Monday, May 4, 2009
11-07
Biohydrogen production converted from lignocellulose: a novel source and approach from wood-feeding termites
Jianzhong Sun1, Yueqing Cao1, and Jose Rodriguez2. (1) Coastal Research and Extension Center, Mississippi State University, 810 Hwy. 26 West, P.O. Box 193, Poplarville, MS 39470, (2) Mississippi State Chemical Laboratory, Petroleum Prod. Div.,, Mississippi state University, Starkville, MS 39762
In nature, wood-feeding termites possess a great capability to digest lignocellulose and with the unique mechanisms to emit a significant amount of H2 from their guts into atmosphere. The efficacy of H2 emission by wood-feeding termites could vary from 122–12348 nmol h-1g of termite body weight-1, depending on termite species, food source, and food modification that would affect methanogenesis and other bacteria who uptake H2 for synthesizing CH4 or other products. Our recent investigations for three wood-feeding termites, Reticulitermes flavipes, R. virginicus, and Coptotermes formosanus indicated that H2 emission during 3 h incubation was significant and continuous at the rates of 3076.01 ± 229.47, 12348.84 ± 1130.53, and 1241.48 ± 131.95 nmol h-1g of termite body weight-1, respectively. The antibiotic treatments at a proper concentration on termite diets would significantly enhance H2 production at least 5 times of H2 production recorded on non-treated diet by C. formosanus, which suggested that H2 production is mainly attributed to the dense population of symbiotic cellulolytic protozoa in termite hindguts. These investigations also represent a novel source of biohydrogen from termites and the unique mechanisms producing hydrogen from cellulosic substrates that showed the highest H2 conversion rate from lignocellulose among present technologies in biological hydrogen processes (e. g. 12.6655 ± 1.1595 mmol gaseous H2 (~0.28 liter H2) when consuming one gram of pine wood by R. virginicus). The production of biohydrogen and mechanisms via wood-feeding termites demonstrates a distinct departure from other biological hydrogen routes with low conversion rates.