidence of the fact that these enzymes are constitutive. The maximum activity of exo-PG was 84 U gdm-1 whereas the maximum yield of AMG was 886.25 U gdm-1.
Assuntos
Aspergillus niger/enzimologia , Aspergillus niger/crescimento & desenvolvimento , Técnicas de Cultura Celular por Lotes/instrumentação , Reatores Biológicos/microbiologia , Glucana 1,4-alfa-Glucosidase/biossíntese , Poligalacturonase/biossíntese , Técnicas de Cultura Celular por Lotes/métodos , Ativação Enzimática , Desenho de Equipamento , Análise de Falha de Equipamento , Glucana 1,4-alfa-Glucosidase/química , Oryza/microbiologia , Poligalacturonase/químicaRESUMO
Glucoamylase production by Aspergillus niger in solid-state fermentation was optimized using factorial design and response surface techniques. The variables evaluated were pH and bed thickness in tray, having as response enzyme production and productivity. The bed thickness in tray was the most significant variable for both responses. The highest values for glucoamylase production occurred using pH 4.5 and bed thickness in the inferior limits at 2.0-4.2 cm. For productivity, the optimal conditions were at pH 4.5 as well and bed thickness from 4.4 to 7.5 cm. The optimal conditions for glucoamylase production while obtaining high activity without loss of productivity were pH 4.5 and bed thickness in tray from 4.0 to 4.5 cm, which resulted in an enzyme production of 695 U/g and productivity of 5791 U/h.
Assuntos
Aspergillus niger/metabolismo , Fermentação , Glucana 1,4-alfa-Glucosidase/biossíntese , Análise de Variância , Aspergillus niger/enzimologia , Fibras na Dieta/metabolismo , Concentração de Íons de Hidrogênio , Oryza/metabolismo , Componentes Aéreos da Planta/metabolismo , Análise de RegressãoRESUMO
It was the objective of the present study to increase the production of glucoamylase by Aspergillus awamori through solid state fermentation, using wheat bran as the main carbon source and (NH4)2SO4, urea, KH2PO4, glucose, maltose and starch as additional nitrogen, phosphorus, and carbon sources. The production of glucoamylase is strongly influenced by N and C sources. A 100% increase was observed when the (NH4)2SO4 was replaced by urea, with C/N = 4.8, using maltose as the additional carbon source. C/P ratios in a range of 5.1 to 28.7 did not induce glucoamylase production under the studied conditions.
Assuntos
Aspergillus/enzimologia , Glucana 1,4-alfa-Glucosidase/biossíntese , Aspergillus/crescimento & desenvolvimento , Carbono/metabolismo , Meios de Cultura , Fermentação , Glucose/metabolismo , Cinética , Nitrogênio/metabolismo , Oxirredução , Fósforo/metabolismoRESUMO
A strain of Aspergillus tamarii, a filamentous fungus isolated from soil, was able to produce both Ó-amylase and glucoamylase activities in mineral media supplemented with 1(per cent) (w/v) starch or maltose as the carbon source. Static cultivation led to significantly higher yields than those obtained using shaking culture. The production of amylases was tolerant to a wide range of initial culture pH values (from 4 to 10) and temperature (from 25 to 42degree C). Two amylases, once Ó-amylase and one glucoamylase, were separated by ion exchange chromatography. Both partially purified enzymes had optimal activities at pH values between 4.5 and 6.0 and were stable under acid conditions (pH 4.0-7.0). The enzymes exhibited optimal activities at temperatures between 50(degree) and 60(degree) C and wete stable for more than ten hours at 55(degree) C.
Assuntos
Aspergillus/metabolismo , Glucana 1,4-alfa-Glucosidase/biossíntese , alfa-Amilases/biossíntese , Aspergillus/enzimologia , Glucana 1,4-alfa-Glucosidase/química , alfa-Amilases/químicaRESUMO
A strain of Aspergillus fumigatus isolated from soil was able to produce biomass and high amylase activities in media containing alpha-methyl-D-glucoside (alphaMG), a synthetic analogue of maltose, as the only carbon source. alphaMG was a more effective inducer than starch and maltose at the same concentration: alphaMG cultures produced about 3 times more alpha-amylase and glucoamylase activity than starch cultures. Maximum production of alpha-amylase (60 U/mg) and glucoamylase (130 U/mg) was obtained in 8-10 days alphaMG cultures.
Assuntos
Amilases/biossíntese , Aspergillus fumigatus/enzimologia , Metilglucosídeos/metabolismo , Aspergillus fumigatus/crescimento & desenvolvimento , Meios de Cultura , Indução Enzimática , Glucana 1,4-alfa-Glucosidase/biossíntese , CinéticaRESUMO
Amylase production by a strain of Aureobasidium pullulans isolated in the laboratory was evaluated in liquid media (complex and synthetic) and in solid medium (wheat bran). There was an inhibitory effect in amylase production or amylase secretion by glucose. Asparagine was the best nitrogen source for amylase production (4-6 g/l). Only chlamidospores and melanin but not, amylase activity, were obtained with ammonium sulfate. Amylase production in solid culture was higher than the production obtained in the liquid media assayed. Optimum initial moisture content in solid culture ranged between 57 and 74%. No difference was observed in amylase production between solid media inoculated with cells grown in liquid or solid media.
Assuntos
Proteínas Fúngicas/biossíntese , Glucana 1,4-alfa-Glucosidase/biossíntese , Fungos Mitospóricos/enzimologia , alfa-Amilases/biossíntese , Meios de Cultura/farmacologia , Indução Enzimática , Fungos Mitospóricos/efeitos dos fármacos , Fungos Mitospóricos/crescimento & desenvolvimentoRESUMO
A produçäo de amiloglicosidase por Aspergillus awamori NRRL3112 em processo descontínuo alimentado é 92 por cento superior em relaçäo ao processo descontínuo em cultivos com 20g/l de concentraçäo total de fonte de carbono oriunda de farinha de mandioca. Uma análise da velocidade específica de produçäo mostra ser este resultado decorrente da reduçäo do efeito repressivo causado pela glicose, já que o efeito indutivo, relacionado à concentraçäo de polissacarídeo, também foi reduzido