Kinetics of uptake of phosphates and nitrates by marine multicellular algae Gelidium latifolium (Grev.) Born. et Thur.

Abstract

We studied nonstationary kinetics of the uptake of phosphates and nitrates by the red marine algae Gelidium latifolium (Grev.) Born et Thur. and calculated constants of the Michaelis-Menten equation for these elements. In the area of 0–3 μM, the kinetics of phosphate consumption had the following coefficients: maximum rate of uptake 0.8 μmol/(g h), constant of half-saturation 1.745 μM. For nitrate nitrogen at 0–30 μM, an adaptive strategy of uptake kinetics was noted with change of the equation parameters with time: after 1 h, the maximum rate of uptake was 5.1 μmol/(g h) and constant of half-saturation 19 μM, while within 2 h, the maximum rate of uptake significantly increased. This could be related to the synthesis of nitrate reductase. Coupled with the uptake of nitrates, nonstationary kinetics of the release of nitrates in the surrounding medium had a one-peak pattern: the maximum concentration of nitrites in the medium and the time of its achievement increased with the initial concentration of nitrates. The maximum concentration of nitrites was 6 to 14% of the initial concentration in the medium.