• Energy Research

Abstract Corncob dust is a byproduct from animal feed industry. Based on the major components, it has potential as an alternative carbon source for bio-ethanol production. To determine maximum glucose from corncob dust, incremental variables were tested: first, corncob to acid ratio (1:5 - 1:15 w/v), then, sulfuric acid concentrations (0.5%, 2%, 5% v/v), next, temperatures (80-120°C) and reaction time (0-5 h). The maximum glucose of 2.80 g/l with 0.24 g/l xylose were obtained from the optimum hydrolysis conditions at 1:10 corncob to acid ratio using 2% sulfuric acid under 110°C for 5 h. The activation energy for glucose and xylose production from corncob dust hydrolysis estimated using Arrhenius equation were 108.1 and 40.7 kJ/mole, respectively. Ethanol yield from fermentation of corncob dust hydrolysate by Candida shehatae was 1.39 mole-ethanol/mole-glucose, which was equivalent to 1,807 kJ/mole-substrate. Energy produced from ethanol was 16.8 times higher than that from energy consumed in the hydrolysis process. Therefore, bio-energy production from corncob dust hydrolysate was very efficient.

Abstract Hot spring water and soil samples collected from various locations in Thailand were screened as thermophilic lignocellulase producers. Isolate J12, which showed the highest carboxymethylcellulase (CMCase) activity was selected for further enzymatic characterization. The isolate J12 exhibited both CMCase and xylanase acitvities. Optimum temperature for the J12 CMCase and xylanase acitvities were found to be the same at 60°C. But optimum pH were slightly different at pH 6.0 and 5.5, respectively. Both enzymes were stable at high temperatures and retained more than 60 % of their activities after 20 min at 60°C. Therefore, CMCase and xylanase produced from the selected bacterium showed thermophilic properties as to stability as well as activity. Plant degradation potential of J12 enzymes was also investigated using corncob and Napier grass. The result revealed that hydrolytic efficacy of this enzyme on corncob 13.2 % was superior to Napier grass at 9.6 %. Morphology and 16S rDNA sequencing results indicated that the bacterial isolate J12 was Bacillus sp.