J. M. Wells

Determination of Fatty Acid Profiles Relevant to the Characterization of Erwinia Amylovora

A total of 143 isolates of Erwinia amylovora from various rosaceous host plants were collected from 5 states and 10 foreign countries. The isolates were grown on trypticase soy broth with agar added for determination of the cellular fatty acids composition of the bacteria. Extracts were prepared by saponification of whole bacterial cells, followed by acidification of the solution, liberation of the fatty acids, and subsequent gas liquid chromatography analysis. Fatty acid peaks were identified by a computer-calculator. The most abundant fatty acids were straight-chain 12:0, 14:0 and 16:0; unsaturated 16:1 and 18:1; and 14:0 30H and 17:0 cyclopropane. Minor fatty acids included straight-chain 15:0, 17:0 and 18:0. The saturated even-carbon chains comprised about 49%, the unsaturated acids 28, cyclic acids 10, hydroxy substituted chains 9%, and saturated odd-carbon chains 1% of total fatty acids. The highest standard deviation was obtained on the unsaturated and cyclic fatty acids. Fatty acid class nalysis indicated relative uniformity within the E. amylovora group. A slight variation in the percentage cyclic acids was observed in isolates obtained from Belgium vs. those from England and the USA, as well as in isolates from Rubus vs. those from Pyrus, Crataegus and Cotoneaster.