Resumo

Bacteriocins produced by lactic acid bacteria have received great attention because of their use as natural food preservatives. Streptococcus bovis HC5 is a lactic acid bacterium that produce a promising commercially valuable bacteriocin (bovicin HC5). Considering that S. bovis HC5 is an aerotolerant anaerobe with very rapid growth rates and simple nutritional requirements, the fermentation processes for bovicin HC5 production could be performed by using low cost substrates. The objective of this study was to investigate the effect of the agroindustrial residues on bovicin HC5 production by S. bovis HC5. Batch cultures were grown in basal medium supplemented with sugar cane juice (final sugar concentration of 100 g/L) or cheese whey (final lactose concentration of 24 g/L) as carbon sources. The incubation were carried out at 39°C in sealed anaerobic serum bottles (50 ml) or in 500 mL fleaker beaker flasks that were continuously purged with O2-free carbon dioxide (CO2). Samples were taken at 0, 12, 24 and 48 hours and tested for bacteriocin activity in culture supernatants and in cell-free extracts obtained from cells treated with acidic NaCl solution (100 mM, pH 2.0). Streptococcus bovis HC5 cultures produced bovicin HC5 in cheese whey and sugar cane juice and maximal volumetric productivity was obtained after 12 h of incubation in sealed anaerobic bottles. At this time interval, the antimicrobial activity of bovicin HC5 detected in cell extracts was 2650 AU ml^-1 h^-1 for sugar cane juice and 2133 AU ml^-1 h^-1 for cheese whey. The amount of cell-associated bovicin HC5 was always greater than cell-free bacteriocin, regardless of the condition of incubation. These results suggest that S. bovis HC5 is a versatile lactic acid bacterium that can utilize alternative carbon sources for bovicin HC5 production. The use of agroindustrial residues as carbon sources could have an economical impact on bovicin HC5 production. Apoio: CNPq, CAPES