CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
LACTIC ACID BACTERIA ON FREEZE-DRIED FORM FOR THEIR APPLICATION IN RANICULTURE
Autor/es:
MONTEL MENDOZA, G.; PASTERIS, S.E.; OTERO, M.C.; BUHLER, M.I.; NADER-MACÍAS, M. E.
Lugar:
Tucuman
Reunión:
Congreso; VII Congreso Argentino de Microbiologia General SAMIGE del Bicentenario; 2011
Institución organizadora:
Sociedad Argentina de Microbiologia General
Resumen:
LACTIC ACID BACTERIA ON FREEZE-DRIED FORM FOR THEIR APPLICATION IN RANICULTURE Gabriela Montel Mendoza1, Sergio E. Pasteris1, María C. Otero2, Marta I. Búhler1, María E. Nader-Macías2 1 INSIBIO, CONICET, UNT 2 CERELA, CONICET (fnader@cerela.org.ar) Lactic acid bacteria (LAB) are used as probiotics in aquaculture, being raniculture an emerging area where there are no available probiotic products containing indigenous strains. In previous work, LAB strains from Lithobates catesbeianus hatcheries were isolated and selected by their beneficial characteristics to prevent red-leg syndrome (RLS). The protective effect of probiotics depends on the administered concentration and the preservation method. The freeze-drying process has commonly been used to maintain the viability and functional properties of bacteria. In this work, the effect of different concentrations of cryoprotective supports [skim milk, whey protein concentrate (WPC), sucrose, lactose] individually added or combined was evaluated on the survival of beneficial LAB strains: L. lactis CRL 1584 and 1827; L. garvieae CRL 1828 and Lb. plantarum CRL 1606, during freeze-drying. Beneficial LAB properties included production of inhibitory metabolites (lactic acid, hydrogen peroxide or bacteriocin), and/or hydrophobicity or autoaggregation characteristics. The strains were grown in MRS broth for 24 h at 37¡ãC, washed twice, resuspended in the cryoprotective media and in water, and the number of CFU was determined (pre-lyophilized). Then, the samples were frozen at -70¡ãC and desiccated under vacuum for 12 h at 0.3 mbar (post-lyophilized). A full two-factor ANOVA test, considering dryingmedia and strain, of the decrease in viability during the freeze-drying process was applied. Results showed that the number of viable cell was significantly higher for all the LAB strains (p ¡Ü 0.005) when dried in the presence of all the cryoprotective media compared with water as control, being L. lactis CRL 1584 the most sensitive strain to the drying-process. The significance of the interactions between all the studied factors supports that there is not an unique optimal drying condition for all the strains evaluated. Thus, the best conditions for each LAB strain were selected considering the cost of the cryoprotective media, mainly WPC and sucrose, which represent the main products of milk and sugar cane industries in Argentina. The cryoprotectors chosen were 10% WPC for L. lactis CRL 1584, 10% sucrose for L. lactis CRL 1827 and Lb. plantarum CRL 1606, whilst a mixture of 5% WPC and 5% sacarose was required for L. garvieae CRL 1828. Also, the freeze-drying process did not affect the expression of the beneficial properties (production of inhibitory metabolites, hydrophobicity and autoaggregation) of the LAB strains under study. These studies represent the first approach on the resistance to the freeze-drying process of LAB to be used in raniculture and the maintenance of their beneficial properties. Further assays are being performed to evaluate the viability of LAB and their beneficial properties during storage.