Resumo

Introduction and Objectives: Bacteriocins are defined as ribosomal synthesized proteins or protein complexes usually antagonistic to genetically closely related organisms. In addition, there is few published information related to technologic bioproduction of bacteriocin by Bifidobacterium animalis subsp. lactis. Bacteriocins are generally defined as peptides produced by bacteria that exhibit a spectrum of activity against a variety of microorganisms including Gram-positive and Gram-negative bacteria. The use of milk whey, as a culture medium, extols the concept of the production of a high-value biomolecule coupled with the environmental aspect, since the whey is a pollutant of dairy industries. So, in this context, the aim of this present work is to optimize the biotechnological production of bacteriocin by B. lactis in milk whey. Material and Methods: The fermentation conditions for the growth of Bifidobacterium lactis, in a rotating shaker, were 50rpm/37ºC/30h. Milk whey was prepared either in the presence or absence (control) of 1 % (w/v) L-cysteine, 1% (w/v) east extract, 1% (w/v) inulin or 1% (w/v) tween 80. Cell growth, pH, glycolysis concentration and bacteriocin activity were determined every 3 hours for 30 hours. The bacteriocin produced was tested against several strains of Listeria monocytogenes, Lactobacillus sakei (ATCC 15521) and Escherichia coli (ATCC 25922). Results and Conclusions: Compared to control, the addition of east extract in milk whey increased by 9 % the counts of B. lactis (9.8 Log CFU/mL). Moreover, the bacteriocin was produced at the end of exponential phase (20 h) and its activity was 200 AU/mL in the pH 4.2. In the absence of supplementation (control) in the milk whey, bacteriocin activity was 60 AU/mL. On the other hand, this bacteriocin has activity only against one strain of L. monocytogenes (ATCC 13932). In conclusion, the addition of east extract in the milk whey favored the cell growth and bacteriocin activity. The whey, because it is a culture medium cheaper than synthetic media MRS and BSM, can decrease the cost of production of biomolecule with high added value and its use is therefore advantageous.