Abstract
It is widely recognized that carbonic anhydrase (CA) participates in silicate weathering and carbonate formation. Nevertheless, it is still not known if the magnitude of the effect produced by CA on surface rock evolution changes or not. In this work, CA gene expression from Bacillus mucilaginosus and the effects of recombination protein on wollastonite dissolution and carbonate formation under different conditions are explored. Real-time fluorescent quantitative PCR was used to explore the correlation between CA gene expression and sufficiency or deficiency in calcium and CO&sub2; concentration. The results show that the expression of CA genes is negatively correlated with both CO&sub2; concentration and ease of obtaining soluble calcium. A pure form of the protein of interest (CA) is obtained by cloning, heterologous expression, and purification. The results from tests of the recombination protein on wollastonite dissolution and carbonate formation at different levels of CO&sub2; concentration show that the magnitudes of the effects of CA and CO&sub2; concentration are negatively correlated. These results suggest that the effects of microbial CA in relation to silicate weathering and carbonate formation may have increased importance at the modern atmospheric CO&sub2; concentration compared to 3 billion years ago.