Free and Cellulose-bound Cellulases in a Cellulomonas Species

A cellular automaton model of crystalline cellulose hydrolysis by cellulases

BACKGROUND Cellulose from plant biomass is an abundant, renewable material which could be a major feedstock for low emissions transport fuels such as cellulosic ethanol. Cellulase enzymes that break down cellulose into fermentable sugars are composed of different types - cellobiohydrolases I and II, endoglucanase and β-glucosidase - with separate functions. They form a complex interacting netwo...

Precise excision of the cellulose binding domains from two Cellulomonas fimi cellulases by a homologous protease and the effect on catalysis.

An endo-beta-1,4-glucanase (CenA) and an exo-beta-1,4-glucanase (Cex) were prepared from Escherichia coli expressing recombinant DNA of the cellulolytic bacterium Cellulomonas fimi. Purification was facilitated by the high affinities of these enzymes for cellulose. An extracellular C. fimi protease cleaved both enzymes in vivo in a highly specific manner. The affinity of the parent enzyme for c...

Cellulose hydrolysis with thermo- and alkali-tolerant cellulases in cellulose- dissolving superbase ionic liquids

Selecting β-glucosidases to support cellulases in cellulose saccharification

BACKGROUND Enzyme end-product inhibition is a major challenge in the hydrolysis of lignocellulose at a high dry matter consistency. β-glucosidases (BGs) hydrolyze cellobiose into two molecules of glucose, thereby relieving the product inhibition of cellobiohydrolases (CBHs). However, BG inhibition by glucose will eventually lead to the accumulation of cellobiose and the inhibition of CBHs. Ther...

Cellulose Decomposition and Associated Nitrogen Fixation by Mixed Cultures of Cellulomonas gelida and Azospirillum Species or Bacillus macerans.

Mixed cultures of Cellulomonas gelida plus Azospirillum lipoferum or Azospirillum brasilense and C. gelida plus Bacillus macerans were shown to degrade cellulose and straw and to utilize the energy-yielding products to fix atmospheric nitrogen. This cooperative process was followed over 30 days in sand-based cultures in which the breakdown of 20% of the cellulose and 28 to 30% of the straw resu...