ANALYSIS AND INTERPRETATION OF COMMUNITY-LEVEL PHYSIOLOGICAL PROFILESIN MICROBIAL ECOLOGY

A rapid, community-level approach for assessing patterns of sole carbo n source utilization by mixed microbial samples has been used increasi ngly to study microbial community dynamics. The method involves direct inoculation of environmental samples into Biolog microtiter plates, a nd uses color formation from reduction of a tetrazolium dye to assess utilization of 95 separate sole carbon sources during a 2-7 day incuba tion period. This approach, called community-level physiological profi ling, has been effective al distinguishing spatial and temporal change s in microbial communities. Effective analysis of the multivariate pro files of carbon source utilization requires separation of effects caus ed by differences in inoculum density (i.e. overall rate of color deve lopment) from effects caused by differences in the types or activities of organisms present (i.e, relative rates, or pattern, of carbon sour ce utilization). Further experimental studies are required to better d efine what fraction of the original inoculum responds in the assay, an d if the profiles provide structural and/or functional information.