Getting biofuel supplies from seaweed has taken a giant leap forward from work by Yong-Su Jin, a University of Illinois Assistant Professor of Microbial Genomics and a faculty member in the university’s Institute for Genomic Biology.
Jin and his large international team have developed a strain of yeast that can make short work of fermenting galactose using red seaweed for the feedstock.
Jin points out galactose is one of the most abundant sugars in marine biomass so its enhanced fermentation will be industrially very useful for seaweed biofuel producers.
Marine biomass is a high potential renewable source for the production of biofuels for three reasons. Of prime importance, production yields of marine plant biomass per unit of sunlit area are much higher than those of terrestrial biomass – dwarfing even miscanthus and sugarcane. For processing, marine biomass can be depolymerized relatively easily compared to other biomass crops because it either contains less or does not contain the difficult lignin and cellulose crystalline structures, vastly cutting into the capital investment and operating complexity and costs. As already seen in micro algae the rate of carbon dioxide fixation and conversion to carbohydrates by aquatic biomass is much higher than by terrestrial biomass, making it an appealing option for sequestration and recycling of carbon dioxide, opening more fossil fuel effluent to recycling.
The expected large land plant based increases of biofuels made from terrestrial biomass crops are delayed by waiting for technology improvements for breaking down lignin and cellulose fibers and extracting the fermentable sugars. The existing harsh pretreatment processes used to release the sugars result in toxic byproducts, inhibiting subsequent microbial fermentation and creating a complex and expensive waste issue.
Marine biomass can be much more easily degraded to fermentable sugars, and production rates and range of plant species distribution are higher than terrestrial biomass. The entire seacoast of the planet, any viable brackish water that can be exposed to sun and contained, plus environments from Arctic to Antarctic offer production potential.
The Illinois team’s breakthrough comes from galactose fermentation, a major product of marine biomass. Until Jin’s work found an answer, galactose fermentation has been very inefficient.
In a classical understatement Jin said, “This discovery greatly improves the economic viability of marine biofuels.”
Jin and his colleagues identified three genes in Saccharomyces cerevisiae, the microbe most often used to ferment the sugars, whose overexpression increased galactose fermentation by 250 percent when compared to a control strain. Overexpression of one gene in particular, a truncated form of the TUP1 gene, sent galactose fermentation numbers soaring.
Plus the team’s new strain consumed both sugars (glucose and galactose) almost three times faster than the control strain — 8 versus 24 hours. Jin said, “When we targeted this protein, the metabolic enzymes in galactose became very active. We can see that this gene is part of a regulating or controlling system.”
The team’s paper, Improved Galactose Fermentation of Saccharomyces Cerevisiae Through Inverse Metabolic Engineering is available online at the journal Biotechnology and Bioengineering.
Red seaweed is a name for a set of species numbering in the thousands. Also there are green and brown species groups. Species of all three are used in numerous ways today. Thus like the corn ethanol model, seaweed has a visible route to biofuel production. But, which seaweeds and what cultivation and processes to fuels path will be dominant over time is a huge set of experiments and trials away.
The overwhelming fact that seaweed and other possible ocean and marine plants have a huge productivity advantage over today’s land plants of corn and sugarcane is now getting important answers for the processing to fuel side. There is already an experience base for seaweed cultivation, equipment designs for harvesting and handling the material, transport can be simply a flowing pipe, and other advantages. The marine based ethanol or other alcohol-based production over a few years could and likely will re-map the alternative fuels business.
With that in mind seaweed processing remnants are mineral rich, by as much as 20 times or more and contain far more elements than corn or sugarcane. Uses could be returning trace elements to the growing medium, concentrating and separating the materials for sale and other ideas for making a secondary market for the refuse part of fuel production. It could become a rich treasure trove, the minerals range from light metals to heavy actinides like uranium. Then there are the organic remains as well including protein. Seawater and brackish water sources could become concentrated mineral deposits, food resources+ and freshened water supplies. We’ll soon see surveys of brackish water for aquaculture site determination underway.
The investment battle has been joined – its land based agriculture of sugarcane and corn vs. aquaculture of macro algae and other organisms. As we’re seeing now, the yield per area, the processing costs and the refuse value comparison is all – advantage to aquaculture – in a large way.
There aren’t all that many or difficult aquaculture technical issues to work out. Vast areas that are near to brackish water and near oceans can be reformed for aquaculture. Be sure that next vehicle is FlexFuel capable.
The international team members include Suk-Jin Ha of the U of I’s Institute of Genomic Biology; Ki-Sung Lee, Min-Eui Hong, Suk-Chae Jung, and Dae-Hyuk Kweon of Sungkyunkwan University; Byoung Jo Yu, Hyun Min Koo, Sung-Min Park, and Jae Chan Park of the Samsung Advanced Institute of Technology; and Jin-Ho Seo of Seoul National University. Funding was provided by the Samsung Advanced Institute of Technology; the BioGreen 21 Program, Rural Development Administration, Republic of Korea; and the Korea Research Foundation.
By. Brian Westenhaus of New Energy and Fuel