Molecular Characterization of Marine Fungi from Diverse Marine Sources

Grant Winners

Deans

Abstract

Previous research in the PI's laboratory has developed a database of uncultured bacterial and fungal rRNA sequences derived from several habitats, such as marine invertebrate hosts and deep and shallow marine sediments. This data has been used for baseline characterizations of microbial biodiversity, and has resulted in several publications and an online database of characterized marine isolates - www.hboi.edu/dbmr/dbmr_hbmmd.html.

The current project aims to build upon previous results, focusing specifically on marine fungal symbionts, which are relatively uncharacterized. Thus far we analyzed about 150 (~ 5%) marine fungal isolates of the HBOI Marine Microbe Culture Collection (HBMMCC). All of these fungi were derived from a marine invertebrate source host or marine sediments. The most common genera was Penicillium (21%), followed by Eurotium (17.6%), Cordyceps (12%), Aspergillus (12%), and Chromocleista (6%). However phylogenetic analysis with both large and small subunit (LSU, SSU) rRNA gene sequences suggested wider intracladal diversity. Several of these isolates have been screened for natural product biosynthesis. Thus the next major goal is to compare cultured isolate diversity with culture-independent diversity using similar rRNA based methods. The primary hypothesis underlying this work is that different habitats and hosts will yield fundamentally different profiles of marine fungi, many of which are still uncultivable. To this end, we will apply the following experimental goals: a) construct metagenomic libraries of fungal rDNA fragments from various marine sources and hosts, b) determine the DNA sequences of 50-100 clones from each library c) compare rDNA sequences among different hosts and with previously characterized pure isolate profiles d) add to the databases of marine microbial diversity, and e) train graduate and undergraduate students in molecular biodiversity research. Besides adding to marine fungal research, we also anticipate that novel data will continually be incorporated into the vital and ongoing Census of Marine Microbes (http://icomm.mbl.edu).