Bacteriological and biochemical relationships in the pyocyaneus-fluorescens group

Abstract

B. pyocyaneus, B. fluorescens liquefaciens and B. fluores-cens non-liquefaciens together with 100 green fluorescent strains isolated from nature, show a remarkably close relationship both morphologically and culturally. The chromogenic function in this group is apparently considerably more constant than are the usual characteristics on which bacterial classification is based. On glycerol 5%, peptone 2%, agar 3%, the typical strain of B. pyocyaneus produces blue pyocyanin abundantly, but forms no fluorescent pigment. In NH4NO3 0.1%, K2HPO4 0.025%, MgSO4.7H2O 0.025%, EtOH 0.1%, B. pyocyaneus gives an intense green fluorescence, but no pyocyanin. Traces of heavy metals, as in NH4NO3 0.1%, K2HPO4 0.025%, MgSO4.7H2O 0.025%, FeSO4.7H2O 0.0001%, EtOH 0.1%, completely inhibit pigment production. B. fluorescens gives no color with any of these media, while the natural strains divide sharply into 2 groups, corresponding with regard to their chromogenic properties to B. pyocyaneus and to B. fluorescens.