Evaluation of microbial inocula for initiation of biological life support systems for wastewater processing on long term and deep space missions

A fundamental goal of ecological research is to better understand the relationship between structural diversity, functional diversity and ecosystem stability. Insight into the mechanisms that regulate microbial ecosystem function should provide important new information to improve system control for ecological, agricultural and biotechnological applications that depend on microbial processes. This is directly applicable to closed environmental systems employed by the National Aeronautics and Space Administration (NASA), since microbial inocula will likely be used to initiate any biological waste processing system used on long term space missions. To assure safe, reliable functioning of inoculated systems, it will be important to manage microbial populations within these systems to optimize the positive functions of inoculated communities.; This research focuses on the use of a model plant-based graywater waste processing system to evaluate the effect of species diversity on community phenotype and community invasibility. The principal hypothesis of this research is that a community of rhizosphere organisms, constructed using parameters described in this research, will be as effective as an undefined industrial activated sludge community in terms of its ability to: establish in the rhizosphere, persist over time, resist invasion, and degrade organic compounds. To address this hypothesis, a combination of PCR-based phylogenetic analysis and quantification, community level physiological profiling and microarray analysis was employed to evaluate the effect of microbial community structure on community dynamics, community stability and ecosystem processes.; Differences in species diversity corresponded to differences in phenotypic potential (surfactant degradation and CLPP) and differences in resistance to invasion. All of the communities were phenotypically diverse, however, only communities with higher species diversity were able to degrade surfactant and to resist invasion by a competitor. The constructed community was phenotypically diverse, and even degraded surfactant to a greater extent than any of other the other treatments. However, this community was invaded to a greater extent than any of the other communities, the invader persisted in the population, and one member of the community was completely displaced upon invasion. These results suggest that increased species diversity improved system performance by increasing community persistence, resistance to invasion and ability to degrade surfactant.