Genetic diversity among Lactococcus sp. and Leuconostoc sp. strains using PCR-RFLP of insertion sequences ISS1-type, IS904, and IS982

PCR-RFLP analysis of commonly occurring insertion sequences ISS1-type, IS904 and IS982 in Lactococcus sp. and Leuconostoc sp. was used for the genetic differentiation of 17 strains of lactic acid bacteria. ISS1-type and IS982 were found in all analysed strains while 1S904 was present exclusively in strains belonging to Lactococcus sp. Amplification of ISS1-type IS sequences resulted in formation of about 820 bp long amplicons, except of strains Lactococcus lactis ssp. lactis E and Leuconostoc lactis R where extra DNA bands about 370 bp long were observed. Similarly for strains of Leuconostoc lactis M and N, additional DNA bands about 280 bp long were present. TaqI digestion of ISS1-type amplicons revealed that all analysed sequences belonged to the restriction type (ii) or (iii) for which major restriction products were 543 and 147 bp long. Amplification of IS904 from all strains of Lactococcus sp. generated amplicons about 1260 bp long. In three strains of Leuconostoc sp. M, N and R, shorter amplicons about 880 bp were observed whereas strains O and P did not contained IS904. Amplification of IS982 resulted in formation of amplicons about 1000 bp long and no extra bands were observed for all tested strains. TaqI digestion of amplification products showed that for strains C, I and F, G, H, belonging to Lactococcus sp. smaller DNA bands were visible suggesting that they contain two different types of IS9S2.