Production and Secretion of Glucose in Photosynthetic Prokaryotes (Cyanobacteria)

Abstract

The present invention includes compositions and methods for making and using an isolated cyanobacterium that includes a portion of an exogenous bacterial cellulose operon sufficient to express bacterial cellulose, whereby the cyanobacterium produces extracellular glucose. The compositions and methods of the present invention may be used as a new global crop for the manufacture of cellulose, CO 2 fixation, for the production of alternative sources of conventional cellulose as well as a biofuel and precursors thereof.

1 . An isolated cyanobacterium comprising a portion of an exogenous bacterial cellulose operon sufficient to express bacterial cellulose, whereby the cyanobacterium produces extracellular glucose. 
     
     
         2 . The cyanobacterium of  claim 1 , wherein the cyanobacteria is further defined as producing extracellular glucose and cellulose in the form of monosaccharides, disaccharides, oligosaccharides or polysaccharides from photosynthesis. 
     
     
         3 . The cyanobacterium of  claim 1 , wherein the cyanobacteria is further defined as making monosaccharides, disaccharides, oligosaccharides or polysaccharides that comprise glucose and cellulose. 
     
     
         4 . The cyanobacterium of  claim 1 , wherein the cyanobacterium comprises  Synechococcus  sp. PCC 7002,  Synechococcus leopoliensis  strain UTCC 100,  Agmenellum quadruplicatum  UTEX B2268,  Nostoc  spp.,  Anabaena  spp.,  Cyanothece  spp.,  Trichodesmium  spp. and  Synechococcus  sp. ATCC 27264. 
     
     
         5 . The cyanobacterium of  claim 1 , wherein the glucose, the cyanobacterial extracellular polysaccharides or both are further processed as a renewable feedstock for biofuel production. 
     
     
         6 . The cyanobacterium of  claim 1 , wherein the cyanobacterium can fix CO 2  while producing cellulose and reducing atmospheric CO 2 . 
     
     
         7 . The cyanobacterium of  claim 1 , wherein the cyanobacterium increases the extracellular production of monosaccharides, disaccharides, oligosaccharides or polysaccharides upon exposure to acidic conditions. 
     
     
         8 . The cyanobacterium of  claim 1 , wherein extracellular glucose is exuded from cells or released from extracellular polysaccharides by the actions of one or more endogenous secreted glycosyl hydrolases. 
     
     
         9 . An isolated cyanobacterium, comprising:
 a  Synechococcus  sp. comprising a portion of an exogenous bacterial cellulose operon sufficient to express bacterial cellulose, whereby the cyanobacterium is capable of producing extracellular monosaccharides, disaccharides, oligosaccharides or polysaccharides comprising glucose.   
     
     
         10 . The cyanobacterium of  claim 9 , wherein the cyanobacteria is further defined as producing extracellular glucose in the form of monosaccharides, disaccharides, oligosaccharides or polysaccharides from photosynthesis. 
     
     
         11 . The cyanobacterium of  claim 9 , wherein the cyanobacterium is further defined as making monosaccharides, disaccharides, oligosaccharides or polysaccharides that comprise glucose and cellulose. 
     
     
         12 . The cyanobacterium of  claim 9 , wherein the cyanobacterium comprises  Synechococcus  sp. PCC 7002,  Synechococcus leopoliensis  strain UTCC 100,  Agmenellum quadruplicatum  UTEX B2268,  Nostoc  spp.,  Anabaena  spp.,  Cyanothece  spp.,  Trichodesmium  spp., and  Synechococcus  sp. ATCC 27264. 
     
     
         13 . The cyanobacterium of  claim 9 , wherein the cellulose, the cyanobacterial extracellular polysaccharides or both are further processed as a renewable feedstock for biofuel production. 
     
     
         14 . The cyanobacterium of  claim 9 , wherein extracellular glucose is exuded from cells or released from extracellular polysaccharides by the actions of one or more endogenous secreted glycosyl hydrolases. 
     
     
         15 . A method of producing monosaccharides, disaccharides, oligosaccharides or polysaccharides comprising glucose, comprising:
 modifying a cyanobacterium with a portion of an exogenous bacterial cellulose operon sufficient to express and produce extracellular glucose;   growing the cyanobacteria under conditions that promote extracellular glucose production; and   exposing the cyanobacteria to an acidic condition, wherein the acid increases extracellular glucose production and optionally that the viable cells are returned to the growth medium after glucose harvest for continued production of cells, biomass, cellulose or glucose.   
     
     
         16 . The method of  claim 15 , further comprising the step of processing the glucose into ethanol. 
     
     
         17 . The method of  claim 15 , wherein the glucose is used as a renewable feedstock for biofuel production. 
     
     
         18 . The method of  claim 15 , wherein the cyanobacterium fixes CO 2  and thus atmospheric CO 2 . 
     
     
         19 . The method of  claim 15 , wherein the glucose is used as a renewable feedstock for animals. 
     
     
         20 . A method of fixing carbon into a photobiomass comprising:
 growing a cyanobacterium comprising a portion of an exogenous bacterial cellulose operon sufficient to make cellulose and to produce extracellular glucose in a CO 2 -containing growth medium;   generating glucose with said cyanobacterium, wherein CO 2  is fixed into glucose at a level higher than an unmodified cyanobacterium; and   calculating the amount of CO 2  fixed into the glucose to equate to one or more carbon credit units.   
     
     
         21 . The method of  claim 20 , wherein at least one other carbon is fixed into glucose and at least one other carbon's is equated to carbon credit units that is included in the calculation. 
     
     
         22 . An isolated cyanobacterium comprising a portion of an exogenous bacterial cellulose operon sufficient to express bacterial cellulose, whereby the cyanobacterium is capable of producing extracellular monosaccharides, disaccharides, oligosaccharides or polysaccharides.