Microbial Community Composition and Denitrifying Enzyme Activities in Salt Marsh Sediments

Abstract

Denitrifying microbial communities and denitrification in salt marsh sediments may be affected by many factors, including environmental conditions, nutrient availability, and levels of pollutants. The objective of this study was to examine how microbial community composition and denitrification enzyme activities (DEA) at a California salt marsh with high nutrient loading vary with such factors. Sediments were sampled from three elevations, each with different inundation and vegetation patterns, across 12 stations representing various salinity and nutrient conditions. Analyses included determination of cell abundance, total and denitrifier community compositions (by terminal restriction fragment length polymorphism), DEA, nutrients, and eluted metals. Total bacterial (16S rRNA) and denitrifier (nirS) community compositions and DEA were analyzed for their relationships to environmental variables and metal concentrations via multivariate direct gradient and regression analyses, respectively. Community composition and DEA were highly variable within the dynamic salt marsh system, but each was strongly affected by elevation (i.e., degree of inundation) and carbon content as well as by selected metals. Carbon content was highly related to elevation, and the relationships between DEA and carbon content were found to be elevation specific when evaluated across the entire marsh. There were also lateral gradients in the marsh, as evidenced by an even stronger association between community composition and elevation for a marsh subsystem. Lastly, though correlated with similar environmental factors and selected metals, denitrifier community composition and function appeared uncoupled in the marsh.

Dispersion of TiO 2 Nanoparticle Agglomerates by Pseudomonas aeruginosa

“…The specific surface area of industrial TiO 2 (54 m 2 /g) was measured by the Brunauer-Emmett-Teller (BET) technique using a Tristar 3000 (Micrometrics, Norcross, GA). The specific surface area for laboratory-synthesized TiO 2 (94 m 2 /g) was calculated assuming spherical particles, uniform diameter (16 nm), and an estimated density of 3.97 g/cm 3 based on the weighted anataseto-rutile ratio. The zeta potentials for P. aeruginosa and industrial TiO 2 nanoparticles in LB media were Ϫ9.1 mV and Ϫ17.9 mV, respectively.…”

Review on the Fate and Mechanism of Nitrogen Pollutant Removal from Wastewater Using a Biological Filter

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Long-Term Effects of Multiwalled Carbon Nanotubes and Graphene on Microbial Communities in Dry Soil

“…The primers used for bacterial PCR were HEX-labeled 8F (AGA GTT TGA TCC TGG CTC AG) and 1492R (GGT TAC CTT GTT ACG ACT T). 39,40 The primers used for fungal PCR were FAM-labeled ITS1F (CTT GGT CAT TTA GAG GAA GTA A) and ITS4R (TCC TCC GCT TAT TGA TAT GC). 16,41 Each 0.5 mL reaction tube contained 50 μL of reaction mixture, containing 1× PCR buffer, 2.5 mM MgCl 2 , 0.2 mM of each dNTP, 0.2 μM of each primer, 1.5 U GoTaq DNA Polymerase (Promega, Madison, WI), 0.2 μg μL −1 bovine serum albumin (BSA), and 10 ng of template DNA.…”