Urease producing microorganisms for coal dust suppression isolated from coal: Characterization and comparative study

Abstract

In order to promote the biomineralization technology application to the field of coal dust inhibition, two strains of urease producing bacteria from coal were screened in this study. They are X3 with extracellular enzyme and X4 with intracellular enzyme. The ITS and 16S rDNA sequencing showed that the strains X3 and X4 were highly similar to Aspergillus sydowii and Bacillus DB-6. Strains X3 and X4 had their maximum urease activity at the initial 0.5 M urea concentration and slightly alkaline (pH 8) and neutral (pH 7) initial pH, respectively. Their mineralized products have a spherical structure and conform to the elemental composition of calcium carbonate. The dust suppression effect showed that both X3 and X4 bacteria liquid can effectively bind coal dust to form coal dust consolidation bodies containing calcite and vaterite type calcium carbonate. Interestingly, the coal dust consolidation body treated with the strain X4 is more resistant to wind and rain. The screening, mineralization and dust suppression potential analysis of the two strains of urease bacteria provided empirical support for the application of microbial induced calcium carbonate precipitation technology in the coal dust suppression.