Open AccessVertical distribution of nitrite reductase genes ( nir S) in continental margin sediments of the Gulf of Mexico
Author(s) -
Tiquia Sonia M.,
Masson Steven A.,
Devol Allan
Publication year - 2006
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2006.00173.x
Subject(s) - denitrifying bacteria , denitrification , biology , sediment , nitrite reductase , nitrate , oxygen minimum zone , anoxic waters , continental margin , oceanography , ecology , nitrogen , nitrate reductase , geology , paleontology , upwelling , chemistry , tectonics , organic chemistry
Abstract Marine sediments account for up to 66% of the loss of nitrogen load to coastal areas. Sedimentary denitrification is the main sink for fixed nitrogen in the global nitrogen budget, and thus it is important to understand the structure and composition of denitrifying communities. To understand the structure and composition of denitrifying communities, the diversity of nitrite reductase ( nir S) genes from sediments along the Gulf of Mexico was examined using a PCR‐based cloning approach. Sediments were collected at three different depths (0–0.5, 4–5 and 19–21 cm). Geochemical analysis revealed decreasing nitrate and oxygen concentrations with increasing sediment depth. This trend coincided with the decrease in diversity of denitrifying bacteria. LIBSHUFF analysis indicated that the clone library in the shallowest sediment (depth, 0–0.5 cm) was significantly different from that in the deepest sediment (depth, 19–21 cm), and that the deeper sediments (depths of 4–5 and 19–21 cm) were significantly similar. Community structural shifts were evident between the shallowest (oxic zone) and deepest (anoxic zone) sediments. Community changes within the deepest sediments were more subtle, with the presence of different nir S clone sequences gradually becoming dominant or, alternatively, decreasing with depth. The changes in community structure at this depth are possibly driven by nutrient availability, with lower quality sources of carbon and energy leading to the disappearance of nir S sequences common in the top layer. The majority of recovered nir S sequences were phylogenetically divergent relative to known denitrifying bacteria in the database.