Maintenance of a stock culture of by subculture on nutrient agar plates resulted in dissociation of the culture manifest as the development of fimbriate outgrowths from the initially entire peripheries of confluent streaks and isolated colonies. Auxanographic determination of minimal amino acid requirements of the dissociated culture indicated that it was composed of at least two types of organism: one was sensitive to (i.e. probably lysed by) L-lysine and the other resistant. They were further separated on the basis of sensitivity to lysine and colonial morphology into six different types. The microscopic appearance of organisms and their arrangement within colonies indicated that the original culture and each of the variants was a rough (R) type. At 28°, four variants required only L-glutamate for growth, while the remaining two required L-cysteine or L-α-alanine in addition. At 35° a greater number of amino acids had to be supplied for growth to occur. At neither temperature did the variants show a requirement for growth factors of the vitamin B-complex. These nutritional requirements, together with infrared spectra of whole organisms and biochemical characteristics determined by conventional methods, confirmed that each variant, though showing minor differences, did represent a culture of On auxanographic plates in the presence of L-lysine at 28°, three variants were lysed, one was unaffected, and the growth of two enhanced.


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