S.A.I. Wright, S.V. Beer
Pantoea agglomerans strain Eh318 has been effective in biological control tests against fire blight and it inhibits the growth of Erwinia amylovora on minimal media. A double zone of inhibition on a plate containing a soft-agar overlay seeded with E. amylovora suggests the action of two distinct antibiotics, pantocin A and pantocin B. The structural characterization of pantocin A is underway, whereas that of pantocin B has been determined to be (R)-N-[((S)-2-Amino-propanoylamino)-methyl]-2-methanesulfonyl-succinamic acid. Subcloning and transposon mutagenesis data suggested that the genetic region involved in the biosynthesis of pantocin A is 2.7 kb at most, while that of pantocin B is at least 18.5 kb. The open reading frames (ORF) found within the pantocin A biosynthetic region were designated paaA, paaB and paaC. There is also a small ORF present upstream of the paaABC operon. The genes of the operon are similar in organization and, in the case of paaA, in DNA sequence to those involved in microcin C7 biosynthesis in Escherichia coli. Sequencing of the 18.5 kb biosynthetic region for pantocin B has commenced. Results thus far indicate that the region contains genes with putative amino acid sequence similarity to enzymes involved in the biosynthesis of and resistance to other antibiotics. Marker-exchange mutants of Eh318 deficient in the production of pantocin A (Eh421; PanA-), pantocin B (Eh439; PanB-) or both antibiotics (Eh440; PanAB-) were created. Strain Eh440 (PanAB-) was only marginally less effective than Eh318 in several immature pear fruit tests.
Wright, S.A.I. and Beer, S.V. (2002). GENES FOR BIOSYNTHESIS OF PANTOCIN A AND B BY PANTOEA AGGLOMERANS EH318. Acta Hortic. 590, 237-241
DOI: 10.17660/ActaHortic.2002.590.34
Erwinia herbicola, antibiotic, biocontrol, biological control, fire blight, Erwinia amylovora, Rosaceae

Acta Horticulturae