Paper No. 3
Presentation Time: 8:00 AM-12:00 PM
MEASURING THE DIVERSITY OF MYCOSPORINES AND MYCOSPORINE LIKE AMINO ACIDS (MAA) OF BOTH PROKARYOTIC AND EUKARYOTIC MICROORGANISMS FROM ROCK COMMUNITIES BY A NEW UNIVERSAL EXTRACTION METHOD
Mycosporines and mycosporine-like amino acids (MAAs) are water soluble pigments. They are synthesized by eukaroytic and prokaryotic organisms including zooplankton and phytoplankton, but are only found as secondary metabolites in terrestrial fungi and melanized human pathogens. The mycosporines and MAAs provide important UV protection to microorgnisms in high radiation habitats. They act as protective substances in both pro- and eukaryotic microorganisms. The major function of low molecular UV-B absorbing hydrophilic compounds is their capacity to act as photoprotective UV filters in prokaryotes, or to exercise a regulatory effect on sporulation in eukaryotes, such as microcolonial fungi (MCF). They also can serve as antioxidants and/or provide an osmoprotective function. The chemically labile mycosporines and MAAs on the rock surface are protected and preserved by either the presence of living cells or by physical and chemical interactions with the rock substrate itself. MCF, the primary emphasis of our study, contain melanin, mycosporines, carotinoids and possibly other unidentified pigments. We present here a new universal method for the extraction of mycosporines and MAAs. Pure cultures of microorganisms from terrestrial, marine and fresh water habitats have been studied, including eukaryotic fungi (ascomycetes, basidiomycetes, deuteromycetes) and prokaryotes (actinomycetes of the Geodermatophilus genus and various cyanobacteria). The microorganisms were screened for the content and diversity of mycosporines and MAAs along with natural stone samples such as marble and various sandstones. Extracts of both microorganisms and rocks were analysed, and the UV-B absorbing compounds were characterized. Extraction of the water soluble contents were then analysed using reverse-phase high performance liquid chromatography (HPLC) coupled with mass spectroscopy to quantify and identify the UV-B absorbing compounds. Five MAAs, eight mycosporines, and one as yet unidentified UV- absorbing substance were successfully extracted and separated by the new universal method.