The present invention provides a method of enhancing continuous directional high-value biological conversion of an urban wet garbage open system. The method includes wet garbage crushing, low-energy consumption hydrolysis, continuous conversion of organic components of wet garbage into short-chain fatty acid, continuous directional conversion of other components of short-chain fatty acid into acetic acid, separation and microbial reflux of acetic acid, and the like. In this method, by crushing wet garbage, performing low-energy consumption hydrolysis, and seeding acclimatized activated sludge, two stages of anaerobic fermentations are carried out to firstly convert organic components of the wet garbage continuously into short-chain fatty acid, and then continuously and directionally convert other components of short-chain fatty acid into acetic acid, so as to realize continuous directional high-value biological conversion of the urban wet garbage in an open system without adding pure microbes and a large amount of chemicals.

The present invention provides a method of enhancing continuous directional high-value biological conversion of an urban wet garbage open system. The method includes wet garbage crushing, low-energy consumption hydrolysis, continuous conversion of organic components of wet garbage into short-chain fatty acid, continuous directional conversion of other components of short-chain fatty acid into acetic acid, separation and microbial reflux of acetic acid, and the like. In this method, by crushing wet garbage, performing low-energy consumption hydrolysis, and seeding acclimatized activated sludge, two stages of anaerobic fermentations are carried out to firstly convert organic components of the wet garbage continuously into short-chain fatty acid, and then continuously and directionally convert other components of short-chain fatty acid into acetic acid, so as to realize continuous directional high-value biological conversion of the urban wet garbage in an open system without adding pure microbes and a large amount of chemicals.

Provided is a method of producing a product by culturing a carboxydotrophic acetogenic bacterium with a disrupting mutation in a lactate dehydrogenase enzyme in the presence of a substrate comprising CO, CO.sub.2, and/or H.sub.2. Preferably, the disrupting mutation reduces or eliminates the expression or activity of the enzyme such that the bacterium produces a reduced amount of lactate or no lactate.

Provided is a method of producing a product by culturing a carboxydotrophic acetogenic bacterium with a disrupting mutation in a lactate dehydrogenase enzyme in the presence of a substrate comprising CO, CO.sub.2, and/or H.sub.2. Preferably, the disrupting mutation reduces or eliminates the expression or activity of the enzyme such that the bacterium produces a reduced amount of lactate or no lactate.

Disclosed are methods related to culturing anaerobic bacteria in a microaerobic environment. The method comprises culturing in a microaerobic environment an anaerobic bacteria with an aerobic microorganism. The microaerobic environment may not require gas pre-treatment to remove trace O.sub.2. Also disclosed are methods related to producing a product, syngas fermentation, and gas valorization. The method comprises culturing in a microaerobic environment an anaerobic bacteria with an aerobic microorganism.

The inventive biorefinery system and method accepts municipal solid waste, sewage sludges, and/or ag-wastes and processes it through three primary conversion unit operations to produce a variety of value-added products. In a preferred embodiment, the three primary conversion units are gasification, thermal depolymerization or torrefaction/pyrolysis, and biotreatment.

Provided is a method which enables efficient separation of a component such as microorganisms from an organic substance-containing liquid obtained by microbial fermentation. Disclosed is a method for producing an organic substance comprising a microbial fermentation step of obtaining an organic substance-containing liquid and a separation step of heating the organic substance-containing liquid and separating into a liquid or solid component containing microorganisms and a gaseous component containing the organic substance.

What is described is an integrated steel mill and a bioreactor configured to produce useful products from the waste stream of the steel mill. A waste gas stack which is connected to the steel mill is connected to a heat exchanger to cool the waste gas from the steel mill. The cooled gas is pressurized using a pressurization apparatus connected to the heat exchanger. The pressurized gas is sent to an oxygen removal apparatus connected to the pressurization apparatus. An oxygen depleted waste stream from the oxygen removal apparatus is passed to a bioreactor (connected to the oxygen removal apparatus) where microorganisms ferment the waste stream to products. Optional apparatus such as scrubbers, valves, buffers, are also disclosed. The products of the fermentation in the bioreactor can be ethanol and or acetate.

What is described is an integrated steel mill and a bioreactor configured to produce useful products from the waste stream of the steel mill. A waste gas stack which is connected to the steel mill is connected to a heat exchanger to cool the waste gas from the steel mill. The cooled gas is pressurized using a pressurization apparatus connected to the heat exchanger. The pressurized gas is sent to an oxygen removal apparatus connected to the pressurization apparatus. An oxygen depleted waste stream from the oxygen removal apparatus is passed to a bioreactor (connected to the oxygen removal apparatus) where microorganisms ferment the waste stream to products. Optional apparatus such as scrubbers, valves, buffers, are also disclosed. The products of the fermentation in the bioreactor can be ethanol and or acetate.

Described herein are methods, microbial cell lines, and media used in co-culture to augment propionic acid production using an optimized fermentation medium and methods for increasing propionic acid yield, e.g., by co-culturing Lacticbacillus Casei and high-acid tolerant A. Acidipropionici.