|
Poster Presentation 6-19
Protease Production by a Streptomyces sp. Isolate from Brazilian Cerrado Soil: Culture Medium Optimization Employing Surface Response Statistical Design
L A. I. De Azeredo1, L. R. Castilho2, S.G.F. Leite3, R.R.R. Coelho1 and D. M. G. Freire4
1Instituto de Microbiologia Prof. Paulo de Góes / UFRJ, Brasil
2Programa de Engenharia Química - COPPE / UFRJ, Brasil
3Escola de Química / UFRJ, Brasil
2 21949-900, UFRJ, RJ, Brasil
Telephone: (55) 2121-25627360; Fax: (55) 2121-256272; E-mail: freire@pharma.ufrj.br
Several species from the Streptomyces genus are among the most important industrial microorganisms because of their capacity to produce numerous bioactive molecules, particularly antibiotics and enzymes. Actinomycetes are known to produce a variety of proteolytic enzymes, which are also used for a variety of industrial processes.
In this work, production of thermostable proteases by the strain Streptomyces sp. 594, isolated from Brazilian cerrado soil, was maximized by optimizing the culture medium using surface response methodology. Casitone and sugarcane molasses were employed as nitrogen and carbon sources (pH 7.0), and their concentrations were tested in the range from 0.1% to 0.5% (w/v) and from 0.1% to 3.0% (w/v), respectively, at 30°C.
A statistical analysis of the results allowed identification of the significant variables influencing protease activity. From experiments following a central composite design, the following mathematical model, based on normalized concentrations, was obtained:
Optimum casitone and molasses concentrations were 0.3% and 1.0% (w/v), respectively, giving a protease activity of 18900 U/L. The protease peaks were obtained at the end of the exponential and beginning of the stationary growth phase. Protease production appeared to be modulated by an inducer system, whereby the C:N ratio seemed to play a significant role.
|
