Characterizing Microorganisms in the Environment by Fatty Acid Analysis

Determining the taxonomic composition, biomass, and physiological status of microbial assemblages is still one of the greatest challenges facing microbial ecologists. There are many reasons why assessment of microbes in the environment is so demanding, not least their number, diversity, and limited size. Unlike eukaryotes, descriptions of the morphology of prokaryotes usually yields little or no information concerning the phylogenetic affiliation or ecological role of organisms. Consequently, although direct observations can provide an indication of biomass, they do not allow the investigator to distinguish among the many microbial populations present in samples. Classical approaches that utilize enrichment methods for the isolation of microorganisms from the environment continue to provide valuable information in biochemical, taxonomic, and autoecological studies. The primary limitations to such approaches are those of nonculturability (the active cellular component that cannot be grown in the laboratory on artificial media), and the problem of characterizing and identifying statistically relevant numbers of isolates necessary to gain insight into the population ecology and community diversity of any but the simplest of habitats. Furthermore, these approaches rarely provide information on microbial assemblages in situ .