RESUMEN
BACKGROUND: Fungal contamination of poultry feed causes economic losses to industry and represents a potential risk to animal health. The aim of the present study was to analyze the effectiveness of whey fermented with kefir grains as additive to reduce fungal incidence, thus improving feed safety. RESULTS: Whey fermented for 24 h at 20 °C with kefir grains (100 g L(-1) ) reduced conidial germination of Aspergillus flavus, Aspergillus parasiticus, Aspergillus terreus, Aspergillus fumigatus, Penicillium crustosum, Trichoderma longibrachiatum and Rhizopus sp. Poultry feed supplemented with fermented whey (1 L kg(-1) ) was two to four times more resistant to fungal contamination than control feed depending on the fungal species. Additionally, it contained kefir microorganisms at levels of 1 × 10(8) colony-forming units (CFU) kg(-1) of lactic acid bacteria and 6 × 10(7) CFU kg(-1) of yeasts even after 30 days of storage. CONCLUSION: Fermented whey added to poultry feed acted as a biopreservative, improving its resistance to fungal contamination and increasing its shelf life.
Asunto(s)
Alimentación Animal/microbiología , Fermentación , Microbiología de Alimentos/métodos , Hongos , Proteínas de la Leche/metabolismo , Aves de Corral , Animales , Aspergillus/efectos de los fármacos , Aspergillus/crecimiento & desarrollo , Recuento de Colonia Microbiana , Productos Lácteos Cultivados/microbiología , Aditivos Alimentarios , Contaminación de Alimentos/prevención & control , Conservación de Alimentos/métodos , Leche/microbiología , Penicillium/efectos de los fármacos , Penicillium/crecimiento & desarrollo , Rhizopus/efectos de los fármacos , Rhizopus/crecimiento & desarrollo , Trichoderma/efectos de los fármacos , Trichoderma/crecimiento & desarrollo , Proteína de Suero de LecheRESUMEN
Kefir-a traditional beverage whose consumption has been associated with health benefits-is a logical natural product to investigate for new probiotic strains. The aim of the present work was to isolate and identify kefir yeasts and select those with acid and bile tolerance to study their adhesion to epithelial cells and their transit through mouse gut. From 4 milky and 3 sugary kefir grains, 34 yeast strains were isolated and identified by means of classical microbiological and molecular-genetic methods (whole-cell protein pattern, internal-transcribed-spacer amplification, and analysis of restriction-fragment-length polymorphisms). We identified 4 species belonging to 3 genera-Saccharomyces cerevisiae (15 strains), Saccharomyces unisporus (6 strains), Issatchenkia occidentalis (4 strains), and Kluyveromyces marxianus (9 strains)-and selected 13 strains on the basis of resistance to low pH and bile salts. Among the strains selected, Kluyveromyces marxianus CIDCA 8154 and Saccharomyces cerevisiae CIDCA 8112 were further studied. Both strains evidenced the capacity to adhere to epithelial intestine-derived cells in vitro and to survive passage through the gastrointestinal tract of BALB/c mice. The investigation of the potential probiotic features of these kefir-yeast strains should be useful for the development of novel functional foods.