1-05: Metabolic engineering of a pyruvate metabolic pathway in the hyperthermophilic bacterium, Cadicellulosirutor bescii CBJW018

Thermophilic organisms offer special advantages for the conversion of lignocellulosic biomass to biofuels and bioproducts. The use of these complex substrates often requires chemical and thermal pretreatment and the addition of hydrolytic enzymes that partially digest the plant cell walls. Enymatic pretreatment is expensive and often prohibitive for the production of low value commodity products. Members of the Gram-positive bacterial genus Caldicellulosiruptor are anaerobic thermophiles with optimum growth temperatures between 65 °C to 78 °C and are the most thermophilic cellulolytic organisms known. C. bescii is capable of using both unpretreated switchgrass and populous for growth. We recently developed methods for genetic manipulation of members of this genus and here we report the first mutants for metabolic engineering of these bacteria for production of biofuels and bioproducts from biomass. Deletions of lactate dehydrodenase and acetate kinase (as well as phosphate transacetylase) affected ethanol production and ethanol tolerance without affecting growth. Additional mutations that allow for direct microbial conversion of biomass to products of interest will be reported.