Cyanobacteria oxygen production

The importance of manganese for bacteria, such as that of Ni and to a lesser extent Co, as we saw in the last chapter, is considerable. Of course, as we will see shortly, it is also important in the tetranuclear Mn cluster that is involved in oxygen production in photosynthetic plants, algae and cyanobacteria, as well as in a number of mammalian enzymes such as arginase and mitochondrial superoxide dismutase. Most of manganese biochemistry can be explained on the one hand by its redox activity, and on the other by its analogy to Mg2+ (reviewed in Yocum and Pecoraro, 1999). 

The bathtub analogy can be used to consider many aspects of sequestration on the Earth. The most obvious problem, the storage of water in the oceans rather than the mantle, has already been discussed above. A similar problem is the sequestration of oxygen in the air. In the late Archaean Earth, the photosynthetic cause of the flow of oxygen production through the tap was presumably in cyanobacterial mats and global cyanobacterial plankton. This view is based on the evidence for the presence of cyanobacteria (Buick 1992). Bacteria spread very rapidly and once cyanobacteria had evolved they would have occupied every available niche very quickly. Just as rabbits filled Australia within a few decades, so cyanobacteria would spread globally within a very few years of their first evolution. If they are present in one place, they will be present planet-wide. 

The major role of manganese in biology is in oxygen production by photosynthetic plants, algae, and cyanobacteria. It is also involved in a number of mammalian enzymes like arginase and mitochondrial superoxide dismutase and it also plays an important role in microbial metabolism. Most of manganese biochemistry can be... 

What is not clear, however, is the precise cause of the rise in oxygen at between 2.3 and 2.4 Ga. It was not simply an increase in cyanobacterial oxygen production, because cyanobacteria had already been in existence for several hundred million years. Another, inorganic trigger is required - related perhaps to a change in the proportion of reducing volcanic gases produced, or to the way in which... 

Cyanobacteria were probably the first organisms to perform oxygenic photosynthesis resulting eventually in the oxidation of environmental Fe " to Fe " with all its consequences. To cope with this problem the production of siderophores was initiated. Not much is known about the siderophores of cyanobacteria. Schizokinen (see below under citrate siderophores, Sect. 4.1) (326) found to be produced by several bacterial species may have been acquired by gene transfer see however also the citrate siderophores synechobactins. 

---