TERMITE BIOMASS ENERGY conversion offers a potential 95% to 99% efficiency in converting woody plants into usable energy forms comparable to ethanol fuels and petroleum products. “Termites are regarded as harmful because of the ability to decompose cellulosic materials such as houses made of wood,” said University of the Ryukyus (Okinawa, Japan) researchers Toru Matsui, Gaku Tokuda and Naoya Shinzato in the journal Recent Patents on Biotechnology. However, “Termites and/or their symbionts (e.g. gut protozoa & bacteria) are potentially good resource of functional genes for industrial applications…for biomass utilization, environmental remediation, and fine-chemicals production.”
Several termite genes have already been patented for biofuel (cellulase) and fighting infections (antimicrobial peptides). Combinations of cellulase enzymes and anaerobic symbionts have also been harnessed to produce hydrogen fuel (H2 gas) from waste plastics. “Lignin treatment by anaerobic bacteria from the gut of” several termite species has also been patented; thus pointing towards a greener pathway in place of today’s less environmentally-friendly caustic chemical processes. Termite energy production mechanisms might also be released as Open Source scientific information, instead of patented, as was once common in the scientific world. Indeed, the real practical innovations for sustainable world energy production may be in turning the raw material of biological science basic research into economical applied chemical engineering and bio-engineering solutions. In other words, a new energy production landscape dotted with bio-refineries approaching the 95% to 99% energy conversion efficiency of termite guts digesting woody plant and fiber materials is an objective worth working towards.
Being an ancient insect order, termites have been tapping into Earth’s abundant woody plant resources for perhaps 400 million years; well before dinosaurs and then humans roamed and pillaged the planet. “Cellulose is the most abundant biomass on the earth,” write the Ryukyus researchers. “Termites thrive on plant biomass, in which the major constituents are cellulose, hemicellulose (i.e. non-cellulosic carbohydrates), and lignin…In addition, it can be hydrolyzed to give a sugar pool which can be subsequently fermented to form ethanol, etc. However, the crystalline nature of cellulose had made it difficult to economically convert into useful chemical feedstocks…Other than cellulosic materials decomposition, there could be symbionts degrading lignin-derived compounds, a significant part of the wood constituents.”
At the hops-soaked Entomological Society of America (ESA) annual meeting in Portland, Oregon, the parallels between microbrewing (hops & microbes), baking (yeasts; Voodoo donuts) and termite guts as fermentation vats (bio-refineries) producing energy fuels was bubbling just below the surface. Several research labs, including Michael Scharf’s Purdue University lab, are evaluating the genes and metabolic processes innate to termites as well as the contributions of protozoa, bacteria and other microbes living as symbionts in termite guts and helping digest plant lignins and cellulose into usable energy compounds. Figuring out how termites and their gut microbes are such efficient converters of plant matter into energy is a huge undertaking, even with the latest DNA and genetic tools.
Brittany Peterson, an ESA termite biofuel presenter working in Scharf’s lab writes on her web page about “the co-evolution of termites and their over 4,000 symbiotic microorganisms.” The implication being that the termite hindgut is a bio-refinery where termites and their microbial symbionts constitute the equivalent of a vast unknown ecosystem whose parameters are just now being delimited. Peterson and the Scharf lab view termite guts as a model system for studying synergy and biomass processing of tough toxins like lignin. In other words, as the basis and inspiration for designing green bio-refineries for alternative energy and feedstock production processes more energy efficient than turning food crops like corn into ethanol fuel.
Of course, this means figuring out exactly how termites and their several thousand hindgut microbes extract simple sugars from wood’s complex lignin-cellulose polymer structure. This termite/microbe “digestion” (or depolymerization) has an amazing 95%-99% efficiency that industrial biomass processing or biofuel production cannot match even using very toxic caustic chemistries. Most research on termite gut microbes has focused on protozoa, but Peterson envisions adding bacteria and termite-produced enzymes to create a synergistic bio-refinery mixture. In other words, replacing current caustic and energy inefficient biomass conversion chemistries with greener, more energy efficient biological technologies composed of termite-derived enzymes, bacteria and protozoa to depolymerize biomass and produce usable sugars/energy.
The synergy of termite (host) and gut microbes likely makes possible the observed over 95% lignin-cellulose biomass processing efficiency; 82% of the genes for lignin-cellulose processing, including high expression of cellulase enzymes, come from or are innate to the termite itself rather than the symbiotic gut microbes, Peterson told the ESA annual meeting. Though the termite-microbe synergism boosts the the energy efficiency to quite high levels approaching 100%. At least for woody materials.
Interestingly, though, when termites eat paper, most of the biomass processing genes come from the gut microbes. Thus, a quite complex digestive ecosystem that seems to vary greatly with the food (feedstock) input. The gut microbes also help termites detoxify harmful materials and provide antioxidant protection. Scientific bioassays using various combinations of antibiotic drug treatments and anti-protozoa diets are enabling the Scharf lab to construct a microbial “library” for continuing research, Peterson told the ESA. Recent experiments with bacteria isolated from the subterranean termite Reticulitermes flavipes, indicate that the bacteria either alone or via interaction with protozoa boost glucose (sugar; an energy feedstock) release from lignin-cellulose (plant) biomass.
In the future, it is conceivable that bio-refineries using termite enzymes, bacterial enzymes and protozoa will make today’s ethanol and biomass to energy conversion processes look like toxic, inefficient relics of a primitive industrial energy production past. But it will likely be many more years before bio-engineers and chemical engineers are ready to begin the commercial harvest of termite energy to power our vehicles, the Internet, etc.