    3.1.3.37 | biofuel production |
engineered cyanobacteria with enhanced growth show increased ethanol production and higher biofuel to biomass ratio. Speeding up the Calvin-Benson-Bassham cycle theoretically has positive effects on the subsequent growth and/or the end metabolite(s) production. Four Calvin-Benson-Bassham cycle enzymes, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), fructose-1,6/sedoheptulose-1,7-bisphosphatase (FBP/SBPase), transketolase (TK) and aldolase (FBA) are selected to be cooverexpressed with the ethanol synthesis enzymes pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) in the cyanobacterium Synechocystis PCC 6803. An inducible promoter, PnrsB, is used to drive pyruvate decarboxylase and alcohol dehydrogenase expression. When PnrsB is induced and cells are cultivated at 0.065 mM photons/m*s, the RuBisCO-, FBP/SBPase-, TK-, and FBA-expressing strains produce 55%, 67%, 37% and 69% more ethanol and 7.7%, 15.1%, 8.8% and 10.1% more total biomass (the sum of dry cell weight and ethanol), respectively, compared to the strain only expressing the ethanol biosynthesis pathway. The ethanol to total biomass ratio is also increased in Calvin-Benson-Bassham cycle enzymes overexpressing strains. Using the cells with enhanced carbon fixation, when the product synthesis pathway is not the main bottleneck, can significantly increase the generation of a product (exemplified with ethanol), which acts as a carbon sink |
748559 |
| 3.1.3.37 | biotechnology |
antisense transgenic plants, in mature, fully expanded leaves, enzyme activity is closely related with photosynthetic capacity, in youngest leaves, photosynthetic rates are close to or higher than those of wild type plants, decreased enzymic activity also leads to reduction in carbohydrate levels, particularly in starch |
653517 |
