ProduÃÃo de protease por Bacillus firmus via batelada alimentada utilizando-se perfis constante e exponencial de alimentaÃÃo

AUTOR(ES)

Claudemir Santos da Costa

DATA DE PUBLICAÇÃO

2005

RESUMO

The genus Bacillus is used extensively for production of industrial enzymes. B. firmus produces an alkaline protease compatible to be used as an additive in detergents. As in other Bacilli, protease in this microorganism is synthesized in response to the depletion of nutrients. The aims of this work were to test the instrumentation and control software, developed in the Laboratory of Biotechnological Processes, and to investigate the production of alkaline protease by B. firmus in cultivations with constant and exponential feed profiles. The cultivations were performed in a 4-liter working-volume bioreactor, using glucose and urea as carbon/energy and nitrogen sources, respectively. A microcomputer-controlled, predefined, open-loop regulation was used to implement the feed rate set point. The microcomputer was connected to a peristaltic pump through an 8-bit digital/analogic interface, and the programming language was Visual Basic 5. After an initial growth phase in batch mode, highly concentrated glucose solution was used to feed the bioreactor, so that volume variation could be neglected. During the fed-batch phase with constant feed profile, the specific growth rate, μ, varied in the range of 0.25-0.01 h-1. The specific production rate showed a maximum value at μ around 0.1 and 0.15 h-1, and the production was halted at μ equal to 0.05 h-1. Using the kinetic data obtained during constant fed-batch, an exponential feed profile was estimated to maximize enzyme production. Exponentially-fed-batch cultivation was then carried out with the estimated profile. Even though growth followed an exponential profile as predicted by the model, the production of protease was not enhanced. A third strategy of cultivation was carried out by the implementation of constant feed profiles stepwise, to guarantee the maintenance of μ in a supposedly ideal range for protease production (0.2 to 0.1 h-1), but, again, improvement was not observed. The production was higher in cultivations with constant profile than in cultivations under exponential profile or with different constant profiles

ASSUNTO(S)

perfis constante e exponencial produÃÃo de enzimas protease por bacillus firmus produtos bioativos processo via batelada alimentada quimica dos produtos naturais

Documentos Relacionados

• Efeitos da somatotropina bovina recombinante (BST), da raÃa e da alimentaÃÃo sobre a produÃÃo e a qualidade do leite de cabra na regiÃo Nordeste do Brasil
• Produção de hidrolisado proteico de pirarucu utilizando-se protease de Aspergillus flavo-furcatis e pancreatina
• Duas novas determinações da constante de decaimento por fissão espontanea do 238U, lambdaf, utilizando-se tecnicas de traços de fissão
• EstratÃgia de intervenÃÃo em educaÃÃo em alimentaÃÃo e nutriÃÃo
• Reduções enantiosseletivas de cetonas utilizando-se fermento de pão