Metabolt: An in-situ instrument to characterize the metabolic activity of microbial soil ecosystems using electrochemical and gaseous signatures

Miracle Israel Nazarious*, María Paz Zorzano, Javier Martín-Torres

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Metabolt is a portable soil incubator to characterize the metabolic activity of microbial ecosystems in soils. It measures the electrical conductivity, the redox potential, and the concentration of certain metabolism-related gases in the headspace just above a given sample of regolith. In its current design, the overall weight of Metabolt, including the soils (250 g), is 1.9 kg with a maximum power consumption of 1.5 W. Metabolt has been designed to monitor the activity of the soil microbiome for Earth and space applications. In particular, it can be used to monitor the health of soils, the atmospheric-regolith fixation, and release of gaseous species such as N2, H2O, CO2, O2, N2O, NH3, etc., that affect the Earth climate and atmospheric chemistry. It may be used to detect and monitor life signatures in soils, treated or untreated, as well as in controlled environments like greenhouse facilities in space, laboratory research environments like anaerobic chambers, or simulating facilities with different atmospheres and pressures. To illustrate its operation, we tested the instrument with sub-arctic soil samples at Earth environmental conditions under three different conditions: (i) no treatment (unperturbed); (ii) sterilized soil: after heating at 125C for 35.4 h (thermal stress); (iii) stressed soil: after adding 25% CaCl2 brine (osmotic stress); with and without addition of 0.5% glucose solution (for control). All the samples showed some distinguishable metabolic response, however there was a time delay on its appearance which depends on the treatment applied to the samples: 80 h for thermal stress without glucose, 59 h with glucose; 36 h for osmotic stress with glucose and no significant reactivation in the pure water case. This instrument shows that, over time, there is a clear observable footprint of the electrochemical signatures in the redox profile which is complementary to the gaseous footprint of the metabolic activity through respiration.

Original languageEnglish
Article number4479
Number of pages18
JournalSensors
Volume20
Issue number16
DOIs
Publication statusPublished - 11 Aug 2020

Keywords

  • Astrobiology
  • Electrical conductivity
  • Gas monitoring
  • Greenhouses
  • Metabolt
  • Microbial metabolism
  • Planetary analogue research
  • Planetary exploration
  • Redox potential
  • Space
  • microbial metabolism
  • planetary exploration
  • gas monitoring
  • space
  • greenhouses
  • astrobiology
  • planetary analogue research
  • SCIENCE
  • BACTERIA
  • ENVIRONMENTS
  • ELECTRICAL-CONDUCTIVITY
  • redox potential
  • HABITABILITY
  • MICROORGANISMS
  • DOMINANCE
  • WATER-ACTIVITY
  • electrical conductivity

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