OPTIMIZATION OF SOME HEAVY METALS BIOSORPTION BY REPRESENTATIVE EGYPTIAN MARINE ALGAE(1).

Marine algae-as inexpensive and renewable natural biomass-have attracted the attention of many investigators to be used to preconcentrate and biosorb many heavy metal ions. Impressed by this concept, the metal uptake capacity of Egyptian marine algae was examined using representatives of green and brown algae, namely, Ulva lactuca L. and Sargassum latifolium (Turner) C. Agardh, respectively. The biosorption efficiencies of Cu(2+) , Co(2+) , Ni(2+) , Cd(2+) , Hg(2+) , Ag(2+) , and Pb(2+) ions seem to depend on the type of the algae used as well as the conditions under which the uptake processes were conducted. It was demonstrated that a pH range of 7.5-8.8 was optimum for the removal of the tested metals. Similarly, the uptake process was markedly accelerated during the first 2 h using relatively low metal level and sufficient amounts of the dried powdered tested algae.

Studies on the application of immobilization technique for the production of cyclosporin A by a local strain of Aspergillus terreus.

The formation of cyclosporin A (Cy A) by immobilized spores and mycelia of Aspergillus terreus was investigated. Different carriers were tested as immobilizing carriers, whereby Ca-alginate was selected for further experimentation. The role of alginate concentration, biomass weight, pH value of the cultivation medium, repeated utilization of the immobilized fungus as well as the supplementation of different amino acid precursors were studied. Best Cy A outputs were attained with Ca-alginate 3% (w/v), mycelial weight 15% (w/v), pH 4.5 and four repeated cycles. Similarly, the Cy A productivity was markedly accelerated in the presence of L-valine and L-valine and L-leucine mixture.

Role of some fermentation parameters on cyclosporin A production by a new isolate of Aspergillus terreus.

A local isolate of Aspergillus terreus was selected among different microorganisms as a new cyclosporin A (Cy A) producing culture. The formation of Cy A was investigated under different fermentation conditions (including selection of the cultivation medium, fermentation time course, inoculum nature, medium volume, agitation rate, pH value). Relatively high Cy A productivities were maintained when the fermentation process was carried out using a medium composed of (g/L): glucose, 50; bactopeptone, 10; KH(2)PO(4), 5; KCl, 2.5; pH 5.3, inoculated with 2% standard inoculum of 48 h age, shaken at 200 rpm for 10 days.