Microbial Astronauts: Assembling Microbial Communities for Advanced Life Support Systems

Dynamac Inc., DYN-3, John F. Kennedy Space Center, FL 32899, USA.
Microbial Ecology (Impact Factor: 2.97). 03/2004; 47(2):137-49. DOI: 10.1007/s00248-003-1060-5
Source: PubMed


Extension of human habitation into space requires that humans carry with them many of the microorganisms with which they coexist on Earth. The ubiquity of microorganisms in close association with all living things and biogeochemical processes on Earth predicates that they must also play a critical role in maintaining the viability of human life in space. Even though bacterial populations exist as locally adapted ecotypes, the abundance of individuals in microbial species is so large that dispersal is unlikely to be limited by geographical barriers on Earth (i.e., for most environments "everything is everywhere" given enough time). This will not be true for microbial communities in space where local species richness will be relatively low because of sterilization protocols prior to launch and physical barriers between Earth and spacecraft after launch. Although community diversity will be sufficient to sustain ecosystem function at the onset, richness and evenness may decline over time such that biological systems either lose functional potential (e.g., bioreactors may fail to reduce BOD or nitrogen load) or become susceptible to invasion by human-associated microorganisms (pathogens) over time. Research at the John F. Kennedy Space Center has evaluated fundamental properties of microbial diversity and community assembly in prototype bioregenerative systems for NASA Advanced Life Support. Successional trends related to increased niche specialization, including an apparent increase in the proportion of nonculturable types of organisms, have been consistently observed. In addition, the stability of the microbial communities, as defined by their resistance to invasion by human-associated microorganisms, has been correlated to their diversity. Overall, these results reflect the significant challenges ahead for the assembly of stable, functional communities using gnotobiotic approaches, and the need to better define the basic biological principles that define ecosystem processes in the space environment.

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Available from: Jay L Garland, Mar 17, 2014
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    • "In rich communities it is more likely that at least one of the community members has an antagonistic activity against pathogenic invaders . The beneficial effect of a higher richness on pathogen invasion resistance was described by Roberts et al. (2004). It seemed that a lower diversity in the microbial rhizosphere community in dwarf wheat led to a higher susceptibility to invasion by Pseudomonas. "
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    • "Up to date diverse artificial ecosystems are elaborated (Tamponnet et al., 1993; Hirafuji et al., 2001; Godia et al., 2002; Allen et al., 2003; Tikhomirov et al., 2003; Sychev et al., 2003; Czupalla et al., 2004; Rodriguez et al., 2004), and both the models and experience to explore them could be used for life support on the Moon. Some of them anticipate use of microorganisms for purposively cultivating plants (Holland, 2000; Gros et al., 2003; Roberts et al., 2004). The aim of this study is theoretical substantiation of growing pioneer plants in a lunar base healthy and at low cost, and this is based partially on our first experimental results. "
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    • "Observations that the microbial world is hyperdiverse (Curtis et al. 2002; Roberts et al. 2004) and that microbial communities are characterized by functional redundancy (Edelman and Galley 2001; Roberts et al. 2004) lead to questions related to the distribution of microbial taxa across sites that are similar in their functional capabilities. For example, salt marshes contain a limited variety of plants that have a broad range of climatic conditions within which they flourish. "
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