MODELING THE GROWTH AND BACTERIOCIN PRODUCTION BY LACTOBACILLUS-AMYLOVORUS DCE-471 IN BATCH CULTIVATION

A model was set up to describe the production of amylovorin L471 by La ctobacillus amylovorus DCE 471, on a laboratory scale, in which the ce lls are grown in MRS (deMau-Rogosa-Sharpe) broth. The main features of the dynamic model are: (i) increase of the biomass according to a log istic equation; (ii) non-growth-associated consumption of substrate (m aintenance metabolism); and (iii) primary metabolite kinetics for the bacteriocin production. The main purpose was to set up a simple empiri cal model to examine growth and bacteriocin production in different co nditions. Parameters estimated from a fermentation with 20 g l(-1) glu cose (w/v) could be used to predict the evolution of cell dry mass, gl ucose and lactic acid concentration of fermentations, performed with 5 , 30, 40 and 60 g l(-1) initial glucose. The influence of the operatin g temperature (30, 37 and 45 degrees C) on the model parameters was al so investigated. The proposed model was able to describe growth and ba cteriocin production in all cases. The specific bacteriocin production rate was found to vary strongly with temperature, with 30 degrees C a s the best value. Variation of the operating temperature from 37 to 30 degrees C appeared to significantly enhance the specific bacteriocin production.