(582q) Potential of Thermophilic Bioprocessing of Lignocellulosic Biomass for Generation of Biofuels

Kainth, A. S., South Dakota School of Mines and Technology
Bhalla, A., South Dakota School of Mines & Technology
Bibra, M., SDSMT
Kumar, S., South Dakota School of Mines & Technology
Sani, R. K., South Dakota School of Mines & Technology

Thermophiles and their enzymes will likely play important roles in many kinds of bioprocessing (e.g., in conversion of non-food biomass into biofuels including bioethanol, biodiesel, biobutanol, and biogas, bioremediation of contaminated aquifers, and production of pharmaceuticals). Thermophilic bioprocessing of lignocellulosic biomass to biofuels, through the use of elevated temperatures, offers several advantages including improved hydrolysis of cellulosic substrates, higher mass-transfer rates leading to better substrate solubility, lowered risk of contamination, and increased flexibility with respect to process design thus improving the overall economics of the process.  Using soil/biofilm samples of deep biosphere (1.34 km) of the Homestake Gold Mine, Lead, SD, compost facility, and Hot Springs State Park in Thermopolis WY, we have isolated several thermophilic cellulose- and xylan-degrading pure cultures belonging to the genera Brevibacillus, Paenibacillus, Bacillus, and Geobacillus.  Unique characteristics of cellulases and xylanases produced by mine and compost thermophiles include optimum temperatures of >70°C, pH ranges from 4 - 8, and high thermostability (e.g., at 60ºC, 50% of cellulases and xylanases activities were retained in 35 and 23 days of incubation, respectively).  Currently, we are working on heterologous expression of thermo-stable enzymes, without reducing enzymatic activity and thermo-stability, in suitable hosts so as to have higher production of these industrially important enzymes. Along with this, we are trying to elucidate the structure-function relationship of these thermostable enzymes and the structural factors that leads to their thermo-stability.  The significant and immediate impact of ongoing research will be not only on biofuel research, but also on the national economy through the development of an efficient, economical, and sustainable biofuel production process.