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

A statistical approach was employed to assess microbial community variabili ty within a single 4-1 water sample and among 10 independent 4-1 water samp les from a single location using community-level physiological profiles. Po wer calculations demonstrated that duplicate analyses could distinguish bet ween two different locations at two times during the year. Variability asso ciated 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-si te differences at alpha = 0.05 with power exceeding 0.95 at both times of t he year. Similar methods are recommended to determine the appropriate numbe r of replicates for environments of interest. (C) 2000 Federation of Europe an Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.