Submitted to: International Plant Growth Promoting Rhizobacteria Workshop
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 2000
Publication Date: N/A
Technical Abstract: Pseudomonas fluorescens strain 2-79 (NRRL B-15132) is a classic biological control agent which is known to produce phenazine-1-carboxylic acid (PCA) as its primary means of suppressing take-all disease of wheat. In addition to PCA, an unknown metabolite was discovered by thin-layer chromatography (TLC) in a defined liquid production culture of strain 2-79. The **1H and **13C nuclear magnetic resonance and electron impact mass spectra indicate the identity of the purified compound to be 2-acetamidophenol (AAP). Using reversed-phase high performance liquid chromatography (HPLC), the accumulations of AAP and PCA in cultures of strain 2-79 were measured to reach 0.05 g/L and 1 g/L, respectively. The accumulations of AAP and PCA in liquid cultures were linearly correlated (P<0.001), as shown by studies of cultures stimulated to yield varying levels of PCA by controlling levels of oxygen transfer, pH, and growth medium composition. In this study, oxygen limitation, a defined amino-acid-free medium, and neutral pH stimulated maximal production of both AAP and PCA. Furthermore, a mutant strain of 2-79 unable to produce PCA [2A40 2-79 (phz-)] did not accumulate AAP. These findings indicate that AAP and PCA are likely to share a common segment of pathway steps during biosynthesis. This is the first report of AAP production by the classic biological control strain P. fluorescens. Possible routes of AAP production are discussed relative to current knowledge of the phenazine biosynthetic pathway of strain 2-79.