Microbial precipitation of calcium carbonate is a widespread environmental phenomenon that has diverse engineering applications, from building and soil restoration to carbon sequestration. Urease-mediated ureolysis and CO2 (de)hydration by carbonic anhydrase (CA) are known for their potential to precipitate carbonate minerals, yet many environmental microbial community studies rely on marker gene or metagenomic approaches that are unable to determine in situ activity. Here, we developed fast and cost-effective tests for the field detection of urease and CA activity using pH-sensitive strips inside microcentrifuge tubes that change colour in response to the reaction products of urease (NH3) and CA (CO2). The urease assay proved sensitive and useful in the field to detect in situ activity in biofilms from a saline lake, a series of calcareous fens, and ferrous springs, finding relatively high urease activity in lake samples. Incubations of lake microbes with urea resulted in significantly higher CaCO3 precipitation compared to incubations with a urease inhibitor, showing that the rapid assay indicated an on-site active metabolism potentially mediating carbonate precipitation. The CA assay, however, showed less sensitivity compared to the urease test. While its sensitivity limits its utility, the assay may still be useful as a preliminary indicator given the paucity of other means for detecting CA activity in the field. Field urease, and potentially CA, activity assays complement molecular approaches and facilitate the search for carbonate-precipitating microbes and their in situ activity, which could be applied toward agriculture, engineering and carbon sequestration technologies.
Bibliographical noteFunding Information:
This research was funded by a NASA award NNX14AK20G to JVB. FMF acknowledges the UMN Graduate School DDF, Fulbright 15150776 and CONICYT folio-72160214 fellowships. KH was supported by a MnDRIVE Environment initiative grant at the University of Minnesota. We thank Michael Rosen, Matt Oberhelman, Kim Lapakko, Beverly Flood, Javier Garc?a Barriocanal and Barbara MacGregor for field/laboratory support and discussions. We also thank the anonymous reviewers for helpful suggestions to improve the quality of this manuscript. The authors declare no conflict of interest. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. This research was funded by a NASA award NNX14AK20G to JVB. FMF acknowledges the UMN Graduate School DDF, Fulbright 15150776 and CONICYT folio-72160214 fellowships. KH was supported by a MnDRIVE Environment initiative grant at the University of Minnesota.
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.