Abstract
Certain virus-resistant mutants derived from a virus-sensitive strain of E. coli required accessory growth factors, although the parent strain is capable of full development in a medium containing inorganic N and dextrose. The 27 strains used in this study have apparently lost the ability to synthesize tryptophane. One strain required proline in addition to tryptophane. All of the tryptophaneless strains are resistant to virus 71 and sensitive to T5. That other factors in the synthetic capacity of the mutants differ from those of the parent strain is evidenced by the observation that organic as well as ammonia N is essential for full development of the mutant strains. In a medium containing adequate N sources, the addition of 0.25 7 of l([long dash])-tryptophane gives a development of 108 cells in 24 hrs.

This publication has 3 references indexed in Scilit: