Lactic acid bacteria (lab) and toxicogenic fungi isolated from brewer’s grains used in feeding pig

GERBALDO G., ; PEREYRA C., ; CAVAGLIERI L., ; RUIZ F., ; PASCUAL L., ; DALCERO A., ; BARBERIS L.

San Miguel de Tucumán. Tucumán

Congreso; Simposio de Bacterias Lácticas; 2009

LACTIC ACID BACTERIA (LAB) AND TOXICOGENIC FUNGI ISOLATED FROM BREWER’S GRAINS USED IN FEEDING PIG. G.A. Gerbaldo, C. Pereyra, L. Cavaglieri, F. Ruíz, L. Pascual, A. Dalcero, L. Barberis Departamento de Microbiología e Inmunología. Universidad Nacional de Río Cuarto. Ruta 36 Km. 601. (5800) Río Cuarto. Córdoba. Argentina. ggerbaldo@exa.unrc.edu.ar    Argentina pig production is facing a new stage in its evolution, however, food costs represent between 70 and 80% of the total production cost, which is why many producers resort to the use of co-products of agro-industry as brewery waste. These alternative foods are cheap and readily available but it is susceptible to fungal colonization and mycotoxin. As consequence, the research was directed toward developing methods of natural prevention against of fungal contamination using BAL, who possess an antimicrobial activity through competition for nutrients as well the production of various antimicrobial compounds such as bacteriocins, organic acids and hydrogen peroxide. The objective was to study the lactic flora and the mycobiota, to isolate and identify species of Aspergillus and to define aflatoxicogenic profile of strains isolated from brewer’s grains to feeding pigs. The samples presented an average aW of 0992 and 0989 and average values of pH 5.67 ± 1.12 and 5.25 ± 0.99 at day 0 and 7 of storage, respectively. Fungal counts showed a range of 1 x 102 – 3.9 x 106 CFU/g and 6.9 x 103 – 6.6 x 106 CFU/g  in DRBC and 3 x 102 - 8 x 106 CFU/g and 1 x 103 – 6.6 x 106 CFU/g for DG18, at the day 0 and 7 of storage, respectively. All the samples showed high counts of yeasts. The toxicogenic genus highest incidence was Aspergillus spp. (76.92 and 73.91%) followed by Penicillium spp. (65.38 and 52.17%) and proportion lesser the genera Cladosporium spp. (30.76 and 26.08%) and Alternaria spp. (15.38 and 17.39%) at days 0 and 7 of storage, respectively. In Aspergillus genus, the most frequent strain in both samples was A. flavus (75.1 and 92.6% days 0 and 7) following by A. fumigatus (21.7 and 4.9% days 0 and 7) and aggregate A. niger (2 and 1.5% days 0 y 7). The counts of LAB showed a range of 1.9 x 105 – 2.7 x 109 CFU/g and 1.19 x 107 – 4.4 x 109 CFU/g at the day 0 and 7, respectively. The genus more frequently isolated was Leuconostoc spp., followed by Lactobacillus spp. and lesser Pediococcus spp. Toxicogenic profile of 138 strains of A. flavus showed that 86.2% produced AFB1. The average production of AFB1 was 4.93 ± 6.2 ppm. Fungal counts exceeded the maximum allowed 1 x 104 CFU/g for hygienic quality. The food is not considered sufficiently fit to be eaten by animals and presented strains potentially toxicogenic as A. flavus, A. fumigatus and belonging to the aggregate A. niger. Most strains of Aspergillus section Flavi were able to produce AFB1. The BAL was adapted to this ecological niche may studied as biocontrol of fungi toxicogenic, besides their probable probiotic properties in pigs that consumed this food.