Evidence for bacterial urea production in marine sediments

Abstract

The quantitative importance of bacteria in urea production and turnover in a defaunated sediment from a Danish estuary was studied. After collecting the sediment, benthic infauna was removed by sieving, followed by anoxic pre-incubation for a week. Yeast extract was added to half of the samples. The urea concentration, urea production/turnover rates and the net ammonium production rate, were followed during a 338 h incubation. The urea concentration was highest in the enriched sediment, although urea production and turnover rates were the same in the enriched and control sediment, indicating that the urea concentration was controlled by the urea turnover rate constant, kttre a. Net ammonium production, urea concentrations and the urea turnover declined towards the end of the experiment. Comparison of the net ammonium production rate and the urea turnover rate in the enriched and control treatments, showed that urea hydrolysis accounted for up to 100% of the ammonium produced, from all sources. More than 98% of the urea which was hydrolyzed, originated from production during incubation. This suggests that urea was a major nitrogen excretion product from bacteria in this sediment, and that bacteria could also be an important source of urea in other marine sediments.

Effect of urea on growth and microcystins production of Microcystis aeruginosa

“…The (Glibert et al, 1982;Lund and Blackburn, 1989;Pedersen et al, 1993). Cyanobacteria and heterotrophic bacteria can convert urea-N to ammonium (NH 4 + ) via urea amidolyase (UALase), and also can regulate urease activity (Solomon et al, 2010).…”

Nitrogen Cycling in Sediments

“…Protein amino acids are an important source of ammonium in sediments, although estimates of their contribution vary widely, from about 25 to about 80 percent of ammonium production (Burdige and Martens 1988;Mayer and Rice 1992;Pantoja and Lee 2003). The rapid microbial turnover of urea suggests that RNA may also be an important source of ammonium in some sediments (Lomstein et al 1989;Pedersen et al 1993;Therkildsen et al 1996), while extracellular DNA has been estimated to account for 7 percent of nitrogen mineralization in deep-sea sediments (Dell'Anno and Danovaro 2005).…”

Urea Uptake and Carbon Fixation by Marine Pelagic Bacteria and Archaea during the Arctic Summer and Winter Seasons

“…In addition to riverine input, other natural sources of urea in the Arctic can include excretion and sloppy feeding by zooplankton (19) and inputs from the melting of seasonal fast ice (20). Urea production has also been attributed to sediment-associated bacteria, which may mediate the release of urea into the water column via thermal or wind-driven mixing (21). In the Canadian Arctic, urea has been observed to account for Ͼ50% of total dissolved nitrogen (TDN) (22).…”