The Council for Scientific and Industrial Research (CSIR) researchers are isolating genes that encode enzymes that are capable of breaking down cellulose from the gut of sugarcane-feeding termites. The team is using modern metagenomics tools to access these genes. To date, the team has isolated in excess of 30 functional genes related to plant biomass degradation. Ultimately, the challenge for the researchers is to mimic the way termites break down hardy plant biomass, with the aim of developing a robust technology for converting agricultural biomass to clean burning fuel, using enzymes derived from the microorganisms in the guts of termites.
These pests are very efficient in converting a wide variety of plant biomass as part of their metabolic mechanism for generating carbon and energy for growth and survival. The termites rely on bacteria and protozoa that inhabit their digestive tracts to do this. These mutualistic microbes naturally generate a broad range of enzymes that convert the cellulosic materials into fermentable sugars.
The Lignocellulosic enzyme additive feedstock (LEAF) project is funded by the Technology Innovation Agency (TIA) and work is undertaken in collaboration with the University of the Western Cape and Stellenbosch University. Novel enzyme genes from the termites linked with their digestive abilities could have significant bioprospecting potential in the green energy sector.
Dr Konanani Rashamuse, a senior researcher at the CSIR, says: “We are working hard in formulating a best enzyme combination that will yield maximal release of simple sugars. The competition in this area is very intense worldwide. Although there is still a need for more research and development, there is hope that enzymes from termites may just be what the energy sector needs.
“The number of genes we have isolated to date provide the basis for technology development for our targeted substrate, which is a sugarcane bagasse (a waste by-product from sugarcane processing),” says Rashamuse.
In agriculture, and particularly in crop farming, termites are notorious pests, infamously known for costing the sector millions of rands annually in crop damage. Termites are herbivores, feeding on plant-based diets (including grass, leaves and decaying plant matter). In short, plant materials are a ‘juicy meat’ from the termites’ perspective. It is this reliance on a plant biomass diet that is providing researchers with the opportunity for developing new alternative energy sources.
“These plant-feeding pests are, from the biotechnology point of view, a wonderful model for biofuel production. While crop farmers may look at them and run for pesticide sprays, a scientist like myself looks at them with excitement and see a natural reactor that could potentially provide us with future answers to the development of alternative energy sources,” Rashamuse elaborates.
“Plant cell walls are made of at least three major compounds: lignin, hemicelluloses and cellulose, which are held together by strong chemical bonds. The combination of these compounds is what gives the plants structure, rigidity and more importantly, a protective barrier against pathogen invasion and attack. These compounds are very rich in energy, which has been derived from the sun through photosynthesis. Using enzymes, which are the ubiquitous proteins that accelerate chemical reactions, compounds such as hemicelluloses and cellulose can be broken down into simple sugars that can be fermented to produce fuel alcohol.
“Termites’ guts contain a wide variety of bacteria that release a battery of enzymes to break down plant material, including cellulose, to simple sugars. It is a pity for us that termites don’t spew these enzymes for biofuel production, but rather use these digestive processes internally to access carbon for growth and survival,” says Rashamuse.
“Enzymes are produced in cells according to specific genetic codes on the cellular DNA. Access to these genes within microorganisms residing within the gut of termites is where an opportunity for biofuel production lies. The thrust of this technology development project is on getting our hands on these tailor-made biocatalysts,” adds Rashamuse. (Source:CSIR, visit them at http://www.csir.co.za )