Themes

The research themes of the Mogul laboratory include the biochemistry of microorganisms isolated from spacecraft assembly facilities, the development of simple chemical and biochemical assays for microbial ecology, and Venus planetary science and astrobiology.

The laboratory projects in my lab are structured around the work of undergraduate and Master’s level students and integrated into the academic structure of the University through research and thesis-based courses for Chemistry and Biochemistry majors (CHM 4000, 4610, & 4620), Biological Sciences majors (BIO 4000, 4610, & 4620), volunteer students (all majors, CHM 4000), and Master’s levels students with Chemistry, Biochemistry, or Biology backgrounds.

 

Brief summaries of the ongoing projects are provided below.

• Venus planetary science and astrobiology: Considerations for past, present, and future habitability.

• Planetary Protection: Biochemical survival mechanisms of spacecraft-associated microorganisms.

• Chemical Biology: Development of molecular and biochemical assays for microbial ecology.

 

Venus Planetary Science and Astrobiology

In this work, we are re-evaluating physicochemical data pertaining to Venus' atmosphere to better estimate the potential for microbial habitability in the past on Venus' surface and present or future within Venus' clouds. 

 

In Mogul et al., Icarus 2023, we developed an analytical model for archived mass spectral data obtained by the Pioneer Venus project in 1978 and extracted the first and most complete altitude profile, to date, for CO₂ in units of density (kg m^-3) between the altitudes of ~1-55 km. Our analytical model for the mass spectra will enable future studies into vertical structure of Venus' atmosphere.

 

In Mogul et al., Geophys. Res. Lett. 2021, we re-analyzed archived mass spectral data obtained by the Pioneer Venus project in 1978 and extracted evidence of redox disequilibria in the clouds.  Our work yielded signs of phosphine, hydrogen sulfide, nitrous acid, nitric acid, carbon monoxide, hydrochloric acid, hydrogen cyanide, ethane, and potentially ammonia, chlorous acid, and tentative PxOy species.

 

In Mogul et al., Astrobiology 2021, we showed that calculated solar irradiances across Venus’ clouds, as well as thermal radiances from the surface, support the potential for day-to-night Earth-like phototrophy.  We also showed that Venus' spectra are potentially consistent with the aerosols in clouds being composed of partly neutralized sulfuric acid. Such conditions would favor a microbial habitable zone.

 

In Limaye et al., Astrobiology 2018, we showed that Venus' global spectra share similarities to Earth biomolecules and microorganisms, and obtained estimates of theoretical maximum biomass in the clouds using Earth's aerobiome as an example.

 

 

Survival of extremotolerant Acinetobacter isolated from NASA spacecraft and spacecraft assembly facilities.

This student-led effort focuses on the survival features of differing strains of Acinetobacter isolated from the cleanroom facilities where NASA spacecraft are assembled.  Specifically, we are working on isolates obtained from the surface of the pre-flight Mars Odyssey orbiter and the floor of the assembly facility for the Mars Phoenix lander. The Acinetobacter are Gram-negative and non-spore forming bacteria broadly associated with water, soil, and clinical environments.  Molecular genetic and cultivation studies indicate that the Acinetobacter are among the most abundant microorganisms in NASA and ESA assembly facilities, which are oligotrophic and low humidity cleanroom environments. 

Accordingly, we are studying the survival mechanisms and extremotolerantce of the spacecraft-associated Acinetobacter.  In 2023 (Miller et al., Front. Microbiol. 2023), we showed that cultures of the spacecraft-associated Acinetobacter tolerate and degrade Kleenol-30, a floor detergent used in NASA cleanrooms.  We showed that cultivation with Kleenol 30 elicits strain specific changes in the metabolome, cellular growth kinetics, and survival probabilities.  Together these results indicate that a floor isolate shows higher overall tolerances to Kleenol 30, when compared to a spacecraft surface isolate.  The spacecraft-associated Acinetobacter, therefore, may show tolerance to the floor cleansing conditions.

In 2018 (Mogul et al. Astrobiology, 2018), we showed that the spacecraft-associated Acinetobacter grow on ethanol as a sole carbon source under low-osmolarity conditions. We also showed that extracts of the 50v1 strain could oxidize 2-propanol (isopropyl alcohol, IPA) under NAD⁺-dependent conditions. These combined results suggest that alcohol-based cleaning agents could potentialluy be used as carbon and/or energy sources by the microorganisms within the NASA cleanrooms, such as the Acinetobacter.

Our biochemical work suggests that the spacecraft-associated Acinetobacter possess adaptations at the biochemical level that confer resistance towards oxidation, desiccation, and ultraviolet radiation exposure.  We recently purified an alkali-tolerant catalase enzyme from A. gyllenbergii 2P01AA (Mars Phoenix) (Muster et al., Astrobiology 2015), which possesses the perhaps the highest extremotolerance towards hydrogen peroxide among Gram-negative and non-spore forming bacteria.  In fact, our studies show that catalase activities are quite high in all tested spacecraft-associated Acinetobacter (Derecho et al., Astrobiology 2014). 

Additionally, our proteomic studies on A. gyllenbergii 2P01AA and A. radioresistens 50v1 (McCoy et al., Astrobiology 2012), which is also extremotolerant towards hydrogen peroxide, indicate that the oxidative extremotolerance is related to the enzyme-based degradation of peroxides (catalase and alkyl hydroperoxide reductase), energy/redox management (ATP synthase, alcohol dehydrogenase, and dihydrolipoamide dehydrogenase), protein synthesis/folding (EF-G, EF-Ts, peptidyl-tRNA hydrolase, and DnaK), membrane functions (OmpA-like protein and ABC transporter–related protein), and nucleotide metabolism (HIT family hydrolase). 

These findings provide key biochemical insights into the physiology of spacecraft-associated microorganisms. Our results suggest that the cleansing conditions used during spacecraft assembly are selective pressures. In turn, we suggest that the persistent cleanroom microbiome is potentially sustained by tolerance or metabolism of the cleaning reagents.  Such tolerances are likely important considerations for lower bioburden planetary missions, such as orbiter missions to Europa (Planetary Protection Category III), life detection missions to Mars (Planetary Protection Category IVb) or Europa (Planetary Protection Category, and investigations of Mars Special Regions (Planetary Protection Category IVc).

This research is based upon the work of undergraduate and Master’s level students and includes enzymology, proteomics, metabolomic, spectroscopic, and microbiology methods.  This work has been supported by the Planetary Protection element of NASA ROSES and the NASA Astrobiology Institute-Minority Institutional Research Support program.

American Society for Microbiology, May 2007

  

 

Life at the Extreme: Tools for Microbial Ecology

In this project, our student-powered team is developing molecular and biochemical tools to advance studies of microbial samples from extreme environments.

 

Simple kinetics and assay for soil microbial catalases.

In Chabot et al. Anal. Biochem. 2020, we developed, demonstrated, and applied a new kinetic model for microbial catalases using a simple, cost-effective, and field-amenable assay.  Our results suggest that microbial communities from biological soil crusts, high elevation soils, and permafrost experience substantial degrees of native oxidative stresses, and accordingly exhibit high catalase activities and abundances per 16S rRNA gene copy number.

 

Quantifying bacterial spores in ancient permafrost.

Methods development for organic-rich soils.

In Lalla et al. Anal. Biochem. 2020, we developed a simple and cost-effective method for using Tb(EDTA) to quantify bacterial spores in ancient permafrost.  Using a tandem filtration system and time-resolved lanthanide luminescence, we used Tb(EDTA) to measure an increase in spore abundance across a permafrost chronosequence.

Impact of terbium chelate structure.

In Barnes, et al., (J. Inorg. Biochem. 2011), we demonstrated the detection of Bacillus spores using the luminescent and cost-effective reagent of Tb(EDTA). We showed that the inclusion of hexadentate chelators, such as EDTA and DO2A, enhance reagent stability in complex mixtures and that (under un-optimized conditions) a gamma-resistant Bacillus spore could be detected at ~10⁴ cfu/mL.

 

Molecular and biochemical characterization of biological soil crusts.

The NASA/CSU Spaceward Bound program is an astrobiology field learning experience that functionally integrates pre- and in-service K12 STEM teachers into the scientific study of the Mojave desert.  I served as Director for this program, and during the expeditions across 2009-2016, students from the CSU, along with scientists from both the CSU and NASA, converged in the Mojave desert and combined their efforts towards the genetic, biochemical, and geochemical study of biological soil crusts, which are symbiotic microbial communities that assist in the nutrient and water cycling in arid lands.

Descriptions of the 2009, 2010, 2011, 2012, 2014, 2015, and 2016 expeditions can be found at the program website, which is www.spacewardbound.org.

In 2017, the students of several Spaceward Bound programs helped prepare a peer-reviewed manuscipt which was published in Frontiers in Microbiology. 

In Mogul et al. Front. Microbiol. 2017, we expanded upon the biogeography of biological soil crusts (BSCs) and provided molecular insights into the microbial community and biochemical dynamics along the vertical BSC column structure, and across a transect of increasing BSC surface coverage in the central Mojave Desert, CA, United States. Next generation sequencing revealed that the bacterial community profile is distinct among BSCs in the southwestern United States.  Our studies also suggest that BSCs from regions of differing surface coverage represent early successional stages, which exhibit increasing bacterial diversity, metabolic activities, and capacity to restructure the soil. The total results suggest that BSC successional maturation and colonization across the transect are inhibited by metals/metalloids such as B, Ca, Ti, Mn, Co, Ni, Mo, and Pb

 Mogul et al. Front. Microbiol. 2017

 

NASA planetary protection policy development and implementation.

My policy-related work in Planetary Protection centers upon the review of regulations designed to minimize the contamination of extraterrestrial environments, such as Mars and Europa, that may result from spacecraft exploration. In order to ensure the scientific integrity of life-detection missions (e.g., to avoid detection of false positives), a specific set of bioburden limits and cleaning procedures have been defined at both the international and Federal levels. Currently, I am re-drafting the Mars-related policy language in the NASA Procedural Requirements document, NPR 8020.12D, which is the primary Federal document that describes the NASA planetary protection guidelines for robotic missions. In parallel, I am conducting a comparative analysis of the bioburden regulatory limits (i.e., number of total allowed spores, maximum allowed surface density of spores, and probabilities of contamination) using both past and current policies from NASA, the European Space Agency (ESA), and the Committee on Space Research (COSPAR). This work was  supported through the NASA Research Opportunities in Space and Earth Sciences grants program.