Molecular Identification and Partial Characterization of Pediococcus sp. and Leuconostoc sp. Isolated from Traditionally Made Dairy Products

Lactic acid bacteria (LAB) are group of commercially important organisms that play an important role in the fermentation process of hexose sugars into lactic acid and they are videly used in dairy industrial applications since they were designated as "generally recognised as safe" organisms. In order to isolate laktic acid bacteria (LAB), forty fermented food samples were collected and 160 bacterial strains were purified and identified from those samples. According to morphological characteristics, 62 isolates (38.75%) were classified as cocci and all these cocci were found to be as catalase negative and grown well on MRS agar plates. Coccobacilli and bacilli forms were observed in 66 (41.25%) and 19 (11.875%) isolates respectively. Total of 13 isolates (8.125%) were classified as "others" (according to morphological characteristics) and excluded from rest of experimental process. For molecular identification of Leuconostoc sp. and Pediococcus sp., 16S and 23S rDNAs (respectively) were amplified with the aid of PCR and 34 of them were classified as Pediococcus whilst 4 of them were designated as Leuconostoc. These newly isolated strains were tested for their antimicrobial activity and more than one strains exhibited antimicrobial activity against to S. paratyphi and E. faecali. All tested strains showed relatively lower (<= 10mm in diameter) antimicrobial effect against P. mirabilis, E. coli and C. jejuni while P. aeruginosa showed resistancy against all bacteriocins produced tested isolates. Result of this study revealed that majority of the tested (n=20) isolates were resistant to erythromycin, chloramphenicol and rifampin. All isolates were investigated for the presence of plasmid vectors and 10 of them found having at least 1 plasmid vector.