|Cook, Kimberly - Kim|
Submitted to: Microbial Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/14/2005
Publication Date: 10/31/2007
Citation: Cook, K.L., Garland, J.L., Layton, A.C., Dionisi, H.M., Levine, L.F., Sayler, G.S. 2007. Effect of microbial species richness on community stability and community function in a model plant-based wastewater processing system. Microbial Ecology. 52:725-737. Interpretive Summary: The relationship between microbial species diversity and ecosystem function is of great interest in microbial ecology. Insight into the interation between these factors may make it posible to better predict system function, thus improving process control for ecological and biotechnological applications. In this study, the function and stability of microbial communities of different diversities were evaluated following inoculation into a plant-based graywater waste processing system. The microbial inocula were from a constructed community of culturable plant root zone microorganisms and gradient of communities derived from industrial wastewater treatment plant (WWTP) activated sludge. A WWTP community with high species diversity was able to resist invasion by an outside organism and degrade waste products added to the system. The community of cultrable plant root zone microoragnisms was very suscepitable to invasion, but contained organisms capable of degrading added waste products (surfactants). Results from these studies suggest that community function and community stability are influenced both by the structural composition of the community and by the overall diversity within the community.
Technical Abstract: Microorganisms will be an integral part of biologically based waste processing systems (WPS) used for water purification or nutrient recycling on long-term space missions planned by the National Aeronautics and Space Administration (NASA). In this study, the function and stability of microbial inocula of different diversities were evaluated following inoculation into plant-based graywater WPS. The microbial inocula were from a contructed community of culturable plant rhizosphere microorganisms and a complexity gradient (CG) of communities derived from industrial wastewater treatment plant (WWTP) activated sludge. Community stability and community function were defined in these studies as the ability of the community to resist invasion by a competitor (Pseudomonas fluorescens 5RL) and the ability to degrade surfactant, respectively. Carbon source utilization was evaluated by measuring surfactant degradation and through Biolog and BD oxygen biosensor community level physiological profiling(CLPP). Community profiles were obtained from a 16S-23S rDNA intergenic spacer region (ISR)array. A WWTP derived community with the greatest species richness (CGI) was the least susceptible to invasion and was able to degrade surfactant to a greater extent than the other Complexity Gradient communities. All communities (including a community of contaminant species consisting of three bacterial types) resisted invasion by a competitor to a greater extent than the plant rhizosphere isolate constructed community. However, the constructed community degraded surfactant to a greater extent than any of the other communities and utilized the same number of carbon sources as many of the other communities (CG2,CG3, CG4, and the propitious community). These results demonstrate that communitys function (carbon source utilization) and community stability (resistance to invasion) are a function of the structural composition of the community irrespective of species richness or functional richness.