Molecular Mechanisms of Marine Polysaccharide Depolymerization and Metabolism

点击翻译按钮获取中文摘要

Ocean plant biomass [i.e. microalgae and macroalgae (seaweed)] is estimated to be only ~1/200 that of terrestrial plant biomass. Indeed, most of the carbon incorporated by photosynthetic processes is in land plants. However, the annual turnover rate (total mass per time) of photosynthetically fixed carbon in the oceans is roughly equal to that on land, indicating a highly dynamic process with a normalized rate of recycling that is hundreds of times greater than on land. In both the marine and land environments this carbon is locked primarily in the form of sugar chains called polysaccharides. The microbial degradation of terrestrial plant polysaccharides, cellulose being the major example, has been intensely studied for over 50 years and it is therefore relatively well understood; the same is not true of marine algal polysaccharides. The polysaccharides present in seaweed comprise a group of complex sugars that are chemically different from those of terrestrial plants. The vision that drives this research program, therefore, is to identify and define the largely unexamined molecular features of the unique metabolic systems that enable bacteria to metabolize marine polysaccharides. Determining how photosynthetically fixed carbon is recycled in our oceans is fundamental to the basic goal of understanding the global carbon cycle. However, in our world of climate change, the promises of renewable resources, carbon neutral footprints, and alternative fuel sources are increasingly attractive. Marine algae are an extremely appealing renewable resource with a high carbohydrate content. The proposed research program is generating a knowledge platform that can be leveraged to design strategies for the conversion of this biomass into fermentable sugars, which could then be converted into biofuels or other useful bioproducts. Additionally, many marine polysaccharides are used in foods, cosmetics, agriculture, and potential medical therapeutics. This research is providing a new set of tools to enzymatically modify these polymers to potentially control their properties in these applications. Finally, this work is also providing novel insights into the metabolic capabilities of the bacteria that inhabit human and animal guts where they aid digestion of dietary marine polysaccharides. This innovative research program, which is the only one of its kind in Canada, has the potential to transform a field that has a remarkably wide impact.