Isotopic fractionation of nitrogen and carbon in the synthesis of amino acids by microorganisms

摘要: Abstract Two classes of procaryotic organisms were cultured on specific inorganic and organic nitrogenous substrates. The fractionated these substrates in characteristic ways during the synthesis their cellular biochemical compounds. Blue-green algae, Anabaena sp., raised molecular nitrogen, nitrate ammonia presence excess carbon dioxide. difference between δ15N either or ammonium algae grown source was 13%o. that fixed N2 2% lighter than nitrogen gas supplied to algae. These fractionations are associated with enzymatic incorporation into cell. A heterotrophic bacterium, Vibrio harveyi a single amino acid as its both carbon. Cells glutamic enriched 15N relative substrate, whereas those alanine depleted compared nitrogen. bacterial cultures 13C substrate. then hydrolyzed individual acids isolated isotopically analyzed. isotopic compositions have wide range values; most appear isotope metabolic pathways synthesis. results application coupled separation-isotopic analysis yield better understanding comparative biochemistry for organisms. Such analyses offer valuable information tracing biosynthesis early diagenesis help explain fossil record.