CONICET | Buscador de Institutos y Recursos Humanos

Trabajo enviado a publicación 29 de Diciembre de 2012(en revisión). A screening of strains belonging to Propionibacterium genus was performed in hens 19 from conventional production systems and backyard hens. Propionibacteria were 20 isolated from the large intestine and identified by physiological and biochemical tests. 21 Genus identification was confirmed by PCR reaction with genus-specific primers. PCR 22 amplification of the 16S rRNA genes was performed; products were sequenced and 23 compared to known 16S rDNA sequences from databases. As a result, the presence of 24 the genus Propionibacterium was demonstrated in 16 % of hens from conventional 25 production systems and 50 % of backyard hens. The 16S rDNA sequences of 5 isolated 26 strains showed 99 % identity with P. acidipropionici, while the sequences of other 4 27 strains had 98 % identity with P. avidum DSM 4901 and P. propionicum DSM 43307. 28 A phylogenetic tree was constructed and P. acidipropionici from poultry were clustered 29 with known sequences of this species from different origins. The remaining 4 strains 30 were included in a new cluster and identified as P. avidum based on their biochemical 31 behaviour. The strains were resistant to low pH, bile salts and to in vitro sequential 32 gastrointestinal digestion. Growth and short chain fatty acids in a natural model of cecal 33 water demonstrate that the ability to metabolize residual carbohydrates and to develop 34 in the intestinal environment is strain-dependent as well as the adhesion to the intestinal 35 tissue, which are desirable properties for probiotic strains selection. Results contribute 36 to the knowledge of autochthonous species of the gastrointestinal tract of poultry and 37 their potential for probiotics development.