The microorganism
The microalga S. platensis was obtained from the culture collection
of algae at the University of Texas at Austin, USA,
(UTEX NO. LB 2340). It was propagated in the laboratory
and in the field according to the methods described by
Vonshak (1997) and Al-Homaidan (2002). Harvesting was
done by filtration through nylon filters (150–200 mesh). After
harvesting, S. platensis was rinsed with deionized water and
dried overnight in an oven at 80 C. The dried biomass was
ground well and sieved using a standard metal sieve (100 lm
pores) and stored in a desiccator to avoid moisture absorption.