Institute for Applied Microbiology, University of Tennessee, Knoxville, Tennessee 37932, and Department of Plant Pathology and Biotechnology Center, The Ohio State University, Wooster, Ohio 44691.
Appl Environ Microbiol. 1989 Jun;55(6):1368-74. 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 conducive medium. Cucumber roots from the suppressive medium had higher proportions of cis-vaccenic acid (18:1 omega 7c) and the iso-branched monoenoic fatty acid i17:1 omega 8 but lower proportions of several iso- and anteiso-branched fatty acids compared with roots from the conducive 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, i17:1 omega 8, 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 18:1 omega 7c, not present in the lipids of the antagonist, indicating a shift in the microflora from a conducive to a suppressive bacterial community.
对在树皮堆肥介质中生长的黄瓜根系（Cucumis sativus L.）以及周围土壤基质的研究表明，这些根系中存在的极性脂脂肪酸图谱与细菌中常见的脂肪酸图谱相似。在自然抑制立枯丝核菌枯萎病的介质中生长的根系与在促进生长的介质中生长的根系的脂肪酸图谱组成有显著差异。与在促进生长的介质中生长的根系相比，来自抑制性介质的黄瓜根系具有更高比例的顺式vaccenic 酸（18:1 ω7c）和异分支单烯酸 i17:1 ω8，但几种同分支和 anteiso 分支脂肪酸的比例较低。周围介质中的细菌脂肪酸浓度明显较低。然而，抑制性和促进性生长基质中的细菌脂肪酸组成存在差异，与黄瓜根系本身的差异相似。这些结果表明，抑制性和促进性系统之间的细菌群落组成存在重大差异。脂肪酸分析也用于研究黄瓜根际定殖黄单胞菌（Flavobacterium balustinum 299）对细菌群落组成的影响，该菌是一种生物防治剂。在所处理的介质中，该细菌最显著脂肪酸 i17:1 ω8 的浓度在接种种子产生的根中增加，这与拮抗剂脂质中不存在的 18:1 ω7c 浓度显著增加相一致，表明微生物群从促进性向抑制性细菌群落发生转变。
