Growth parameters and bacteriocin expression analysis of E.mundtii CRL35in a meat model system

BONACINA J; SUAREZ, N; SESMA F; RAYA RAUL; FADDA S; SAAVEDRA L

Congreso; SAIB2014; 2014

Enterococcus (E) mundtii CRL35 is a bacteriocinogenic non starter strain with biotechnological potential in biopreservation and food safety. Food model systems constitute a useful and necessary instance to study the behavior of an organism before its application in a real matrix. The aim of this work was to study the growth, acidifying capacity, antimicrobial activity and the expression of bacteriocin genes in a food model based on meat extract at 25°C, in comparison with the laboratory culture media LAPTg. In this sense, i) cell growth (OD600); ii) pH and iii) antimicrobial activity against the food-borne pathogen Listeria monocytogenes, and the expression of structural (munA) and ABC transporter (munB) genes of Enterocin CRL35 by qRT-PCR, were determined. E. mundtii CRL35 was able to grow in the food model system reaching an OD600 of 3.12 with a final pH of 4.6 after 25 h incubation. The same growth and acidification capability were observed in LAPTg (pH=4.06 and DO600 =3.04). Regarding the antimicrobial activity, an optimal enterocin CRL35 production was recorded after 10 h, being highly superior in LAPTg (3.6 x 103 UA/ml). Furthemore, expression analysis by qRT-PCR evidenced that munA and munB are expressed in both media and at the same level. These results suggest that E. mundtii CRL35 can be employed as a bioprotective nonstarter culture.