The Fluorescent Pigment of Pseudomonas fluorescens: Biosynthesis, Purification and Physicochemical Properties

TLDR

The biosynthesis of a yellow–green, fluorescent, water‑soluble pigment by *Pseudomonas fluorescens* occurs only under iron‑deficient conditions and is not directly affected by the organic carbon source. The pigment, a single ~1500‑Da species, forms a highly stable Fe³⁺ complex (K≈10³²), is purified in this form, and its alkaline lability generates decomposition products, indicating it functions as a desferrisiderophore.

Abstract

The biosynthesis of a yellow–green, fluorescent, water-soluble pigment by Pseudomonas fluorescens occurred only when the bacteria were iron-deficient and was not directly influenced by the nature of the organic carbon source. The pigment formed a very stable Fe3+ complex and was purified in this form. Pseudomonas fluorescens produced only one molecular species of fluorescent pigment; however, its lability under mild alkaline conditions led to the formation of several pigmented decomposition products. The spectral properties of the pure pigment, its molecular weight (1500 ± 75) and its stability constant for Fe3+ (of the order of 1032) were determined. Both its biosynthesis and its chemical properties (formation of a stable Fe3+ complex) suggest that the fluorescent pigment is a desferrisiderophore.