THE CONTRIBUTION OF INDIVIDUAL POPULATIONS TO THE BIOLOG PATTERN OF MODEL MICROBIAL COMMUNITIES

Model microbial communities consisting of 2 or 3 bacterial strains wer e used to validate the Biolog system as a tool for microbial community analysis. The a priori known taxonomical structure and carbon substra te utilization pattern of the separate community members allowed the d etection and analysis of the contribution of the individual population s to the whole-community patterns. All the whole-community Biolog patt erns were dominated by the fastest growing strain, even when this stra in represented only 10% of the total inoculated cell numbers, and ther e was evidence that the activity of the slowest growing member of the model community was partially mask-ed by the other ones. However, diff erentiation of these closely related microbial communities was still p ossible with principal component analysis, provided that the incubatio n time was well chosen. The problem of choosing the right incubation t ime was overcome by the use of the parameters of the Gompertz equation , which was fitted to the color development in each Biolog well. These kinetic parameters were independent of the incubation time and still allowed a clear separation of the closely related model communities by means of principal component analysis. This approach is proposed as a n alternative way for processing Biolog data in microbial community an alysis.