Strain improvement of predacious fungi: Screening for the ability of mutant strains of Duddingtonia flagrans to withstand ruminant gut passage

Mutant strains of the fungus Duddingtonia flagrans were generated by chemical mutant ethyl methane sulphonate and albendazole by random mutagenesis. These mutant strains (DF-ABZ and DF-EMS) were characterized for their chlamydospore forming ability, their germination potential and survivability following ruminant gut passage compared to those of the wild strain of D. flagrans. The results of the study indicated that wild strain (DF-CON) of D. flagrans could produce significantly increased numbers of chlamydospores in barley grain culture compared to that of the mutant strains. The germination potential of chlamydospores of ABZ mutant strain (DF-ABZ) of D. flagrans was more compared to that of wild strain (DF-CON) and EMS mutant (DF-EMS) strain of D. flagrans. Both the wild strain (DF-CON) and ABZ mutant (DF-ABZ) strain of D. flagrans had the ability to withstand anaerobic and enzymatic environment of ruminant gut and were excreted in the faeces of goats. However, EMS mutant (DF-EMS) strain of D. flagrans could not withstand ruminant gut passage and thus could not be re-isolated from the faeces of goats.