Abstract

GORLACH-LIRA, Krystyna et al. Response surface analysis on the effect of temperature and pH on Growth and proteolytic activity of thermophilic Bacillus sp. Braz. arch. biol. technol. [online]. 2010, vol.53, n.5, pp. 1067-1072. ISSN 1516-8913.  http://dx.doi.org/10.1590/S1516-89132010000500009.

Proteolytic activity and cell biomass of thermophilic Bacillus sp. strain were evaluated at various levels of initial pH and temperature by applying response surface methodology. The mineral medium containing yeast extract (0.01%) and starch (1%) was used throughout the experiment. The results of statistical analysis revealed the polynomial model with high coefficient of determination (R² = 0.8) for the biomass and total proteolytic activity of the strain studied. This model showed a satisfactory adjustment of the statistic model with the experimental data. The p values showed that the temperature and pH had significant effect on biomass and proteolytic activity (P<0.05) of strain tested. The highest proteolytic activity (2.333 U/ml/h) of the Bacillus sp. was predicted at 41º C and pH 4.8. The high biomass values were observed at broad range of temperature and pH.

Keywords : Bacillus; proteolytic activity; response surface methodology.