The present invention relates to a dry grind ethanol process in which post-distillation backset is subjected to aerobic fermentation to remove components that are inhibitory to an ethanolagen, such as yeast, allowing the utilization of an increased amount of post-distillation backset during the initial preparation of starch-containing substrates for the dry grind ethanol process. Aerobic fermentation of the post-distillation backset allows substantially higher backset recycle, resulting in fresh water savings and increased sustainability.

The present invention relates to a dry grind ethanol process in which post-distillation backset is subjected to aerobic fermentation to remove components that are inhibitory to an ethanolagen, such as yeast, allowing the utilization of an increased amount of post-distillation backset during the initial preparation of starch-containing substrates for the dry grind ethanol process. Aerobic fermentation of the post-distillation backset allows substantially higher backset recycle, resulting in fresh water savings and increased sustainability.

What is disclosed is a biorefining process to co-produce xylitol with ethanol or other products. In some variations, a process for producing ethanol and xylitol from lignocellulosic biomass, comprises: extracting hemicelluloses from lignocellulosic biomass, wherein the hemicelluloses include xylose oligomers and other sugar oligomers; hydrolyzing the xylose oligomers and the other sugar oligomers, using an acid catalyst or enzymes, to generate xylose and other sugar monomers, respectively; fermenting the other sugar monomers to ethanol using a suitable ethanol-producing microorganism; removing at least some of the ethanol (to increase concentration of xylose); fermenting the xylose to xylitol using a suitable xylitol-producing microorganism; and recovering the xylitol at high concentration.

What is disclosed is a biorefining process to co-produce xylitol with ethanol or other products. In some variations, a process for producing ethanol and xylitol from lignocellulosic biomass, comprises: extracting hemicelluloses from lignocellulosic biomass, wherein the hemicelluloses include xylose oligomers and other sugar oligomers; hydrolyzing the xylose oligomers and the other sugar oligomers, using an acid catalyst or enzymes, to generate xylose and other sugar monomers, respectively; fermenting the other sugar monomers to ethanol using a suitable ethanol-producing microorganism; removing at least some of the ethanol (to increase concentration of xylose); fermenting the xylose to xylitol using a suitable xylitol-producing microorganism; and recovering the xylitol at high concentration.

Methods, compositions, and systems for propagation and fermentation, particularly large scale operations for production of ethanol and dried distiller's grain are provided. Addition of Z. mobilis to propagation and/or fermentation decreases lactic acid bacterial contamination.

The present invention can: efficiently and readily produce glucose from microalgae that accumulate starch in their cells; and obtain ethanol. During a preparation step of the glucose production method, microalgae are prepared on which a saccharifying enzyme acts on starch accumulated inside the microalgae cells, without disrupting the cell walls. In a saccharification step, starch inside the cells is saccharified and glucose is generated, by adding a saccharifying enzyme to the microalgae without a disruption treatment. The ethanol production method has a step in which, after the saccharification step, the glucose undergoes alcoholic fermentation and ethanol is generated.

The present invention can: efficiently and readily produce glucose from microalgae that accumulate starch in their cells; and obtain ethanol. During a preparation step of the glucose production method, microalgae are prepared on which a saccharifying enzyme acts on starch accumulated inside the microalgae cells, without disrupting the cell walls. In a saccharification step, starch inside the cells is saccharified and glucose is generated, by adding a saccharifying enzyme to the microalgae without a disruption treatment. The ethanol production method has a step in which, after the saccharification step, the glucose undergoes alcoholic fermentation and ethanol is generated.

Supplemented mixotrophic method. A mixotrophic fermentation method is disclosed including providing a naturally acetogenic organism; providing a fermentation medium comprising a carbon source and a supplemented non-sugar reductant; and culturing the organism in the fermentation medium, where both the carbon source and the non-sugar reductant are metabolized and a fermentation broth is formed, which contains at least one carbon-containing bioproduct.

Supplemented mixotrophic method. A mixotrophic fermentation method is disclosed including providing a naturally acetogenic organism; providing a fermentation medium comprising a carbon source and a supplemented non-sugar reductant; and culturing the organism in the fermentation medium, where both the carbon source and the non-sugar reductant are metabolized and a fermentation broth is formed, which contains at least one carbon-containing bioproduct.

The invention is directed to a process for producing one or more fermentation product in a multi-stage process including an inoculation reactor and at least one bioreactor. The inoculation reactor is fed a C1-containing gaseous substrate containing a reduced amount of hydrogen. The hydrogen is reduced to increase the proportion of CO in the C1-containing gaseous substrate being provided to the inoculation reactor. The inoculation reactor ferments the CO-rich C1-containing gaseous substrate and produces an inoculum, which is fed to at least one bioreactor. The bioreactor receives the C1-containing gaseous substrate, which may or may not contain reduced amounts of hydrogen, to produce one or more fermentation product. By providing a CO-rich C1-containing gaseous substrate to the inoculation reactor, both the inoculation reactor and the subsequent bioreactor(s), are able to have increased stability and product selectivity.