Genetic Detection of Marine and Estuarine Bacterial and Algal Communities Associated with Harmful Algae Blooms
Authors:Eric Izaguire, Jason Nefalar, Duan Nguyen, Theodore Peterson, Alicia Romero, Tiffany Sidwell
Mentor:James Harber, Professor of Microbiology, Oxnard College
Much of southern California’s coast is home to thriving bacterial communities capable of supporting growing numbers of detectable harmful algae blooms (HABs) that are responsible for poisoning of fish, seizures in marine mammals and both Amnesic and Paralytic Shellfish Poisoning in humans. The symbiosis between the algae and bacterial communities is predicated on an exchange of nutrients from nitrogen-fixing bacteria, including those of the genus, Vibrio. Seawater samples collected from several shoreline sampling points along the Southern California Bight were analyzed via real time PCR and shown to contain relevant isolates of both bacterial and phytoplankton species, including Vibrio parahemolyticus, the neurotoxin producing dinoflagellate, Lingulodinium polyedrum, and diatoms of the genus Psuedo-nitzschia. Bacterial isolates were also proven to be carriers of the beta- lactamase (ampicillin resistance) gene through real time PCR, suggesting that horizontal gene transfer between aquatic and terrestrial bacterial communities is likely. Genetic detection of the toxic algae species was accomplished via a protocol of: i) seawater collectioin and filtration ii) DNA extraction, purification, and quantitation iii) real time PCR amplification of indicative genetic sequences using species specific primers. Bacterial isolates were prepared in largely the same manner, with additional selection and isolation achieved by plating on MacConkey’s agar, replica plating onto ampicillin tryptic soy agar, and single colony isolation. This provided the starting material for the DNA extraction and real time PCR. Amplified 16S rRNA and ampicillin resistance sequences were quantified and sequenced allowing identification of the bacterial isolates by BLAST submission with confirmation, via traditional microbiology techniques. Further investigation of bacterial communities and an expansion of this research may provide a basis for the utilizing genetic markers of indicator species to detect HABs and their correlative bacterial communities.