CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
CULTURE MEDIA DESIGN FOR SCREENING OF BIOGENIC AMINE PRODUCING LACTIC ACID BACTERIA
SAVINO M.J.; ARENA M. E.; MANCA DE NADRA M. C
Lugar: Mendoza-Argentina; Año: 2007 vol. 31 p. 301 - 301
Biogenic amines (BA), organic bases, generated by microorganisms could spoilage fermented foods. BA are measured by complex and expensive techniques, for this reason is important to set a reliable method for detection of lactic acid bacteria (LAB) that produce BA. The objective was to design a culture media that allows a qualitative detection of LAB isolated from apples that produce tyramine (tyra) from tyrosine (tyr). Two culture media were assayed: Media 1 (M1) in g/l: peptone, 5; yeast, 3; glucose (glc) 0.5; tomato juice, 2%v/v; bromocresol green, 0.04%; Media 2 (M2): peptone and yeast were not modified; glc, 1 g/l; tomato juice 5%v/v, bromocresol purple, 0.04%. The cultures media were added with tyr 1g/l, pyridoxal phosphate, 0.006 g/l; two initial pH values were tested: 4.5 and 5.2. Tyra was quantified by HPLC. In the first 5 days incubation pH indicators showed an acidification. The production of BA is indicated by media alkalization changing the colour media (M1). This fact was observed after 5 days incubation for strains 44, 66, 68 of L. plantarum and 37, 72 of L. brevis, at both pH. In M2 persisted yellow colour during the 10 days incubation. Tyr decarboxylase activity was corroborated for the strains 44 and 72 of L. plantarum. The initial pH did not modify the results. The design M1 appears to be a simple method to detect LAB that produce tyr.