Bioprocess and microbe engineering for total carbon utilization in biofuel production

Abstract

Some aspects of this invention provide methods and bioreactors for converting a carbon source into a lipid. In some embodiments, lipid production is carried out in an aerobic fermentor and carbon dioxide generated during lipid production is converted into a carbon substrate by CO 2 fixation in an anaerobic fermentor. In some embodiments, the carbon substrate generated by CO2 fixation is used as the carbon source for lipid production, thus achieving total carbon utilization in lipid production.

1 . A method comprising
 (a) culturing a first organism in the presence of a carbon source under conditions suitable for the organism to oxidize the carbon source, wherein the organism produces CO 2  as part of the oxidation process; and   (b) culturing a second organism in the presence of CO 2  produced in (a) under conditions suitable for the second organism to reduce the CO 2 , wherein the organism produces a carbon substrate as part of the reduction process.   
     
     
         2 . The method of  claim 1 , wherein
 the conditions of (a) are oxidizing conditions;   the conditions of (a) are aerobic conditions;   the conditions of (b) are reducing conditions; and/or   the conditions of (b) are anaerobic conditions.   
     
     
         3 .- 5 . (canceled) 
     
     
         6 . The method of  claim 1 , wherein the culturing of (a) and/or (b) is carried out in a fermentor. 
     
     
         7 . The method of  claim 1 , wherein
 the culturing of (a) and of (b) is carried out in separate fermentors;
 optionally, wherein the culturing of (a) is carried out in an aerobic fermentor; and/or 
 optionally, wherein the culturing of (b) is carried out in an anaerobic fermentor. 
   
     
     
         8 .- 9 . (canceled) 
     
     
         10 . The method of  claim 1 , further comprising
 contacting the first organism with an oxidizing agent,
 optionally, wherein the oxidizing agent is O 2 ; and/or 
   contacting the second organism with a reducing agent,
 optionally, wherein the oxidizing agent is H 2 , CO, syngas, or H 2 S. 
   
     
     
         11 .- 13 . (canceled) 
     
     
         14 . The method of  claim 10 , wherein the O 2  and/or the H 2  are generated by electrolysis of H 2 O. 
     
     
         15 . (canceled) 
     
     
         16 . The method of  claim 7 , wherein
 the culturing of (a) and/or (b) is carried out in a liquid medium;
 optionally, wherein O 2  is dispersed in the liquid medium of the aerobic fermentor in the form of micro-bubbles; and/or 
 optionally, wherein H 2  is dispersed in the liquid medium of the anaerobic fermentor in the form of micro-bubbles. 
   
     
     
         17 . The method of  claim 1 , further comprising providing electrons to the organism of (b) by contacting the organism of (b) with an electric current. 
     
     
         18 . (canceled) 
     
     
         19 . The method of  claim 1 , wherein the carbon source is a carbohydrate; optionally, wherein the carbohydrate is glucose, fructose, ethanol, butanol, acetic acid, biomass, cellulose, or hemicellulose. 
     
     
         20 . (canceled) 
     
     
         21 . The method of  claim 1 , wherein
 a product of the carbon source oxidization process in (a) is a biofuels; a lipid; an edible lipid, or a precursor thereof;   the carbon substrate produced in (b) is a biofuel; ethanol; biomass; cellulose; or hemi-cellulose;   the carbon substrate produced in (b) is a carbon source that can be oxidized by the organism of (a); and/or   the carbon source of (a) comprises at least part of the carbon substrate produced in (b).   
     
     
         22 .- 32 . (canceled) 
     
     
         33 . The method of  claim 1 , wherein the organism of (a) and/or (b) is a microorganism. 
     
     
         34 . The method of  claim 1 , wherein
 the organism of (a) is an oleaginous yeast,
 optionally, wherein the organism of (a) is  Y. lipolytica ; and/or the organism of (b) is a CO 2 -fixing bacterium, 
 optionally, wherein the organism of (b) is an acetogenic bacterium; and/or the organism of (a) and/or (b) is genetically modified, 
 optionally, wherein the organism of (a) overexpresses an SCD gene. 
   
     
     
         35 .- 40 . (canceled) 
     
     
         41 . A bioreactor comprising
 (a) an aerobic fermentor, the aerobic fermentor comprising
 (i) a carbon source, 
 (ii) an organism oxidizing the carbon source and generating CO 2 ; and 
 (iii) an outflow, through which the CO 2  is removed from the fermentor; 
   (b) an anaerobic fermentor comprising
 (i) an organism reducing CO 2 , and 
 (ii) an inflow providing CO 2  to the fermentor, wherein the inflow is connected to the outflow of (a)(iii). 
   
     
     
         42 . The bioreactor of  claim 41 , wherein
 the aerobic and/or the anaerobic fermentor comprises a liquid medium;   the aerobic fermentor comprises an oxidizing agent,
 optionally, wherein the oxidizing agent is O f  and/or 
   the anaerobic fermentor comprises a reducing agent,
 optionally, wherein the reducing agent is H 2 , CO, syngas, or H 2 S. 
   
     
     
         43 .- 44 . (canceled) 
     
     
         45 . The bioreactor of  claim 41 , further comprising an electrolysis apparatus that generates O2 and H2 from H2O, wherein the O2 is delivered to the aerobic fermentor and/or the H2 is delivered to the anaerobic fermentor. 
     
     
         46 . The bioreactor of  claim 41 ,
 wherein the aerobic fermentor comprises O2 in the form of microbubbles and/or wherein the anaerobic fermentor comprises H2 in the form of micro-bubbles, and/or   wherein the anaerobic fermentor comprises one or more electrodes delivering an electric current to the fermentor in an amount sufficient to provide the organism in the anaerobic fermentor with electrons for CO 2 .   
     
     
         47 . (canceled) 
     
     
         48 . The bioreactor of any of  claim 41 , wherein
 the carbon source is glucose, fructose, ethanol, butanol, acetic acid, biomass, cellulose, or hemicellulose;   a product of oxidizing the carbon source is a biofuel; and/or   a product of oxidizing the carbon source is a lipid.   
     
     
         49 .- 51 . (canceled) 
     
     
         52 . The bioreactor of  claim 41 , wherein the aerobic fermentor further comprises an outflow through which the product of oxidizing the carbon source is removed. 
     
     
         53 . The bioreactor of  claim 41 , wherein the inflow of (b)(ii) is further connected to an external source of CO 2 . 
     
     
         54 . The bioreactor of  claim 41 , wherein
 a product of CO 2  reduction in the anaerobic fermentor is a carbon source that can be oxidized by the organism in the aerobic fermentor;   a product of CO 2  reduction in the anaerobic fermentor is biomass, cellulose, or hemi-cellulose;   a product of CO 2  reduction in the anaerobic fermentor is a biofuel; and/or   a product of CO 2  reduction in the anaerobic fermentor is ethanol or butanol.   
     
     
         55 .- 57 . (canceled) 
     
     
         58 . The bioreactor of  claim 41 , wherein
 the anaerobic fermentor comprises an outflow through which a product of CO 2  reduction is removed;
 optionally, wherein the outflow through which the product of CO 2  reduction is removed from the anaerobic fermentor is connected to the aerobic fermentor and the product of CO 2  reduction in the anaerobic fermentor is delivered to the aerobic fermentor;
 optionally, wherein the product of CO 2  reduction in the anaerobic fermentor constitutes at least part of the carbon source in the aerobic fermentor. 
 
   
     
     
         59 .- 62 . (canceled) 
     
     
         63 . The bioreactor of  claim 41 , wherein the organism of (a) and/or (b) is a microorganism;
 optionally, wherein the organism of (a) is an oleaginous yeast;
 optionally, wherein the organism of (a) is  Y. lipolytica;    
   optionally, wherein the organism of (b) is a CO 2 -fixing bacterium;
 optionally, wherein the organism of (b) is an acetogenic bacterium; and/or 
   the organism of (a) and/or (b) is genetically modified;
 optionally, wherein the organism of (a) overexpresses an SCD gene. 
   
     
     
         64 .- 71 . (canceled)