Bacteria to Destroy Greenhouse Gases
Any CO2 uptake by the bacteria will be balanced by respiration of the living bacteria and decomposition of the bacteria when they die. The only way to truly remove this carbon from the carbon cycle (and by extension the atmosphere) is to put the carbon in a location where it will not be able to enter the atmosphere. The use of bacteria as a storage device for carbon emissions does not even begin to be a reasonable solution. Carbon remains in soda cans longer than it remains in a cyanobacteria cell.
If we were really out to get rid of CO2 in the atmosphere, we would grow millions of tons of vegetation and plankton in shallow inland seas and then bury the material under sediment before it could decompose. Then we would just have to remember not to dig it up a couple of million years later and set it all on fire... Doh.