Characterization of bacteria that suppress Rhizoctonia damping-off in bark compost media by analysis of fatty acid biomarkers

• Published in: Applied and Environmental Microbiology 1989-06, Vol.55 (6), p.1368-1374
• Main Authors: Tunlid, A. (Lund University, Ecology Building, Helgonavagen, Lund, Sweden), Hoitink, H.A.J, Low, C, White, D.C
• Format: Article
• Language: English
• Subjects: ACIDE GRAS; ACIDOS GRASOS; AUXILIAIRE DE LUTTE BIOLOGIQUE; bacteria; Bacteriology; Biological and medical sciences; biological control; COMPOST; COMPOSTS; CORTEZA; CUCUMIS SATIVUS; damping-off; ECORCE; fatty acid composition; FLAVOBACTERIUM; Fundamental and applied biological sciences. Psychology; media; Microbiology; Microorganism-Plant Interactions; ORGANISMOS PARA CONTROL BIOLOGICO; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; RACINE; RAICES; RHIZOCTONIA; roots; TRAITEMENT DES SEMENCES; TRATAMIENTO DE SEMILLAS
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.55.6.1368-1374.1989

Examination of cucumber roots (Cucumis sativus L.) grown in bark compost media and of the surrounding edaphic substrate showed profiles of polar lipid fatty acids commonly found in bacteria. The composition of fatty acids in these profiles differed significantly between roots grown in a medium naturally suppressive to Rhizoctonia damping-off and roots from a conductive medium. Cucumber roots from the suppressive medium had higher proportions of cis-vaccenic acid (18:1omega7cis) and the iso-branched monoenoic fatty acid i17:1omega8 but lower proportions of several is- and anteiso-branched fatty acids compared with roots from the conductive medium. The concentrations of the bacterial fatty acids were significantly lower in the surrounding media. However, the suppressive and conducive growth substrates had differences in the composition of the bacterial fatty acids similar to those found between the cucumber roots proper. These results suggest major differences in bacterial community composition between suppressive and conducive systems. Fatty acid analyses were also utilized to examine the effects on bacterial community composition of root colonization by Flavobacterium balustinum 299, a biocontrol agent. The concentration of the most prominent fatty acid in this bacterium, i17:1omega8, was increased on roots produced from inoculated seeds in a medium rendered suppressive by the treatment. This change was concomitant with a significant increase in the concentration of 18:1omega7cis, not present in the lipids of the antagonist, indicating a shift in the microflora from a conducive to a suppressive bacterial community