title: Microbial growth under supercritical CO2.
abstract: Growth of microorganisms in environments containing CO2 above its critical point is unexpected due to a combination of deleterious effects, including cytoplasmic acidification and membrane destabilization. Thus, supercritical CO2 (scCO2) is generally regarded as a sterilizing agent. We report isolation of bacteria from three sites targeted for geologic carbon dioxide sequestration (GCS) that are capable of growth in pressurized bioreactors containing scCO2. Analysis of 16S rRNA genes from scCO2 enrichment cultures revealed microbial assemblages of varied complexity, including representatives of the genus Bacillus. Propagation of enrichment cultures under scCO2 headspace led to isolation of six strains corresponding to Bacillus cereus, Bacillus subterraneus, Bacillus amyloliquefaciens, Bacillus safensis, and Bacillus megaterium. Isolates are spore-forming, facultative anaerobes and capable of germination and growth under an scCO2 headspace. In addition to these isolates, several Bacillus type strains grew under scCO2, suggesting that this may be a shared feature of spore-forming Bacillus spp. Our results provide direct evidence of microbial activity at the interface between scCO2 and an aqueous phase. Since microbial activity can influence the key mechanisms for permanent storage of sequestered CO2 (i.e., structural, residual, solubility, and mineral trapping), our work suggests that during GCS microorganisms may grow and catalyze biological reactions that influence the fate and transport of CO2 in the deep subsurface.
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors: Kyle C
authors: KC
authors: Peet
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors: Adam J E
authors: AJ
authors: Freedman
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors: Hector H
authors: HH
authors: Hernandez
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors: Vanya
authors: V
authors: Britto
authors: Geoscience Australia, Canberra, ACT, Australia CO2CRC, Canberra, ACT, Australia.
authors: Chris
authors: C
authors: Boreham
authors: Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California.
authors: Jonathan B
authors: JB
authors: Ajo-Franklin
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA jrthompson114@gmail.com.
authors: Janelle R
authors: JR
authors: Thompson
mesh_terms: D001407:Bacillus / Q000145:classification* / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology; D002245:Carbon Dioxide / Q000378:metabolism* / Q000494:pharmacology; D057965:Carbon Sequestration; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D019015:Geologic Sediments / Q000382:microbiology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D002245:Carbon Dioxide