Effect of carbon sources on Lactobacillus curvatus ACU-1 growth and bacteriocin production

ALVAREZ, ORNELLA E.; GARRO OSCAR A.; CAYRÉ, MARÍA E.; CASTRO MARCELA P.

San Miguel de Tucumán

Simposio; V International Symposium of Lactic Acid Bacteria. SIBAL 2016; 2016

CERELA

The strain Lactobacillus curvatus ACU-1, isolated from artisanal dry sausages manufactured in Chaco (Argentina), produces a bacteriocin which is active against several strains of Staphylococcus aureus and Listeria monocytogenes (Castro et al, 2011). This inhibitory substance showed to be heat stable, effective after refrigerated storage and freeze/thaw cycles and even active against pathogens when produced under refrigeration at 3% NaCl concentration. Thereby, bacteriocin application in biopreservation of meat products seems promising. Biopreservation can be applied to food by the incorporation of bacteriocinogenic strains as protective cultures or by the addition of the bacteriocin produced by conventional fermentation (Ananou et al., 2008). In both cases, it is necessary to determine the influence of factors involved in fermentative processes to optimize biomass or bacteriocin production.The aim of this study was to investigate the effect of different carbon sources on Lb. curvatus ACU-1 growth and bacteriocin production.Different carbon sources were evaluated: glucose, mannose, fructose, maltose, sucrose and lactose. Each independent variable was investigated at 20 g/l.Nutritive broth (MRS) was prepared by replacing original carbon source with the aforementioned ones, each at a time. The experiments were carried out in 250 ml flasks containing 200 ml of medium, which were incubated at 30°C for 36 h. Cell density was monitored spectrofotometrically (optical density at 600 nm, OD600nm). Cell dry mass (CDM) was determined by linear regression from plots of OD versus cell dry weight (g/l). Antimicrobial activity was checked by agar well diffusion method against Listeria innocua ATCC 33090. The bacteriocin yield or specific bacteriocin production YB/X (AU/g CDM) -which is the yield of bacteriocin per unit of cell mass- and the specific bacteriocin production rate qbac (AU/g CDM.h) were calculated. Data for maximal biomass and bacteriocin production were subjected to analysis of variance (ANOVA).The production of both biomass and bacteriocin by L. curvatus ACU-1 is stimulated by different carbon sources. These results together with the study of other sources of nutrients comprise the foundation for the optimization and substrate selection for the scale-up of biomass and bacteriocin production.