Predictive modelling of growth and enzyme production and activity by a cocktail of Pseudomonas spp., Shewanella putrefaciens and Acinetobacter sp.

The possibility was examined of developing a predictive model that combined microbial growth (increase in cellular number) with extracellular lipolytic and proteolytic enzyme activity of a cocktail of four strains of Pseudomonas spp. and one strain each of Acinetobacter sp. and Shewanella putrefaciens. Environmental conditions within the following matrix of conditions were examined: temperature 2-20 degreesC, pH value 4.0-7.5 and water activity (a(w)) 0.95-0.995 and a model was constructed, which predicted growth based on increase in cell number. Data on lipase production and protease activity were generated and will be available as a database, but no function could be identified, which was a good fit to these data, since most enzymatic production and activity occurred, as expected, during transition from exponential to stationary phase. Even at lower cell numbers, in more unfavourable conditions, hydrolysing effects were detectable, which made it difficult to construct a model combining both microbiological and enzymatic data. (C) 2003 Elsevier Science B.V. All rights reserved.