Abstract: Mutant thermophilic organisms that consume a variety of biomass derived substrates are disclosed herein. Strains of Thermoanaerobacterium saccharolyticum with acetate kinase and phosphotransacetylase expression eliminated are disclosed herein. Further, strain ALK1 has been engineered by site directed homologous recombination to knockout both acetic acid and lactic acid production. Continuous culture involving a substrate concentration challenge lead to evolution of ALK1, and formation of a more robust strain designated ALK2. The organisms may be utilized for example in thermophilic SSF and SSCF reactions performed at temperatures that are optimal for cellulase activity to produce near theoretical ethanol yields without expressing pyruvate decarboxylase.

Abstract: One aspect of the invention relates to a genetically modified thermophilic or mesophilic microorganism, wherein a first native gene is partially, substantially, or completely deleted, silenced, inactivated, or down-regulated, which first native gene encodes a first native enzyme involved in the metabolic production of an organic acid or a salt thereof, thereby increasing the native ability of said thermophilic or mesophilic microorganism to produce ethanol as a fermentation product. In certain embodiments, the aforementioned microorganism further comprises a first non-native gene, which first non-native gene encodes a first non-native enzyme involved in the metabolic production of ethanol. Another aspect of the invention relates to a process for converting lignocellulosic biomass to ethanol, comprising contacting lignocellulosic biomass with a genetically modified thermophilic or mesophilic microorganism.

Abstract: One aspect of the invention relates to a genetically modified thermophilic or mesophilic microorganism, wherein a first native gene is partially, substantially, or completely deleted, silenced, inactivated, or down-regulated, which first native gene encodes a first native enzyme involved in the metabolic production of an organic acid or a salt thereof, thereby increasing the native ability of said thermophilic or mesophilic microorganism to produce ethanol as a fermentation product. In certain embodiments, the aforementioned microorganism further comprises a first non-native gene, which first non-native gene encodes a first non-native enzyme involved in the metabolic production of ethanol. Another aspect of the invention relates to a process for converting lignocellulosic biomass to ethanol, comprising contacting lignocellulosic biomass with a genetically modified thermophilic or mesophilic microorganism.

Abstract: Mutant thermophilic organisms that consume a variety of biomass derived substrates are disclosed herein. Strains of Thermoanaerobacterium saccharolyticum with acetate kinase and phosphotransacetylase expression eliminated are disclosed herein. Further, strain ALK1 has been engineered by site directed homologous recombination to knockout both acetic acid and lactic acid production. Continuous culture involving a substrate concentration challenge lead to evolution of ALK1, and formation of a more robust strain designated ALK2. The organisms may be utilized for example in thermophilic SSF and SSCF reactions performed at temperatures that are optimal for cellulase activity to produce near theoretical ethanol yields without expressing pyruvate decarboxylase.

Abstract: Aspects of the present invention relate to methods of microbially treating lignocellulosic biomass using cellulose- and/or hemicellulose-degrading bacteria. In certain embodiments, the microbially treated material is then subjected to thermal and/or chemical pretreatment. In tandem with the microbial treatment the thermal and/or chemical pretreatment may result in the production of fewer degradation products, thereby allowing for higher overall yields of ethanol per ton of starting biomass.

Abstract: One aspect of the invention relates to a genetically modified thermophilic or mesophilic microorganism, wherein a first native gene is partially, substantially, or completely deleted, silenced, inactivated, or down-regulated, which first native gene encodes a first native enzyme involved in the metabolic production of an organic acid or a salt thereof, thereby increasing the native ability of said thermophilic or mesophilic microorganism to produce ethanol as a fermentation product. In certain embodiments, the aforementioned microorganism further comprises a first non-native gene, which first non-native gene encodes a first non-native enzyme involved in the metabolic production of ethanol. Another aspect of the invention relates to a process for converting lignocellulosic biomass to ethanol, comprising contacting lignocellulosic biomass with a genetically modified thermophilic or mesophilic microorganism.

Abstract: Mutant thermophilic organisms that consume a variety of biomass derived substrates are disclosed herein. Strains of Thermoanaerobacterium saccharolyticum with acetate kinase and phosphotransacetylase expression eliminated are disclosed herein. Further, strain ALK1 has been engineered by site directed homologous recombination to knockout both acetic acid and lactic acid production. Continuous culture involving a substrate concentration challenge lead to evolution of ALK1, and formation of a more robust strain designated ALK2. The organisms may be utilized for example in thermophilic SSF and SSCF reactions performed at temperatures that are optimal for cellulase activity to produce near theoretical ethanol yields without expressing pyruvate decarboxylase.