Tuesday, April 30, 2013
Exhibit Hall
Lignocellulosic biomass is one of the most plentiful renewable natural resources that can be used for the production of fuels and chemicals. Lignocellulosic biomass is mainly composed of cellulose, hemicellulose and lignin. General constituents of cellulose, hemicellulose, and lignin are glucose, xylose and aromatic heteropolymer (phenyl propanoid), respectively. The lignin which is the most abundant natural aromatic polymer is known to be recalcitrant for biodegradation. In this study, we report two bacterial strains isolated from forest soil, which have potential abilities to degrade cellulose, xylan and lignin. These strains, designated CGM123 and GWD275 are aerobic and mesophilic. These two strains showed the distinct clear zone around the microbial colonies on carboxymethyl cellulose and beechwood xylan agar plates using Congo red staining method. Additionally, we analyzed cellulase and xylanase activities by measuring reducing sugars using 3,5-Dinitrosalicylic acid (DNS) method. Interestingly, strains CGM123 and GWD275 indicated extracellular peroxidase activity which could be related to lignin degradation. The extracellular peroxidase activity was assayed by enzymatic oxidation of 2,4-dichlorophenol (2,4-DCP) in the presence of hydrogen peroxide and 4-aminoantypirene. Based on the results, two soil isolates are likely to have potential capabilities degrading cellulose, xylan and lignin simultaneously. The 16S rRNA gene sequences of these strains were used as a query against the EzTaxon database. The phylogenetic analysis showed that strain CGM123 is classified as a new genus of phylum Bacteroidetes. Strains CGM123 and GWD275 showed highest similarities with Filimonas lacunae (93.03%) and Bacillus methylotrophicus (99.86%), respectively.