Marine toxin research reveals key biosynthetic pathways,opening the way for product discovery

Marine microbial eukaryotes, single celled plankton abundant  in world oceans, drive global climatic processes, nutrient cycling and primary production. Scientists are especially interested in better understanding those species that produce toxins associated with harmful algal blooms because of their detrimental impact on fisheries, aquaculture and human health. For the first time, a UTS led collaboration provides key answers to basic questions about key biosynthetic pathways in these diverse and complex taxa with broader implications for science in general.
Dr Gurjeet Kohli, lead author of the research, published in ISME says that the research findings are important not only for marine toxin research but also for research working on micro-algal biofuels and marine natural product discovery, especially in times when the discovery of powerful antibiotics is becoming rare.
Dr Kohli, a Research Fellow in UTS: C3’s Seafood Safety research program, explains that the team were able to investigate the presence of fatty acid (FAS) and polyketide synthase (PKS) genes using their own data as well as the vast data resource provided by the Marine Microbial Eukaryote Sequencing Project (MMETSP). This houses the first comprehensive genetic information on 210 marine microbial genera, encompassing most of the major eukaryote lineages.

“Fatty acids are the basic building blocks of eukaryotic cell membranes and are a primary source of fuel for the cell,” Dr Kohli says.

 “We identified for the first time the key genes involved in fatty acid synthesis pathway in 20 major phototrophic lineages of microbial eukaryotes. We also discovered a vast diversity of genes involved in polyketide (toxin) production in lineages of microbial eukaryotes known to form harmful algal blooms.”

Co-author Dr. Uwe John from the Alfred Wegner Institute added that  “relaxed selection pressure may have been involved in the evolution of PKS secondary metabolite genes, allowing rapid change based on functionality, compared to the functionally conserved FAS genes.”

 Associate Professor Shauna Murray, who heads the Seafood Safety research team at C3 says that the researchshows conclusively that “microbial eukaryotes possess different pathways for fatty acid and polyketide production which will allow for the development of detection tools for a broad range of harmful algal bloom toxins”.

“This includes those responsible for ciguatera fish poisoning, which effects more than 500,000 people each year.”

The research team believe the findings are a significant step forwards for research in this field with broad implications for ecologists, microbiologists, biochemists, geneticists, toxicologists.

 “The recognition of novel polyketide synthase pathways for example will facilitate the discovery of bioactive compounds such as the recently found potential anti-cancer agents from the brevetoxin-producing dinoflagellate Karenia brevis. Microalgal fatty acids are undergoing intense research efforts currently due to their potential as biofuels, and our study identifies the key pathway in all microalgal lineages, enabling targeted research on as yet unstudied lineages," concluded the research team consisting of Assoc. Prof Shauna Murray and Dr. Gurjeet Kohli from UTS:C3, Dr. Uwe John from Alfred Wegner Institue, Germany and Dr. Frances M. Van Dolah from NOAA, United States.

Research funding:
Australian Research Council, Australian Academy of Science Germany-Australia Award, Alfred-Wegener Institute, NOAA

Publication details:

Evolutionary distinctiveness of fatty acid and polyketide synthesis in eukaryotes

Gurjeet S Kohli, Uwe John, Frances M Van Dolah and Shauna A Murray

ISME J advance online publication, January 19, 2016; doi:10.1038/ismej.2015.263