Identification of lactic acid bacteria isolated from probiotic products

Jedanaest bakterijskih sojeva, izoliranih iz komercijalno dostupnih probiotičkih pripravaka na hrvatskom tržištu je odabrano za reidentifikaciju. Klasičnim mikrobiološkim metodama su sojevi okarakterizirani kao gram-pozitivni, nesporogeni i katalaza-negativni. RAPD metoda je provedena s početnicama za bakterije mliječne kiseline kako bi potvrdila raznolikost izoliranih sojeva. Identifikacija na razini roda je provedena PCR reakcijama s početnicama za rodove Lactobacillus i Bifidobacterium. Sojevi 1, 2a, 4, 5, 6, 8/1, 8/2 i 9 su pokazali pozitivan signal za rod Lactobacillus, a sojevi 3 i 8/2 pozitivan signal za rod Bifidobacetirum. Fenotipska identifikacija je provedenim API 50 CHL testom. Sojevi 1 i 2a su identificirani kao Lactobacillus rhamnosus, a sojevi 4, 5, 6 i 9 kao Lactobacillus fermentum što odgovara deklaracijama proizvoda. Za soj 8/2, koji je genetičkim metodama povrđen kao mješoviti soj, API sustav je potvrdio neprihvatljiv profil. Tijekom uzgoja izoliranih bakterijskih sojeva u tekućim podlogama praćeni su parametri proizvodnje mliječne kiseline i promjene pH vrijednosti.Eleven strains were isolated from commercially available probiotic preparations on the Croatian market and selected for reidentification. The classical microbiological methods characterized strains as Gram-positive, nonsporogenic and catalase-negative. RAPD method with primers for lactic acid bacteria was used in order to confirm diversity amonf isolated strains. Identification at the genus level was confirmed by PCR reactions with primers for the Lactobacillus and Bifidobacterium genera. Strains 1, 2a, 4, 5, 6, 8/1, 8/2 and 9 showed the positive signal for the Lactobacillus genus and strains 3 and 8/2 showed positive signals for the Bifidobacetirum genus. Phenotypic identification was performed with API 50 CHL test. Strains 1 and 2a were identified as Lactobacillus rhamnosus, and strains 4, 5, 6 and 9 as Lactobacillus fermentum which corresponds to the products label. Strain 8/2 was defined as mix culture with genetic methods and API system confirmed his unacceptable profile. Parameters and production of lactic acid and the pH value were also monitored during the cultivation of isolated bacterial strains in liquid media