Determination of Pseudomonas aeruginosa by Biochemical Test Methods

III. Utilization of Tween 80 by Pseudomonas aeruginosa

Abstract

A new synthetic medium consisting of 0.2% KH₂PO₄, 0.01% MgSO₄·7H₂O, 0.5% NaCl, 0.05% (NH₄)₂SO₄ and 1.0% Tween 80 was devised by the authors as a means of differentiating between Pseudomonas aeruginosa and related species of gram-negative rods. One loopful of an overnight nutrient agar culture of a test strain was inoculated into 1 ml of this media, and incubated at 37 C for 24 hr. All of the 38 test strains of P, aeruginosa showed visible growth in this media, being capable of utilizing Tween 80 as a sole carbon source, whereas strains of Aeromonas, Vibrio parahaemolyticus, Achromobacter sp., Proleus sp., Escherichia coli and Citrobacter sp. could not grow within a 24 hr incubation period, although longer incubation yielded a visible growth with some strains. A strain of P. fluorescens did not show any visible growth at 37 C, but did show a moderate growth after a 48 hr incubation at 18 C. Strains of Klebsiella and Enterobacter showed only slight growth after incubation at 37 C for 24 hr.