Barley rhizobacterial population characterised by fatty acid pro®ling

The aim of the study was to explore the possibilities for using fatty acid analysis to characterise rhizobacterial populations. Fatty acid pro®les were determined for 1188 bacterial isolates originating from barley roots growing in three different soils, two of which were clays and one a silt loam. A multivariate statistical treatment of the fatty acid data revealed three distinct groups of rhizobacteria. For 720 isolates (Group A), almost the whole fatty acid content of the cell consisted of straight-chain fatty acids with an even number of carbon atoms in the chains. In another group (B) of 435 isolates, most of the fatty acids had branched chains with an odd number of carbon atoms. A small group (C) with 33 isolates was mainly characterised by high contents of the fatty acid 15 : 0 Anteiso. The dominating bacterial genera in these three groups were Pseudomonas, Cytophaga and Gram positives, respectively. When roots had grown in clay soils bacteria from Group A were most frequent, Group B dominated in the loam. # 1999 Elsevier Science B.V. All rights reserved.