Determining replication for discrimination among microbial communities in environmental samples using community-level physiological profiles

A statistical approach was employed to assess microbial community variability within a single 4-1 water sample and among 10 independent 4-1 water samples from a single location using community-level physiological profiles. Power calculations demonstrated that duplicate analyses could distinguish between two different locations at two times during the year. Variability associated with replicates from a single container ol from different containers was nearly the same for the two sites examined. Duplicate assays (one from each of two independent samples) were sufficient to resolve the between-site differences at alpha = 0.05 with power exceeding 0.95 at both times of the year. Similar methods are recommended to determine the appropriate number of replicates for environments of interest. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.