Improvement of Cellulolytic Properties of Clostridium cellulolyticum by Metabolic Engineering

Abstract

Cellulolytic clostridia have evolved to catabolize lignocellulosic materials at a seasonal biorhythm, so their biotechnological exploitation requires genetic improvements. As high carbon flux leads to pyruvate accumulation, which is responsible for the cessation of growth of Clostridium cellulolyticum, this accumulation is decreased by heterologous expression of pyruvate decarboxylase and alcohol dehydrogenase from Zymomonas mobilis. In comparison with that of the wild strain, growth of the recombinant strain at the same specific rate but for 145 h instead of 80 h led to a 150% increase in cellulose consumption and a 180% increase in cell dry weight. The fermentation pattern was shifted significantly: lactate production decreased by 48%, whereas the concentrations of acetate and ethanol increased by 93 and 53%, respectively. This study demonstrates that the fermentation of cellulose, the most abundant and renewable polymer on earth, can be greatly improved by using genetically engineered C. cellulolyticum.

ISCce 1 and ISCce 2 , Two Novel Insertion Sequences in Clostridium cellulolyticum

“…Functional studies of the cellulosomes have been restricted so far to biochemical studies of recombinant subunits overproduced in E. coli (4,16,19,38). Gene transfer techniques were recently developed for C. cellulolyticum (25,44) and were used to modify its fermentation pathways (22). However, no description of a mutagenic system allowing random or targeted mutagenesis has been described so far for this bacterium.…”

Lignocellulosic Biomass Utilization Toward Biorefinery Using Meshophilic Clostridial Species

“…Butamax TM is collaborating with Kingston Research Limited, another BP-Dupont joint venture, to build a demonstration plant in the UK. Previously, the cellulosome-producing C. cellulolyticum has also been genetically engineered for improved ethanol production [36]. With this respect, most of the research concerning the construction of an organism for consolidated bioprocessing has focused on ethanol production.…”

Advances in consolidated bioprocessing systems for bioethanol and butanol production from biomass: a comprehensive review

“…Guedon et al (2002) could decrease accumulation of pyruvate, which is responsible for the cessation of growth, by heterologous expression of pyruvate decarboxylase and alcohol dehydrogenase from Z. mobilis in C. cellulolyticum. The recombinant strain showed a 150% increase in cellulose consumption and a 180% increase in cell dry weight after 145 h in comparison with the wild type strain.…”