Study on biofiltration capacity and kinetics of nutrient uptake by Gracilaria cervicornis (Turner) J. Agardh (Rhodophyta, Gracilariaceae)

ABSTRACT

The absorption efficiency and kinetic parameters (Vmax, Ks and VmaxKs) of the seaweed Gracilaria cervicornis for the nutrients NH4+, NO3- and PO4(3-) were evaluated. Absorption efficiency was measured by monitoring nutrient concentrations for 5 h in culture media with initial concentrations of 5, 10, 20 and 30µM. Kinetic parameters were determined by using the Michaelis-Menten formula. Absorption efficiencies for this algae were greater in treatments with lower concentrations, as evidenced by a reduction of 85.3, 97.5 and 81.2 percent for NH4+, NO3- and PO4(3-), respectively. Kinetic parameters show that G. cervicornis exhibits greater ability to take up high concentrations of NH4+ (Vmax=158.5µM g dw-1 h-1) and low concentrations of PO4(3-) (Ks=5µM and VmaxKs=10.3). These results suggest that this algal species has good absorption capacity for the nutrients tested and may be a promising candidate as a bioremediator of eutrophized environments.