Abstract
The bacterium symbionts of the Morocco, SP2, Italian and Slovak Steinernema strains of long dauer phenotype were isolated and phenotypically characterized. Each proved Xenorhabdus according to cell and colony morphology, dye uptake, catalase negativity, as well as on the basis of their lecitinase, lipase and proteolytic activities. In gnotobiological tests the nematodes from which they had been isolated grew on it and produced fertile progeny in agar plates as well as in liquid culture in our laboratory fermentor. Each bacterium strains produced antibiotics of medium level and proved ampicillin resistant. The Morocco strain, however, expressed a low degree of ampicillin resistance. The sequence analysis and taxonomic identification will be accomplished soon.