Isozyme Variation Among Bacterial Isolates Originating From the Screwworm Fly (Diptera: Calliphoridae) 1

Isozyme surveys were used to compare genetic variation within and among strains of the bacterium, Proteus rettgeri (Hadley, Elkins, and Caldwell). One strain was a standard American Type Cell Culture strain (ATCC 9250), whereas eight other strains were recovered from larva or pupa of the screwworm fly, Cochliomyia hominivorax (Coquerel), of varied geographic or animal host origins. Observations of 16 different enzyme systems of each bacterial isolate revealed extensive inter- and intrastrain variation in the numbers or positions of enzyme bands recorded among samples from different phases of culture growth or from different growth media. Similar differences were likewise noted among strains when they were sampled at the same growth phase. Hierarchical clustering and multidimensional analyses of the data produced groupings of the bacterial strains which suggested that their enzyme patterns were influenced by factors related to their geographic distribution or their animal host origins.