Quantify total biomass and assess shifts in microbial population

Phospholipid fatty acids (PLFA) are a main component of the cell membrane (essentially the skin) of all microbes. PLFA analysis provides direct information about a site’s microbial community in three key areas:

  • Viable (living) Biomass– Phospholipid fatty acids are a primary component of the membranes of all microbes. Because they decompose quickly upon cell death, total PLFA in a sample represents only the viable cells. An accurate measure of viable biomass is critical for evaluating the magnitude of existing and potential Microbial Induced Corrosion (MIC). Viable biomass numbers also provide a scale for dosage and affectiveness of Microbial Induced Corrosion (MIC) remediation .
  • Community Composition or Population “Fingerprint” – Many organisms produce specific or signature types of PLFA biomarkers allowing quantification of important MIC related groups (e.g. iron reducers, sulfate reducers, or fermenters). The relative proportions of these groups provides a fingerprint of a site’s microbial community which can then be used to evaluate microbial response to a particular treatment.
  • Microbial Activity – Some microbes, most notably Proteobacteria, modify specific PLFA biomarkers during periods of slow growth or in response to environmental stress. For example, cis monounsaturated fatty acids may be modified to cyclopropyl fatty acids during periods of slowed growth or modified to trans monounsaturated fatty acids to decrease membrane permeability in response to environmental stress. The ratio of product to substrate fatty acid thus provides an index of microbial health and metabolic activity.