THE DIFFERENTIATION OF PSEUDOMONAS FROM OTHER GRAM-NEGATIVE BACTERIA ON THE BASIS OF ARGININE METABOLISM

SUMMARY: Of 391 Gram-negative bacteria isolated from chicken meat spoiled at a low temperature and classified by the commonly used methods, 156 were considered to be Pseudomonas and 188 Achromobacter , and 47 others belonged to the coli-aerogenes group or remained unclassified. A test for the production of alkaline conditions in an arginine medium incubated under a vaseline seal gave positive results for 155 of the Pseudomonas isolates, and negative results for 1 Pseudomonas and all the 188 Achromobacter strains. When named strains from culture collections were tested under these conditions, 63 Pseudomonas strains produced alkalinity while two plant pathogenic Pseudomonas species and two non-pigmented strains did not. These last two, which produced no acid from glucose, could not be regarded as typical Pseudomonas. All the Achromobacter strains gave negative results, as did four Alcaligenes , but one species, Alcaligenes bookeri , produced slightly alkaline conditions. One strain of Chromobacterium and three of Vibrio were also positive. These could be distinguished from Pseudomonas by their metabolism of glucose.