CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
IMPROVEMENT OF A CHEMICALLY DEFINED MEDIUM FOR THE SUSTAINED GROWTH OF Lactobacillus plantarum. NUTRITIONAL REQUIREMENTS.
SAGUIR F.M.; MANCA DE NADRA M.C.
Año: 2007 vol. 54 p. 414 - 414
The aims of this work were to improve a basal synthetic medium (BM) for the growth of Lactobacillus plantarum strains and to establish their amino acid requirements. In the most nutritionally demanding bacterium the amino acids utilization was analyzed. First, the improved BM (LPSM medium) was defined by increasing some vitamins, especially p-aminobenzoic acid, vitamin B12 and biotin, 5-fold phenylalanine, histidine, isoleucine, leucine, lysine, methionine, proline, serine, threonine and tryptophan, 10, 60 and 75-fold valine, arginine and tyrosine, respectively in the BM. In this condition the N8 and N4 strains of Lact. plantarum grew rapidly reaching final cell densities as those obtained in MRS medium. When cysteine, leucine, valine, isoleucine, threonine, and glutamic acid were individually removed from this medium, bacterial growth was significantly reduced or annulled indicating that they were essential amino acids for growth. The N4 strain also required lysine and tryptophan in addition to the six amino acids necessary for growth. Lact. plantarum N4 mainly consumed essential amino acids such as valine, lysine, cysteine and threonine and the stimulatory amino acid arginine. Thus, the BM was improved mainly on the basis of annulling limitations with respect to amino acids. With this improved medium cell densities in order of 109 cfu/mL have been achieved indicating that the LPSM medium could be used for conducting metabolic and genetic studies on Lact. plantarum. The low amino acid levels in orange juice suggest that they not may satisfy the totality of nitrogen requirement for the development of Lact. plantarum in the natural environmental.