CO2 sequestration by ureolytic microbial consortia through microbially-induced calcite precipitation

Abstract

Urea is an abundant nitrogen-containing compound found in urine of mammals and widely used in fertilizers. This compound is part of the nitrogen biogeochemical cycle and is easily biodegraded by ureolytic microorganisms that have the urease enzyme. Previous studies, with ureolytic isolates, have shown that some ureolytic microorganisms are able to sequester CO₂ through a process called microbially-induced calcium carbonate precipitation. The present study investigates 15 ureolytic consortia obtained from the "Pamukkale travertines" and the "Cave Without A Name" using different growth media to identify the possible bacterial genera responsible for CO₂ sequestration through the microbially-induced calcite precipitation (MICP). The community structure and diversity were determined by deep-sequencing. The results showed that all consortia presented varying CO₂ sequestration capabilities and MICP rates. The CO₂ sequestration varied between 0 and 86.4%, and it depended largely on the community structure, as well as on pH. Consortia with predominance of Comamonas, Plesiomonas and Oxalobacter presented reduced CO₂ sequestration. On the other hand, consortia dominated by Sporosarcina, Sphingobacterium, Stenotrophomonas, Acinetobacter, and Elizabethkingia showed higher rates of CO₂ uptake in the serum bottle headspace.

Keywords: Bacterial consortia; CO(2) sequestration; Cave; Microbially-induced carbonate precipitation; Travertine; Urease activity.