TITLE: Natural Antibiotics from the Marine Environment (Phase IV)
AUTHOR: William M. Gordon
SCHOOL: Falmouth Academy
SCHOOL ADDRESS: 7 Highfield Drive, Falmouth, MA. 02540
The marine algae use din my project were collected from Seagull Beach in South Yarmouth, MA. Two different species of the red algal genus Polysiphonia were identified, during previous work, Phases I & II (P. denudata + P. nigens). Both were proved to have antibiotic properties against Staphylococcus aureus. This year’s work had three objectives, the first objective (Part 1) was to find out where the antibiotic is stored within the algea, the second objectie (Part 2) was to see if variation occurs in the antibiotic’s inhibition effect over time, and the third objective (part3) continued from Phase II, was an attempt to purify the antibiotic compound from the algae and determine it’s chemical structure.
The tests for part one, included grinding, laser irradiation, microwaving, freeze/thawing, and acetone dipping, all were meant to break the algae’s cell structure, releasing the antibiotic from different areas on the algae onto a Staphylococcus aureus seeded plate. The testing for part two, was done using the bioassay method. Ground algae was placed in wells made on chocolate agar plates, after the plate was seeded with Staphylococcus aureus. The plates were allowed to incubate at 32ºC and were then checked for an inhibition ring, which was measured using a cm. ruler. The testing for part three was done using solvent extractions following a method set by Tsuneynki and Yoshiaki Ando in 1955. After each solvent extraction and purification step, the new mixture was tested by bioassay with Staphylococcus aureus on chocolate agar plates.
The result for Part one, was that antibiotic is stored throughout both P. nigens and P. denudata in both the stems and the tips. The result for part two, was that the antibiotic effect of both P. nigens and P. denudata varies over time. The result for part three, was that the purification method was reproducible, but further purification is needed in order to successfully determine the chemical structure of the antibiotic from the algae.