Utilization of inorganic and organic nitrogen by bacteria in marine systems
The relative contribution of various inorganic and organic forms of nitrogen to the nitrogen requirements of picoplankton was examined with /sup 15/N tracers. Size fractionation was used to measure uptake by <1-..mu..m size microorganisms, and inhibitors of protein synthesis were used to separate procaryotic from eucaryotic nitrogen uptake. Picoplankton utilized mainly ammonium and amino acids and only negligible amounts of nitrate and urea. Nearly all amino acid uptake was by procaryotes, while both procaryotes and eucaryotes utilized ammonium. About 78% of total ammonium uptake was by procaryotes, and a significant portion of this was due specifically to heterotrophic bacteria. Regeneration of ammonium was correlated with eucaryotic rather than procaryotic activity. Ammonium accounted for at least 20-60% of the summed ammonium plus amino acid utilization by bacteria. The results suggest that significant portion of ammonium uptake in the euphotic zone was by heterotrophic bacteria rather than solely by phytoplankton. This may invalidate the use of the Redfield C:N ratio for estimating rates of nitrogen assimilation in the euphotic zone from carbon assimilation rates.
- Research Organization:
- Univ. of Georgia, Athens, GA (United States)
- OSTI ID:
- 6586752
- Journal Information:
- Limnol. Oceanogr.; (United States), Vol. 31:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BACTERIA
BIOCHEMICAL REACTION KINETICS
NITROGEN 15
UPTAKE
NITROGEN COMPOUNDS
ALANINES
AMINO ACIDS
AMMONIUM COMPOUNDS
CYANOBACTERIA
GLYCINE
NITRATES
SEAWATER
UREA
AMIDES
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACIDS
HYDROGEN COMPOUNDS
ISOTOPES
KINETICS
LIGHT NUCLEI
MICROORGANISMS
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
REACTION KINETICS
STABLE ISOTOPES
WATER
550701* - Microbiology- Tracer Techniques