Methods and Compositions for Production of Methane Gas

Abstract

The present invention provides methods and compositions for sustained methane production from atmospheric CO 2 and solar energy from the sun. In general the methods involve culturing cyanobacteria in a first culture vessel and collecting and diverting the photosynthesis products, including glucose or acetic acid, to a second culture vessel including methanogenic bacteria. The photosynthesis products are then used as nutrients by the methanogenic bacteria in the second culture vessel in the production of methane. The methane produced is subsequently collected and used as a clean energy source. The invention also features compositions, including genetically modified cyanobacteria and systems for use in the methods of the invention.

1 . A method for production of methane, comprising
 culturing a photosynthetic organism in a first vessel in the presence of carbon dioxide (CO 2 ) and visible light, wherein the culturing provides for photosynthetic fixation of CO 2  to photosynthetic products,   collecting and diverting the photosynthesis product to a second vessel comprising methanogenic bacteria, and   culturing said methanogenic bacteria to produce methane.   
     
     
         2 . The method of  claim 1 , wherein said photosynthetic organism is a photosynthetic cyanobacteria. 
     
     
         3 . The method of  claim 1 , wherein said photosynthesis product is glucose or acetic acid. 
     
     
         4 . The method of  claim 2 , wherein the cyanobacteria is genetically modified in order to provide for transport of the photosynthetic products. 
     
     
         5 . The method of  claim 1 , wherein visible light source is natural light. 
     
     
         6 . The method of  claim 1 , wherein a visible light source is artificial light. 
     
     
         7 . The method of  claim 1 , wherein a CO 2  source is atmospheric CO 2 . 
     
     
         8 . The method of  claim 1 , wherein a CO 2  source is an artificial source. 
     
     
         9 . A system for production of methane, comprising
 a first vessel for culturing a photosynthetic organism in the presence of carbon dioxide (CO 2 ) and visible light, and   a second enclosed vessel for culturing methanogenic bacteria,   wherein said first vessel is in fluid communication with said second vessel.   
     
     
         10 . The system of  claim 9 , wherein visible light source is natural light. 
     
     
         11 . The system of  claim 9 , wherein a visible light source is artificial light. 
     
     
         12 . The system of  claim 9 , wherein a CO 2  source is atmospheric CO 2 . 
     
     
         13 . The system of  claim 9 , wherein a CO 2  source is an artificial source. 
     
     
         14 . The system of  claim 9 , further comprising a first conduit connecting the first vessel and the second vessel. 
     
     
         15 . The system of  claim 9 , further comprising a gas storage container in gaseous communication with the second vessel. 
     
     
         16 . The system of  claim 15 , further comprising a second conduit connecting the second vessel with the gas storage container. 
     
     
         17 . A genetically modified cyanobacteria expressing at least a first foreign gene, wherein the genetically modified cyanobacteria is capable of transporting products of photosynthesis across the cyanobacteria's membrane. 
     
     
         18 . The genetically modified cyanobacteria of  claim 17 , wherein the transport is passive transport. 
     
     
         19 . The genetically modified cyanobacteria of  claim 17 , wherein the transport is active transport. 
     
     
         20 . The genetically modified cyanobacteria of  claim 17 , wherein the first foreign gene encodes a glucose transporter. 
     
     
         21 . The genetically modified cyanobacteria of  claim 17 , wherein the glucose transporter is Glut-1. 
     
     
         22 . The genetically modified cyanobacteria of  claim 17 , wherein the genetically modified cyanobacteria expresses a second foreign gene. 
     
     
         23 . The genetically modified cyanobacteria of  claim 22 , wherein the first foreign gene encodes fructose-6-phosphate and the second foreign gene encodes glucose-6-phosphatase. 
     
     
         24 . The genetically modified cyanobacteria of  claim 22 , wherein the first foreign gene encodes pyruvate decarboxylase and the second foreign gene encodes aldehyde dehydrogenase. 
     
     
         25 . The genetically modified cyanobacteria of  claim 22 , wherein the first foreign gene encodes pyruvate dehydrogenase and the second foreign gene encodes acetyl CoA kinase.