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Consolidated bioprocessing, or CBP, the conversion of lignocellulose into desired products in one step without added enzymes, has been a subject of increased research effort in recent years. In this review, the economic motivation for CBP is addressed, advances and remaining obstacles for CBP organism development are reviewed, and we comment briefly on(More)
BACKGROUND Temperature-sensitive (Ts) plasmids are useful tools for genetic engineering, but there are currently none compatible with the gram positive, thermophilic, obligate anaerobe, Clostridium thermocellum. Traditional mutagenesis techniques yield Ts mutants at a low frequency, and therefore requires the development of high-throughput screening(More)
UNLABELLED BACKGROUND Industrial production of biofuels and other products by cellulolytic microorganisms is of interest but hindered by the nascent state of genetic tools. Although a genetic system for Clostridium thermocellum DSM1313 has recently been developed, available methods achieve relatively low efficiency and similar plasmids can transform C.(More)
In Clostridium thermocellum, a thermophilic anaerobic bacterium able to rapidly ferment cellulose to ethanol, pyruvate kinase (EC 2.7.1.40) is absent based on both the genome sequence and enzymatic assays. Instead, a new pathway converting phosphoenolpyruvate to pyruvate via a three-step pathway involving phosphoenolpyruvate carboxykinase, NADH-linked(More)
BACKGROUND The native ability of Clostridium thermocellum to rapidly consume cellulose and produce ethanol makes it a leading candidate for a consolidated bioprocessing (CBP) biofuel production strategy. C. thermocellum also synthesizes lactate, formate, acetate, H2, and amino acids that compete with ethanol production for carbon and electrons. Elimination(More)
BACKGROUND Clostridium thermocellum is a model thermophilic organism for the production of biofuels from lignocellulosic substrates. The majority of publications studying the physiology of this organism use substrate concentrations of ≤10 g/L. However, industrially relevant concentrations of substrate start at 100 g/L carbohydrate, which corresponds to(More)
BACKGROUND Cellulose is highly recalcitrant and thus requires a specialized suite of enzymes to solubilize it into fermentable sugars. In C. thermocellum, these extracellular enzymes are present as a highly active multi-component system known as the cellulosome. This study explores the expression of a critical C. thermocellum cellulosomal component in T.(More)
BACKGROUND Thermoanaerobacter saccharolyticum is a thermophilic microorganism that has been engineered to produce ethanol at high titer (30-70 g/L) and greater than 90 % theoretical yield. However, few genes involved in pyruvate to ethanol production pathway have been unambiguously identified. In T. saccharolyticum, the products of six putative pfor gene(More)
UNLABELLED NfnAB catalyzes the reversible transfer of electrons from reduced ferredoxin and NADH to 2 NADP(+). The NfnAB complex has been hypothesized to be the main enzyme for ferredoxin oxidization in strains of Thermoanaerobacterium saccharolyticum engineered for increased ethanol production. NfnAB complex activity was detectable in crude cell extracts(More)
Clostridium thermocellum is a thermophilic anaerobic bacterium which efficiently hydrolyzes and metabolizes cellulose to ethanol through the action of its cellulosome, a multiprotein enzymatic complex. A fluorescent protein probe, consisting of a type II dockerin module fused to a SNAP-tag, was developed in order to gain insight into the quaternary(More)