Production of concentrated bacteriocin solutions in high cell density bioreactors

Bacteriocins are natural proteinaceous antimicrobial substances produced by microorganisms like lactic acid bacteria to dominate the other microflora. Their use in the food industry as natural preservatives is tightly linked to the emergence of efficient and inexpensive production and purification procedures. The production of an anti-listeria bacteriocin, named Divercin, by Carnobacterium divergens, has been studied in batch, continuous culture and with viable cells immobilized in alginate gel beads retained in a plug flow bioreactor. The latter system gave the highest volumetric productivity with more than 10(5) AU L-1 h(-1), which was one hundred times the productivity of the batch system. A new simple (two steps) bacteriocin purification method was developed based on Triton -114 phase partitioning. The pilot production of bacteriocin can then be achieved allowing the exploration of the impact of such additions on the microflora of foodstuffs. (C) Inra/Elsevier, Paris.