Genetic and Biochemical Characteristics of Six Phytopathogenic Species of Pseudomonas

Abstract

1. The five toxigenic and one non-toxigenic species of Pseudomonas differed with respect to three characteristics: (a) the relative frequency of nutritionally deficient mutants obtained by irradiating cells with ultraviolet light and the spectrum of mutants with specific requirements, (b) growth or lack of growth of methionine-requiring mutants when a number of organic sulfur-containing compounds were added to the defined medium, and (c) Rf value of exotoxins obtained from the toxigenic species. 2. Mutation rates from sensitivity to resistance to streptomycin were not significantly different for the six species; streptomycin-resistant mutants were toxigenic. 3. Growth of P. tabaci in media containing 6 x 10-3 M allylglycine, an antimetabolite for cysteine, provided an in vitro test to distinguish this species from P. angulata, which was inhibited in growth. 4. The relation between P. tabaci and P. angulata was briefly discussed on the basis of the simulation of the latter species by non-toxigenic variants...