The different roles of Aspergillus nidulans carbonic anhydrases in wollastonite weathering accompanied by carbonation

The microbial weathering of silicate minerals is an important part of the elemental biogeochemical cycle on Earth. It can even affect the migration and transformation of carbon, a process in which microbial carbonic anhydrase (CA) plays an important role. However, whether multiple microbial CAs are involved in silicate weathering and carbonation is still poorly understood. In this work, gene deletion, overexpression, and bioinformatics were used to reveal the functional differences that two Aspergillus nidulans CA genes, canA and canB, have in wollastonite weathering. The results show that canA is involved in silicate weathering and can be accompanied by carbonation. However, canB is indispensable for the survival of A. nidulans in present ambient conditions (c. 0.04% CO2, v/ v), where it is mainly obligated to cellular respiration and biosynthesis. This study highlights the contribution of microbial CAs to regulating the atmospheric CO2 cycle through silicate mineral bio-weathering. It also presents a potential application of sequestration of CO2 via biochemical weathering. (C) 2018 Elsevier Ltd. All rights reserved.