Utilization of Biuret by Pseudomonas aeruginosa

Abstract

IN the course of investigating the dissimilation of biuret by micro-organisms, we found that all of seven strains of Pseudomonas aeruginosa examined were inducible for an enzyme, or enzyme system, capable of hydrolysing biuret. Den Dooren de Jong¹ isolated some 40 pseudomonads, only two of which showed good growth when biuret was provided as sole carbon, nitrogen and energy source. Although biuret does not seem to be a good nitrogen source for any of the strains which we examined, conditions eventually were achieved in which cell growth, using glucose as an energy source, was sufficiently fast and predictable for study. Biuret does not serve as the sole source of carbon and energy. The mean generation time in biuret media (Fig. 1) is characteristically about twice that observed in ureamedia under similar conditions; this relation is maintained when absolute growth-rates higher than those shown are obtained by increasing the aeration. The curves shown describe only about three generations; but growth curves followed by plate counts, and extending over some 20 generations, are in agreement with those presented; however, for smaller, unadapted inocula, the adaptation is more erratic, and the curves cannot at present be analysed with confidence.