Algal Biotechnology in the Gerwick Lab: From Pharmacy to Fuel

By R. Cameron Coates

 

Drs. Bill and Lena Gerwick

Dr. Bill and Dr. Lena Gerwick lead the Gerwick lab and have developed an effective style that builds on their respective strengths in chemistry, molecular biology, innate immunity and microbiology.  Bill describes himself as “incredibly lucky” to be working with Lena everyday, because despite the complexities it can sometimes create, they “get the chance to interact on such a multi-dimensional way.”  It is, however, the interdisciplinary nature of the Gerwick lab as a whole that makes them a unique group of scientists.  Dr. Bill Gerwick sees the lab’s interdisciplinary qualities as valuable because “it is at the confluence of a variety of disciplines where one finds a rich interface that is ripe with opportunity and innovation.  We consciously try to create that interface in the context of a lab through the basic application of biology, analytical and organic chemistry, pharmaceutical sciences, molecular biology and biosynthesis.” By bringing together an expertise in these varied disciplines the lab has been able to explore the unique chemical adaptation of marine algae and cyanobacteria and how those adaptations might be useful in a variety of biomedical or biotechnological applications.

To explore the unique chemical adaptations of marine life one needs to travel to unique habitats.   Dr. Bill Gerwick and his students make regular collection trips to distant locations to find novel strains of algae and cyanobacteria.  “Each collection trip takes us to new parts of the world at different times of the year and we find different organisms.  Those organisms are the engine that drives the downstream chemistry and biology pursuits of our lab.” The lab has accumulated samples from 16 different countries including remote places like Papua New Guinea, Panama, Madagascar and even Palmyra Atoll in the middle of the Pacific.  From these trips Gerwick and his students bring back live samples as well as larger collections preserved for chemical investigations and DNA isolation.  It is from this treasure trove of samples that the lab has amassed a collection of over 100 live cyanobacterial strains in culture, over 18,000 extracts and purified fractions and 129 pure compounds.  Maintaining a culture collection of so many strains is no small task and Tara Byrum (a multi-talented biologist/lab manager) is the one who keeps it all running.  “It’s exciting to see all of the samples coming into the lab from collection trips and having seen what happens with the samples afterwards I really like how we use chemistry and molecular biology for such a multi-disciplinary approach “

Dr. Bill Gerwick and the author, graduate student Cameron Coates, on a collection trip in Papua New Guinea

            The isolation and identification of natural products from marine algae and cyanobacteria has been a major focus of the lab over the last 25 years.  This effort has yielded compounds like Curacin A, an anti-cancer drug candidate that is active against colon, kidney and breast cancer cell lines.   The compound was isolated from a filamentous marine cyanobacterium from Curacao in the late 90’s and the unique structural characteristics and activity it possesses has driven the lab to investigate the biosynthesis of this molecule and learn more about its activity against cancer cells.  Moorea producta, the cyanobacterium that produces Curacin A, also produces a variety of other novel secondary metabolites.  The lab recently sequenced the genome of this cyanobacterium to investigate the pathways involved in producing Curacin A and these other secondary metabolites.  The results of this sequencing project were recently published in PNAS and can be found here.

Lab Technician Tara Byrum

            The lab plans to maintain their effort in drug discovery while joining forces with SD-CAB and applying their expertise in organic chemistry and molecular biology to biofuel applications.  Growing interest in developing algae as a source of biofuels has opened up many opportunities for the lab to explore new projects that connect their work in natural products to biofuels.  For example, the biomass that remains after the algae has been extracted for fuels may contain compounds that could be used for other biotechnology applications like a pharmaceutical.  These compounds are commonly referred to as “co-products” and members of the Gerwick lab are actively working on identifying potential co-products.   Separately, the lab is working more directly on biofuel applications using cyanobacteria and diatoms.  Emily Trentacoste, a 3^rd year PhD student in the lab is investigating lipid pathways in diatoms with hopes to identify ways to increase yields of triglycerides that could be converted to biodiesel.   

Cameron Coates, a 4^th year PhD student in the lab is investigating hydrocarbon biosynthesis in cyanobacteria.  Cyanobacteria naturally produce hydrocarbons that could be used as a jet fuel directly at about 1-2% of their dry biomass and it appears that they are making these hydrocarbons from fatty acids.  He is investigating the unique enzymes that cyanobacteria use to produce these hydrocarbons and hopes to engineer these enzymes into microbes that would eventually produce a large yield of high quality fuel that could avoid the costly and energy intensive steps of converting fatty acids and triglycerides into diesel or gasoline.  Interestingly, one of these hydrocarbon producing enzymes was discovered as a direct result of the investigations into the biosynthetic pathway for Curacin A, thus creating a direct connection between the labs work on natural products and biofuels.  It is just this type of finding that reinforces the interdisciplinary approach of the Gerwick Lab and will continue to fuel their future research for years to come.

Marine cyanobacterium Moorea producta

 

Cameron Coates is Ph.D. candidate at UCSD and a volunteer writer for SD-CAB. You can contact him at rccoates@ucsd.edu.