『Abstract
In order to determine the mechanisms by which fungi weather potassium-bearing
minerals on a molecular level, we prepared differential expression
cDNA libraries of Aspergillus fumigatus using suppression
subtractive hybridization (SSH) technology. The specimens were
cultured with and without potassium-bearing minerals. Among genes
that were upregulated by the presence of these minerals, 24% were
found to be involved in carbon source consumption. Of downregulated
genes, 54% were found to code for membrane proteins. This study
showed that the factors that could accelerate weathering of K-bearing
minerals involved organic acids, carbonic acid, and redox participant
molecules. K-bearing minerals were found to upregulate the expression
of carbonic anhydrase (CA), implying that A. fumigatus
was capable of converting CO2 into carbonate
to accelerate the weathering of potassium-bearing minerals, which
fixed CO2. During mineral weathering, the
fungus changed its metabolism, produced more metal-binding proteins,
and reduced membrane metal transporter expression, which can modulate
ion absorption and disposal and promote acid production. The results
of this study may improve our understanding of the mechanisms
by which microorganisms weather silicate minerals. Because silicate
weathering consumes CO2, the current study
provides molecular evidence for the participation of microorganisms
in silicate weathering and carbonate formation.
Keywords: Microbial weathering; Potassium-release; Carbonic anhydrase
(CA); Carbon dioxide sequestration; Silicate mineral carbonation』
1. Introduction
2. Materials and methods
2.1. Fungus
2.2. Minerals
2.3. Fungal cultures
2.4. RNA extraction
2.5. Suppression subtractive hybridization (SSH) library
2.6. Cloning and sequencing
2.7. DNA sequence analysis
2.8. Quantitative real time PCR
2.9. Effects of certain related factors on the release of K from
minerals
3. Results and discussion
3.1. Organic acids
3.2. Carbonic anhydrase
3.3. Oxidoreduction
3.4. Stress response
4. Conclusion
Acknowledgments
References