Hydrolysis of lignocellulosic feedstock by novel cellulases originating from Pseudomonas sp. CL3 for fermentative hydrogen production

Abstract

A newly isolated indigenous bacterium Pseudomonas sp. CL3 was able to produce novel cellulases consisting of endo-β-1,4- d-glucanase (80 and 100 kDa), exo-β-1,4- d-glucanase (55 kDa) and β-1,4- d-glucosidase (65 kDa) characterized by enzyme assay and zymography analysis. In addition, the CL3 strain also produced xylanase with a molecular weight of 20 kDa. The optimal temperature for enzyme activity was 50, 45, 45 and 55 °C for endo-β-1,4- d-glucanase, exo-β-1,4- d-glucanase, β-1,4- d-glucosidase and xylanase, respectively. All the enzymes displayed optimal activity at pH 6.0. The cellulases/xylanase could hydrolyze cellulosic materials very effectively and were thus used to hydrolyze natural agricultural waste (i.e., bagasse) for clean energy (H 2) production by Clostridium pasteurianum CH4 using separate hydrolysis and fermentation process. The maximum hydrogen production rate and cumulative hydrogen production were 35 ml/L/h and 1420 ml/L, respectively, with a hydrogen yield of around 0.96 mol H 2/mol glucose.