COMPARISON OF SOLE CARBON SOURCE PROFILES MONITORED AT 2 DIFFERENT WAVELENGTHS

Profiles of sole carbon source utilization are increasingly used to ch aracterize microbial communities in various environments. Metabolizati on of a single carbon source is detected by monitoring a colorimetric reaction. In most work, either of two different wavelengths, 405 or 59 0 nm, has been employed for detection. In the present study we compare d the outcome of these two detection modes applied to a study of the i nfluence of plant growth-promoting rhizobacteria on the root-inhabitin g microbial communities on the roots of young tomato; plants, The resu lts showed different average well color development and number of posi tive wells when detected at the two wavelengths with respect to the de velopment of the single curve, absolute values and standard deviation. Further, the carbon source that was utilized the most by the rhizosph ere microflora was not congruent between the two reading modes. The ov erall results, however, were similar, as evaluated by multivariate sta tistics. Tn conclusion, this study indicates that the carbon source ut ilization profiles should be standardized with respect to the waveleng th used to enable comparability or development of models on the microb ial status in ecosystems. (C) 1998 Elsevier Science B.V. All rights re served.