INTERMICROBIAL «SELF-NON-SELF» DISCRIMINATION IN «DOMINANT-ASSO-CIANT» PAIR OF PROBIOTIC STRAINS OF ESCHERICHIA COLI M-17 AND E.COLI LEGM-18

Abstract

Aim. To use earlier developed method of intermicrobial «self-non-self» discrimination in «dominant-associant» pair for the assessment of foreignness of probiotic cultures of Escherichia coli M-17 (with pathogenicity island) and E. coli LEGM-18 (without pathogenicity island). Materials and methods. As dominants reference and clinical strains of bifidobacteria were used in the work, cultures of E. coli M-17 and E. coli LEGM-18 were taken as associants, differing in the presence of genes which code colibactin. Detection of the phenomenon of microbial discrimination was conducted according to the developed algorithm (Bukharin O.V., Perunova N.B., 2011) based on the principle of metabolite induction as a result of preliminary coincubation of dominants (bifidobacteria) with supernatant of associants and the formation of feed back in «dominant-as-sociant» pair. Special growth properties, biofilm formation, and antilysozyme activity served as biological characteristics of investigated coliform bacteria. Results. Testing of E. coli M -17 culture revealed depression of biological properties under investigation and it was estimated as «non-self» possibly due to the presence of pathogenicity island whereas E. coli LEGM-18 (without this fragment) sharply strengthened its biological characteristics and was subjected to assessment as «self». Conclusion. Use of intermicrobial «self-non-self» discrimination in «dominant-associant» pair is promising as basic method when selecting probiotic strains and cultures for creation of new symbiotic compositions and is suitable for quality control of probiotic products.