Characterization of Bifidobacteria and Lactobacilli with Intestinal Origin with Molecular Typing Methods

ABSTRACT

We isolated 121 Bifidobacteria and 169 Lactobacillus strains from human faeces samples. The species belonging was proved by help of PCR with species-specific primers, SDS-PAGE of whole soluble cell proteins and ARDRA. The strain diversity was evaluated by PFGE. The most occurred Lactobacillus species were L. plantarum (15 different strains), L. gasseri (14 strains), L. casei (11), L. fermentum (11). Among Bifidobacteria B. longum (51 strains) and B. bifidum (26 strains) dominated over the rest species. An original finding was the isolation of four strains L. delbrueckii ssp. lactis and five strains L. helveticus. It is very rarely to find these species in human intestinal samples and the presence of L. lactis and L. helveticus could be connected with higher cheese consumption in Bulgaria. Lactobacillus and Bifidobacteria strains isolated from gastrointestinal ecosystem could be successfully identified at species level using the combination of the three methods. The ARDRA with the enzymes Hae III, Msp I and Eco RI gave satisfactory differentiation of Lactobacillus species. The methodology based on ARDRA is easier and faster than SDS-PAGE but SDS-PAGE proved higher abilities to differentiate the strains at species level. PFGE proved its high discriminatory power to differentiate the isolates at strain level.

Keywords:

• bifidobacteria
• lactobacilli
• PFGE