THE EFFICACY IN VIVO OF ERWINIA HERBICOLA ANTIBIOTICS IN INHIBITING ERWINIA AMYLOVORA

Erwinia herbicola produces antibiotics that inhibit E. amylovora in vitro. Many of these antibiotics are not toxic in the presence of one or more amino acids.
Strains of E. herbicola that produce an antibiotic not toxic in the presence of histidine (histidine-type) were far more effective in protecting immature pear fruits from fire blight than were strains producing an alanine-type antibiotic.
This could result from the fact that pear juice is low in histidine but rich in alanine.
The protection of pear fruits by E. herbicola producing the histidine-type antibiotic was reduced when the pears were supplemented with histidine or the E. amylovora was resistant to the antibiotic.
These results are consistent with the hypothesis that the histidine-type antibiotic is effective in vivo because of the low concentration of histidine in pear.
The protection of pears by E. herbicola producing the alanine-type antibiotic was not affected by the addition of alanine or using an E. amylovora that was resistant to the antibiotic.
These results are consistent with the hypothesis that the alanine-type antibiotic is not effective in vivo because of the high concentration of alanine in pears.
Thus, the amino acid composition of the pear tissue affects the efficacy of the antibiotics.

VII International Workshop on Fire Blight

R.S. Wodzinski, C.A. Jock, L.M. Wilson

https://doi.org/10.17660/ActaHortic.1996.411.63