Use of Direct and Indirect Immunofluorescence Tests for Identification of Xanthomonas campestris

Abstract

A comparison was made between direct and indirect immunofluorescence (IF) for rapid identification of X. campestris [isolated from crucifer seeds]. Eighteen strains of X. campestris, 5 of X. vesicatoria, 9 of Xanthomonas spp., 5 of nonidentified yellow-pigmented bacteria, 1 of Escherichia coli and 1 of Pseudomonas syringae were tested. For direct IF cells were stained with fluorescein isothiocyanate (FITC)-conjugated .gamma. globulin to bacterial ribosomes. For indirect IF bacterial cells were treated with antiserum or .gamma. globulin to ribosomes and stained with FITC-conjugated antirabbit globulin. The stained cells were observed by fluorescence microscopy. All strains of X. campestris tested by indirect IF were positive, and only X. vesicatoria cross-reacted with X. campestris. Indirect IF using antiserum to ribosomes is a useful method for quick identification of X. campestris.