Comparison of sole carbon source profiles monitored at two different wavelengths

Abstract

Profiles of sole carbon source utilization are increasingly used to characterize microbial communities in various environments. Metabolization of a single carbon source is detected by monitoring a colorimetric reaction. In most work, either of two different wavelengths, 405 or 590 nm, has been employed for detection. In the present study we compared the outcome of these two detection modes applied to a study of the influence of plant growth-promoting rhizobacteria on the root-inhabiting microbial communities on the roots of young tomato plants. The results showed different average well color development and number of positive wells when detected at the two wavelengths with respect to the development of the single curve, absolute values and standard deviation. Further, the carbon source that was utilized the most by the rhizosphere microflora was not congruent between the two reading modes. The overall results, however, were similar, as evaluated by multivariate statistics. In conclusion, this study indicates that the carbon source utilization profiles should be standardized with respect to the wavelength used to enable comparability or development of models on the microbial status in ecosystems.