Primary Production of Particulate Protein Amino Acids: Algal Protein Metabolism and its Relationship to the Composition of Particulate Organic Matter

摘要

The proportion of cellular carbon in protein and free amino acids of the marine chlorophyte, Nannochloris sp., decreased with decreasing growth rate during steady state NH(+4)-limitation. These compositional changes were reflected qualitatively in distributions of incorporated inorganic 14C, demonstrating its utility as a probe of algal metabolism. Synthesis rates of protein amino acids were estimated from their rates of incorporation of inorganic 14C in Nannochloris sp. under various conditions of NH(+4) and light limitation. Glycine and alanine in protein had the most rapid saturation kinetics and proved ideal model protein acids for estimating production rates of protein. Similar results were found for Chaetoceros simplex, Chattonella luteus, and Chroomonas salina. A significant difference was observed between the proportion of total POC (particulate organic carbon) production associated with PPAA (particulate protein amino acid) carbon production and the proportion of total POC in PPAA during the decline of a bloom in a marine pond. (Copyright (c) Steven Eric Lohrenz.)