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V. Martin-Jézéquel, A. Sournia, J.-L. Birrien, A daily study of the diatom spring bloom at Roscoff (France) in 1985. III. Free amino acids composition studied by HPLC analysis, Journal of Plankton Research, Volume 14, Issue 3, 1992, Pages 409–421, https://doi.org/10.1093/plankt/14.3.409
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Abstract
The growth of a natural phytoplankton population was studied during a monospecific spring bloom of the diatom Rhizosolenia delicatula at Roscoff (western English Channel). Direct examination of the intracellular pool of 19 free amino acids (FAA) was used as an index of the physiological status of the cells. Total FAA in the particulate matter shows a general decrease during the bloom, and FAA cell content varies from 200 mM 1 cell volume−1 to 10 mM at the time of maximum biomass. FAA-N/particulate N is <3% during the study, slightly decreasing at the time of maximum biomass. Individual free amino acids appear reliable for the development of the diatom biomass and good indicators of the growing population. At maximum biomass, major compounds are glutamic acid (30.8 mol%), glutamine (11.7%), alanine (9.9%), isoleucine (6.6%) and lysine (6.4%). Serine, glycine, arginine and aspartic acid appear also as major components during other periods of the study. We suggest that the observed changes are an indication of the physiological state of the cells during the bloom. In particular glutamine (GLN), glutamic acid (GLU) and the GLN/GLU ratio allow the metabolic evolution of the natural population to be characterized. GLN is strictly linked to the living biomass (Chla) while GLU is present at high percentage throughout the study. The ecological significance of β-alanine (BALA) is also revealed during this study, being strongly correlated to degraded matter represented by phaeopigments. These results demonstrate the validity of using individual free amino acids as an aid in understanding the physiological status of algae in natural bloom conditions.
