Process for producing fermentation products and fermentation medium compositions therefor

Abstract

Fermentation products (e.g., bio-products such as hydrocarbons and other organic compounds) are produced from biomass or gases through digestion and fermentation under conditions that thermodynamically favor production of the fermentation products.

What is claimed is: 
     
         1 . A method for producing C 2  to C 10  hydrocarbons, comprising: (a) producing carboxylic acids by fermenting a broth in a fermentation vessel, wherein the fermentation vessel comprises at least 0.001 atmospheres of H 2  gas; and (b) converting the carboxylic acids to the hydrocarbons. 
     
     
         2 . The method of  claim 1 , wherein the hydrocarbons comprise an alkane, alkene, or alkyne. 
     
     
         3 . The method of  claim 1 , wherein the hydrocarbons comprise an alkane from among butane, pentane, hexane, heptane, or octane. 
     
     
         4 . The method of  claim 1  wherein the carboxylic acids are converted to the hydrocarbons by fermenting the carboxylic acids with a microorganism that produces the hydrocarbons from the carboxylic acids. 
     
     
         5 . The method of  claim 4 , wherein the microorganism decarboxylates the carboxylic acids to produce the hydrocarbons and carbon dioxide. 
     
     
         6 . The method of  claim 4 , wherein the microorganism hydrogenates the carboxylic acids to produce the hydrocarbons. 
     
     
         7 . The method of  claim 1 , wherein the carboxylic acids are converted to the hydrocarbons using a chemical or electrochemical method. 
     
     
         8 . The method of  claim 1 , wherein the carboxylic acids are converted to the hydrocarbons using Kolbe electrolysis. 
     
     
         9 . The method of  claim 1 , wherein a source of H 2  gas is added to the fermentation vessel to increase partial pressure of H 2  gas in the fermentation vessel to at least 0.05 atmospheres. 
     
     
         10 . The method of  claim 1 , wherein a source of H 2  gas in the fermentation vessel is electrolysis using an electrode in the broth. 
     
     
         11 . The method of  claim 1 , wherein total gas pressure in the fermentation vessel is greater than 1 atmosphere. 
     
     
         12 . The method of  claim 1 , wherein a microorganism in the broth produces at least 1% C 4  to C 6  carboxylic acids by volume of broth. 
     
     
         13 . The method of  claim 1 , wherein the broth pH is increased to at least 6 by addition of a base or a buffer to neutralize produced carboxylic acids, and volume of carboxylic acids reaches at least 2% of the broth volume. 
     
     
         14 . The method of  claim 1 , further comprising the steps: infusing a gaseous substrate into the broth, wherein the gaseous substrate comprises H 2  gas and at least one gas from among CO 2  and CO; wherein the microorganisms ferment the gaseous substrate to produce C 2  to C 10  carboxylic acids; and volume of the C 2  to C 10  carboxylic acids reaches at least 1% of the broth volume. 
     
     
         15 . A method for producing C 2  to C 10  hydrocarbons, comprising: (a) producing carboxylic acids by fermenting a broth in a fermentation vessel, wherein volume of carboxylic acids reaches at least 2% of the both volume; and (b) converting the carboxylic acids to the hydrocarbons. 
     
     
         16 . The method of  claim 15 , wherein the volume of the carboxylic acids reaches at least 3% of the broth volume. 
     
     
         17 . The method of  claim 15 , wherein the broth comprises an isolated microorganism. 
     
     
         18 . The method of  claim 15 , wherein at least half of the volume of carboxylic acids produced in the fermentation broth has at least 4 carbon atoms per molecule. 
     
     
         19 . The method of  claim 15 , wherein methane-producing microorganisms are excluded from the broth or a methane inhibitor is added to the broth. 
     
     
         20 . The method of  claim 15 , further comprising the steps: fermenting an initial substrate in the broth to obtain an initial concentration of the carboxylic acids; and adding and fermenting a different substrate in the broth, wherein the different substrate is fermented to produce a higher concentration of the carboxylic acids. 
     
     
         21 . A method for producing C 6  to C 10  hydrocarbons, comprising: (a) fermenting a broth in a fermentation vessel, wherein the broth comprises a microorganism that produces C 4  to C 6  carboxylic acids; (b) adding a source of H 2  gas to the fermentation vessel to increase partial pressure of H 2  gas in the fermentation vessel to at least 0.001 atmospheres; (c) wherein the partial pressure of H 2  gas in the fermentation vessel shifts thermodynamic equilibrium in favor of producing a higher concentration of the C 4  to C 6  carboxylic acids; (d) wherein C 4  to C 6  carboxylic acids reach a volume of at least 1% of the broth volume; and (e) subjecting the broth to Kolbe electrolysis thereby converting the C 4  to C 6  carboxylic acids in the broth to the C 6  to C 10  hydrocarbons.