Insertion sequence analysis of protoplast fused strains of Lactococcus lactis ssp. cremoris

The use of insertion sequence probes for the analysis of fusants obtained following protoplast fusion is described. Hybridization of both total and plasmid DNA from parent and fusant strains with probes to IS904 and ISS1 showed that of the four protoplast fusions examined, three appeared to involve a rearrangement of genetic material while in the fourth the fusant appeared similar to one of the parental strains. This method of analysis provides more information about the changes induced by protoplast fusion than that obtained by monitoring the acquisition or loss of individual characteristics.