The Waterborne Symposium

Coatings make a significant contribution toward combating the problem of increased atmospheric carbon dioxide (CO2) levels and detrimental impacts of climate change. Ocean-bound algae exist primarily as a thin layer that spreads over vast oceans surfaces currently accounting for most (70 - 80%) of the earth’s photosynthetic conversion of CO2 into oxygen (O2).  This thin layer of horizontal algae has been mimicked in land-based platforms, while minimizing the footprint of land needed by converting the system into coated vertical arrays.  Natural polymer gels have long been used to support the growth of living cells.  Translucent coatings have been designed and prototyped that retain high levels of moisture (> 80% water content) when applied over large vertical surfaces and produce usable products within the coating that can be recovered for added market value. To achieve this, an alga engineered to express genes from a bacterial cellulose producer was used.  As these algae are photosynthetic, this strain produces cellulose from captured CO2 and sunlight. We demonstrate that these genetically-modified algal cells are not only viable in the coating system for months, but they also actively capture CO2 and produce cellulose.  Furthermore, the current coating can be removed from the vertical substrate and easily disassociated, releasing the cellulose for collection.  Other algae have the potential to be genetically modified in a similar manner, whether to produce usable products such as cellulose and other polysaccharides (or protein/fatty acids) or to tailor the host alga for the application conditions, such as arid and/or high light conditions.  This research opens a new field by merging genetically engineered microbes with coatings to produce usable and harvestable products while also sequestering CO2 in the process.