title: Quantitative determination of microbial activity and community nutritional status in estuarine sediments:  evidence for a disturbance artifact.
abstract: In estuarine sediments with a high degree of vertical heterogeneity in reduced substrate and terminal electron acceptor concentrations, the method of exposure of the microbiota to labeled substrates can introduce a "disturbance artifact" into measures of metabolic activity.  The detection of this artifact is based on quantitative measurement of the relative rates of incorporation of [14C]acetate into phospholipid fatty acids (PLFA) and endogenous storage lipid, poly-beta-hydroxyalkanoate (PHA).  Previous studies have shown that PLFA synthesis measures cellular growth and that PHA synthesis measures carbon accumulation (unbalanced growth).  The "disturbance artifact" of exposure to [14C]acetate was demonstrated by comparing injection of a core with the usual or pore-water replacement or slurry techniques.  Only injection of labeled substrate allowed detection of preassay disturbance of the sediment with a garden rake.  The raking increased PLFA synthesis with little effect to differences in concentration or distribution of [14C]acetate in the 10-min incubation.  Bioturbation induced by sand dollar feeding in estuarine sediment could be detected in an increased PLFA/PHA ratio which was due to decreased PHA synthesis if the addition of labeled substrate was by the injection technique.  Addition of labeled precursors to sediment by slurry or pore-water replacement induces greater disturbance artifacts than injection techniques.
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee 32306, USA.
authors.forename: R H
authors.initials: RH
authors.lastname: Findlay
authors.forename: P C
authors.initials: PC
authors.lastname: Pollard
authors.forename: D J
authors.initials: DJ
authors.lastname: Moriarty
authors.forename: D C
authors.initials: DC
authors.lastname: White
mesh_terms: D000085:Acetates / Q000493:pharmacokinetics; D000818:Animals; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D018533:Biomass; D002250:Carbon Radioisotopes; D004269:DNA, Bacterial; D004783:Environmental Microbiology; D005227:Fatty Acids / Q000032:analysis / Q000096:biosynthesis; D005431:Florida; D019015:Geologic Sediments / Q000032:analysis* / Q000737:chemistry / Q000382:microbiology*; D006885:Hydroxybutyrates / Q000032:analysis / Q000378:metabolism; D008055:Lipids / Q000032:analysis / Q000096:biosynthesis*; D008828:Microbiological Techniques; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000032:analysis / Q000096:biosynthesis*; D011091:Polyesters / Q000032:analysis / Q000378:metabolism; D011235:Predatory Behavior; D012617:Sea Urchins; D013936:Thymidine / Q000493:pharmacokinetics; D000094122:Polyhydroxybutyrates
chemical_list: D000085:Acetates; D002250:Carbon Radioisotopes; D004269:DNA, Bacterial; D005227:Fatty Acids; D006885:Hydroxybutyrates; D008055:Lipids; D010743:Phospholipids; D011091:Polyesters; D013936:Thymidine; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates