Chemotaxonomy

This project was designed to investigate the effects of carbon dioxide (CO2) levels on the
growth and pigment ratios (chemotaxonomy) of freshwater algal species typical to the
south Florida surface waters. Green algae, diatoms, and cyanobacteria were cultured
under 400 or 800 ppm CO3 in air for several weeks. Growth monitoring used a cell
counter, hemocytometer, and chlorophyll fluorescence. Pigments were analyzed using
HPLC-PDA. Experiments with certified CO2 concentrations (400, 600, 800, 1200 ppm)
were conducted with helium degassed ultrapure water and each of three culture media.
Theoretical and experimental pH values with water matched exactly. However, each
culture media proved to exhibit significant buffer capacity. Cell growth monitoring was
problematic except for the cyanobacterium Microcystis aeruginosa. That species
responded to increased CO2 (800 ppm) with increased growth rates as predicted. The
other species gave erratic results mainly due to difficulties in obtaining valid consistent
cell counts.

Chemical analysis of large number of specimens of the sponge Xestospongia muta have revealed the existence of three distinct sterol chemotypes. Since sponges are well known to contain a diverse array of all classes of lipids, the utility of fatty acid composition as a chemotaxonomic tool for Xestospongia muta has been addressed. Further the biosynthetic capabilities of the three chemotypes are being evaluated for possible taxonomic use. Further the utility of TLC and NMR as additional taxonomic tools has also been evaluated.