TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: In the method above, 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. The culturing of (a) and/or (b) is carried out in a fermentor. The culturing of (a) and of (b) is carried out in separate fermentors; optionally, where the culturing of (a) is carried out in an aerobic fermentor; and/or optionally, where the culturing of (b) is carried out in an anaerobic fermentor. The method further comprises contacting the first organism with an oxidizing agent, optionally, where the oxidizing agent is oxygen gas (O2); and/or contacting the second organism with a reducing agent, optionally, where the oxidizing agent is hydrogen gas (H2), carbon monoxide (CO), syngas, or hydrogen sulfide (H2S). The O2 and/or the H2 are generated by electrolysis of H2O. The culturing of (a) and/or (b) is carried out in a liquid medium; optionally, where O2 is dispersed in the liquid medium of the aerobic fermentor in the form of micro-bubbles; and/or optionally, where H2 is dispersed in the liquid medium of the anaerobic fermentor in the form of microbubbles. The method further comprises providing electrons to the organism of (b) by contacting the organism of (b) with an electric current. The carbon source is a carbohydrate; optionally, where the carbohydrate is glucose, fructose, ethanol, butanol, acetic acid, biomass, cellulose, or hemicellulose. A product of the carbon source oxidization process in (a) is a biofuels; a lipid; an edible lipid, or its precursor; 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). The organism of (a) and/or (b) is a microorganism. The organism of (a) is an oleaginous yeast, optionally, where the organism of (a) is Yarrowia lipolytica; and/or the organism of (b) is a CO2-fixing bacterium, optionally, where the organism of (b) is an acetogenic bacterium; and/or the organism of (a) and/or (b) is genetically modified, optionally, where the organism of (a) overexpresses a stearoyl-CoA desaturase (SCD) gene. Preferred Bioreactor: The aerobic and/or the anaerobic fermentor comprises a liquid medium; the aerobic fermentor comprises an oxidizing agent, optionally, where the oxidizing agent is O2 and/or the anaerobic fermentor comprises a reducing agent, optionally, where the reducing agent is H2, CO, syngas, or H2S. The bioreactor further comprises an electrolysis apparatus that generates O2 and H2 from H2O, where the O2 is delivered to the aerobic fermentor and/or the H2 is delivered to the anaerobic fermentor. The aerobic fermentor comprises O2 in the form of microbubbles and/or where the anaerobic fermentor comprises H2 in the form of micro-bubbles, and/or where 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 CO2. The aerobic fermentor further comprises an outflow through which the product of oxidizing the carbon source is removed. The inflow of (b)(ii) further connected to an external source of CO2. A product of CO2 reduction in the anaerobic fermentor is a carbon source that can be oxidized by the organism in the aerobic fermentor; a product of CO2 reduction in the anaerobic fermentor is biomass, cellulose, or hemi-cellulose; a product of CO2 reduction in the anaerobic fermentor is a biofuel; and/or a product of CO2 reduction in the anaerobic fermentor is ethanol or butanol. The anaerobic fermentor comprises an outflow through which a product of CO2 reduction is removed; optionally, where the outflow through which the product of CO2 reduction is removed from the anaerobic fermentor is connected to the aerobic fermentor and the product of CO2 reduction in the anaerobic fermentor is delivered to the aerobic fermentor; optionally, where the product of CO2 reduction in the anaerobic fermentor constitutes at least part of the carbon source in the aerobic fermentor. EXAMPLE - No suitable example given.