AGROBACTERIUM TUMEFACIENS CONN I. Release of P 32 and S 35 in Vitro

Abstract

P32-labeled crown gall bacteria, when grown under a wide variety of cultural conditions in nonradioactive media, release large amounts of their p32. The release p32 appears to comprise many compounds. The amount of P32 present in the supernatant medium at any particular time is a reflection of 3 sets of factors: (a) time of sampling after inoculation, (b) physiological state of the bacteria in the labeled inoculum, and (c) cultural conditions under which the labeled bacteria are grown, particularly the composition of the nonradioactive media. Evidence is presented which indicates that the p32 release results from lysis of the bacteria. It is suggested that this lysis reflects the presence of lytic agents which are associated with the bacteria (e.g., bacteriophages). Five bacterial strains were investigated; all showed this p32 release. S^S-labeled bacteria release very little of their sulfur. It could be shown that the bacterial sulfur in this system behaves chemically quite differently from the bacterial phosphorus. No evidence was obtained which supports the view that crown gall bacteria, when grown in extracts obtained from previously wounded plant stems, release a specific deoxyribo-nucleic acid which acts as the tumor-inducing principle. There was no obvious correlation between P32 release and tumor-indue ing ability. Nor was any increase in P32 release noted when pathogenic, labeled bacteria were grown in plant extracts obtained from wounded plant-stem extracts.