Dissolved free amino acids in the marine environment: a carbon to nitrogen ratio shift during diatom blooms

Concentration and variation of 16 free amino acids were measured in the internal and external pools of 11 marine phytoplankton species belonging to 5 taxonomic classes in culture. Changes detected in each pool were related to both the species, classes and phases of growth. The intracellular and extracellular pools had a different con~position. The internal pool was characterized by aspartic acid, glutamic acid, serine, glutamine and leucine, which accounted for > 7 0 % of the total concentration. The extracellular pool was characterized by senne, glycine, leucine and lysine, accounting for >?O "10 of the total concentration. The proportions and combinations of these compounds were variable and enabled the species and classes of phytoplankton to be grouped according to their internal and external amino acids content. The abundance and flux of free amino acids seem to be related to both the size, biomass and metabolic activity and the growth conditions of the phytoplankton.

Section: Discussionmentioning

confidence: 99%

Interspecific and intraspecific composition and variation of free amino acids in marine phytoplankton

Martin‐Jézéquel¹,

Poulet²,

Harris³

et al. 1988

“…Growing phytoplankton cells release minimal amounts of amino acids, but amino acids are released by senescent cells during post-bloom conditions (Hammer e t al. 1981, Poulet & Martin-Jezequel 1983, Hammer & Eberlein 1986, Hammer & Kattner 1986. DFAAs c a n ongin a t e from faecal pellets a wide spectrum of amino aclds.…”

Section: Discussionmentioning

confidence: 99%

Responses of copepods to dissolved free amino acids

Gill¹,

Poulet²

1988

ABSTRACT. The first maxilla (Ml) beating frequency of Temora longicornis, which is considered to be an index of feeding behaviour, was measured using a computerized micro-impedance technique, in filtered seawater as a control, and after exposure to 9 different particle-free mixtures of equimolar (10-' M) amino acids dissolved in seawater. Mixtures containing 20 dissolved free amino acids (ASP, GLU,

“…Conclusions (0) and crihcisms or problems (e) are given; further comment will be found in the text (Table l b ) . However, its presence has been associated with grazing activity at other stations (Palumbo et al 1983, Hammer & Kattner 1986, Williams & Poulet 1986). Concentrations of individual amino acids, and of total DFAA, vary with time of day, season, depth and location (Mopper & Lndroth 1982, Braven et al 1984, Poulet et al 1984, Williams & Poulet 1986.…”

Section: Urea and Trimethylammonium Oxidementioning

confidence: 99%

Nitrogen sources for the growth of marine microalgae: role of dissolved free amino acids

Flynn¹,

Butler²

1986

170

108

Dissolved free amino acids (DFAA) form a significant proportion of dissolved fixed nitrogen in marine waters and could provide an additional source of nitrogen for the growth of marine microalgae. With the advent of DFAA analysis by HPLC, recent studies of algal physiology, and an increased awareness of potential experimental errors, doubts are cast over the conclusion that marine microalgae are not net users of DFAA. Results obtained by testing the use of a few amino acids cannot be extrapolated; the full range of amino acids should be used in field experiments. A high rate of uptake of any one amino acid is not to be expected. It is more probable that a simultaneous uptake of several amino acids will occur at a lower rate. It is essential that environmental conditions be taken into account in interpretation of results from field experiments. Results from laboratory and field studies suggest that maximum rates of DFAA uptake would occur in dark conditions in waters depleted of dissolved inorganic nitrogen. Turbid estuaries and coastal waters would also be environments likely to induce a significant uptake of amino acids, because levels of nFA.4 i.n. sl~ch WB!P~S S~C :~!st;l.~.~!y high and the periods of enforced darkness due to turbidity are likely to induce the development of microalgal amino acid uptake systems.