Choice of Microbial System for In-Situ Resource Utilization on Mars

Abstract

Various microbial systems have been explored for their applicability to in-situ resource utilisation (ISRU) on Mars and suitability to leverage Martian resources and convert them into useful chemical products. Considering only fully bio-based solutions, two approaches can be distinguished, which comes down to the form of carbon that is being utilized: (a) the deployment of specialised species that can directly convert inorganic carbon (atmospheric CO2) into a target compound or (b) a two-step process that relies on independent fixation of carbon and the subsequent conversion of biomass and/or complex substrates into a target compound. Due to the great variety of microbial metabolism, especially in conjunction with chemical support-processes, a definite classification is often difficult. This can be expanded to the forms of nitrogen and energy that are available as input for a biomanufacturing platform. To provide a perspective on microbial cell factories that may be suitable for Space Systems Bioengineering, a high-level comparison of different approaches is conducted, specifically regarding advantages that may help to extend an early human foothold on the red planet.

The smallest space miners: principles of space biomining

“…We will try to address these questions, to the best of our knowledge, in this section. Answering these questions can be complex, as it involves an interdisciplinary knowledge of the space conditions present on the planetary body we want to mine, the type of rocks and mineral compositions available (including their intrinsic leachability and toxicity), the engineering technologies and biotechnologies required, in-space operational approach (a thorough discussion on the requirements for life support systems and ISRU for space exploration, although focused on cyanobacteria-based structures, has been reported in Keller et al 2021 ), and the appropriate microorganism(s) and its metabolism(s) (Averesch 2021 ). The situation becomes even more complicated when discussing asteroid biomining, given that the mined resources would likely not be used in situ, therefore requiring additional transport to the location of utilization (see Sect.…”

“…Unless the parent material contains high concentrations of salts (e.g., NaCl) there is no a priori reason why any of the materials discussed above should result in unsuitable water activities. The potential toxicity caused by ions (e.g., heavy metals) will depend on the material and the organisms used, but clearly this must be considered for any given combination of minerals and biomining organisms proposed (Averesch 2021 ).…”

“…The use of chemolithotroph microorganisms in space biomining has two main advantages: first, the mechanisms have been widely characterized and second, they do not require the presence of organic compounds to grow (Averesch 2021 ). Growth, interaction and metal extraction from space rocks/regolith or analogues using chemolithotroph microorganisms have been demonstrated (González-Toril et al 2005 ; Gronstal et al 2009 ; Kölbl et al 2017 ; Tait et al 2017 ; Milojevic et al 2021 ).…”

Towards a Biomanufactory on Mars

“…Supplying O 2 safely without risking explosive gas mixtures, or wasting the precious resource, is again a question of reactor design and operation. Certain purple non-sulfur alphaproteobacteria (e.g., Rhodospirillum rubrum (Brandl et al, 1989;Heinrich et al, 2016) and Rhodopseudomonas palustris (Doud et al, 2017;Touloupakis et al, 2021)) also feature remarkable substrate flexibility and can produce PHAs (Averesch, 2021).…”

Space Bioprocess Engineering on the Horizon

“…Feedstock, loop-closure, environmental parameters and product needs will constrain the minimal set of organisms to develop and test for growth rate, optimal cultivation, robustness and resilience to space conditions and shelf-life, safety and genetic tractability, product yield, titer and rate, feedstock utilization and waste streams 24 . Once suitable chassis organisms have been evaluated and selected, the DBTL cycle can integrate staged co-design of the optimal process hardware (e.g.…”