Faculty of Food Technology and Biotechnology, University of Zagreb
Abstract
Lactic acid bacteria (Lactococcus lactis NZ9000, Lactococcus lactis MG1363, Lactobacillus plantarum I-UL4 and Lactobacillus johnsonii DSM 20553) have been screened for their ability to produce folate intracellularly and/or extracellularly. L. plantarum I-UL4 was shown to be superior producer of folate compared to other strains. Statistically based experimental designs were used to optimize the medium formulation for the growth of L. plantarum I-UL4 and folate biosynthesis. The optimal values of important factors were determined by response surface methodology (RSM). The effects of carbon sources, nitrogen sources and para-aminobenzoic acid (PABA) concentrations on folate biosynthesis were determined prior to RSM study. The biosynthesis of folate by L. plantarum I-UL4 increased from 36.36 to 60.39 µg/L using the optimized medium formulation compared to the selective Man de Rogosa Sharpe (MRS) medium. Conditions for the optimal growth of L. plantarum I-UL4 and folate biosynthesis as suggested by RSM were as follows: lactose 20 g/L, meat extract 16.57 g/L and PABA 10 µM.Ispitana je sposobnost mliječno-kiselih bakterija (Lactococcus lactis NZ9000, Lactococcus lactis MG1363, Lactobacillus plantarum I-UL4 i Lactobacillus johnsonii DSM 20553) da intracelularno i/ili ekstracelularno proizvedu folate. Najbolji soj za proizvodnju folata bio je L. plantarum I-UL4. Statistički je dizajn eksperimenta primijenjen radi optimiranja sastava podloge za uzgoj L. plantarum I-UL4 i biosintezu folata. Utvrđen je utjecaj koncentracija izvora ugljika i dušika, te para-aminobenzojeve kiseline na biosintezu folata, a zatim su metodom odzivnih površina određene optimalne vrijednosti glavnih parametara sinteze. U usporedbi s uzgojem L. plantarum I-UL4 u selektivnoj de Man-Rogosa-Sharpe podlozi, u optimiranoj se podlozi biosinteza folata povećala sa 36,36 na 60,39 μg/L. Optimalni je sastav podloge bio: 20 g/L laktoze, 16,57 g/L mesnog ekstrakta i 10 μM paraaminobenzojeve kiseline
