Abundance and Diversity of Denitrifying and Anammox Bacteria in Seasonally Hypoxic and Sulfidic Sediments of the Saline Lake Grevelingen.
Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity, and potential activity of denitrifying, anammox, and sulfide-dependent denitrifying bacteria in the sediments of the seasonally hypoxic saline Lake Grevelingen, known to harbor an active microbial community involved in sulfur oxidation pathways. Depth distributions of 16S rRNA gene,nirSgene of denitrifying and anammox bacteria,aprAgene of sulfur-oxidizing and sulfate-reducing bacteria, and ladderane lipids of anammox bacteria were studied in sediments impacted by seasonally hypoxic bottom waters. Samples were collected down to 5 cm depth (1 cm resolution) at three different locations before (March) and during summer hypoxia (August). The abundance of denitrifying bacteria did not vary despite of differences in oxygen and sulfide availability in the sediments, whereas anammox bacteria were more abundant in the summer hypoxia but in those sediments with lower sulfide concentrations. The potential activity of denitrifying and anammox bacteria as well as of sulfur-oxidizing, including sulfide-dependent denitrifiers and sulfate-reducing bacteria, was potentially inhibited by the competition for nitrate and nitrite with cable and/orBeggiatoa-like bacteria in March and by the accumulation of sulfide in the summer hypoxia. The simultaneous presence and activity of organoheterotrophic denitrifying bacteria, sulfide-dependent denitrifiers, and anammox bacteria suggests a tight network of bacteria coupling carbon-, nitrogen-, and sulfur cycling in Lake Grevelingen sediments.
Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research, Utrecht University Den Burg, Netherlands.
Yvonne A
YA
Lipsewers
Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research, Utrecht University Den Burg, Netherlands.
Ellen C
EC
Hopmans
Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research, Utrecht University Den Burg, Netherlands.
Filip J R
FJ
Meysman
Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research, Utrecht UniversityDen Burg, Netherlands; Faculty of Geosciences, Department of Earth Sciences, Utrecht UniversityUtrecht, Netherlands.
Jaap S
JS
Sinninghe Damsté
Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research, Utrecht University Den Burg, Netherlands.
Laura
L
Villanueva
anammox bacteria; aprA gene; denitrifiers; intact polar lipids (IPL); ladderane lipid; nirS gene; sulfide-oxidizing bacteria