Novel description of Enterococcus faecium citrate gene cluster

QUINTANA, I; MARTINO, G; ESPARIZ, M; BLANCATO, VS; MAGNI, C

Rosario, Santa Fe

Congreso; L Reunión Anual de SAIB; 2014

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Enterorococcus faecium is one of the most controversial microorganisms used in food industry due to its role as causal agent of bacteremia and other human infections. Nevertheless it is used as probiotic, and its presence in cheese microbiota as non-starter lactic acid bacteria is truly beneficial for the flavor developing process as a consequence of citrate metabolism. Although citrate metabolism was studied in E. faecium no data about genes involved in this pathway has been reported. We have previously stated a classification of E. faecium according to cit genes present in its genome (cit- and cit+ type I and II). Sequencing of E. faecium GM75 (type I) cit cluster allowed us to identify the insertion sequence IS256 in regulatory regions, which is not present in E. faecium IQ23 (type I). We have analyzed gene function through transport and metabolism and 14C-citrate transport experiments demonstrating that citrate intake and degradation is functional in both strains, with no significant differences. Aroma compound diacetyl was detected, proving the contribution to flavor development of these bacteria, although similar production amounts were obtained for both strains also. In this work we reach a first approach to the description of genetic organization and biochemistry of E. faecium cit cluster and give evidence to the great diversity it is subject to.