This work aimed to characterize recombinant strains, with a high production level of L-asparaginase, previously obtained by protoplast fusion between Bacillus subtilis and Bacillus cereus. The genetic relationship between fusants and their parents was determined using a simple PCRrestriction fragment length polymorphism (RFLP) of 16S rDNAs -based method, and by analyzing the specifi c L-asparaginase genes and protein patterns. Our results indicate that all fusants have morphological characteristics and specifi c L-asparaginase genes similar to the Bacillus cereus strain whereas protein pattern and 16S rDNAs -RFLP analysis show mixed characteristics from both parents. Different genetic relationships were found between each fusant and its parental strain. These results confi rm that protoplast fusion is an important technique in strain improvement. It was used to combine genes from different organisms for creating strains with desired properties