Analytical Methods for Monitoring Functional and Genetic Diversity of Microbial Communities in the ARMS Bioreactor
Aerobic Rotational Membrane System (ARMS)
Bioregenerative life support system to treat urine, humidity condensate, and graywater for eventual reuse
• Utilizes natural metabolic processes (nitrification) of microbes to reduce ammonia-nitrogen and organic compounds
• Effectiveness of the bioreactor depends on the health of these microbial communities
Methods
Above: (Left) Each ARMS reactor contains a bundle of silastic membranes designed to supply oxygen via bubble-less aeration to attached microbial communities.
Above: (Middle) Bioreactor schematic showing silastic membranes.
Above: (Right) Laser scanning confocal microscope image of ammonia-oxidizing bacteria (green) and nitrite-oxidizing bacteria (red) in a nitrification bioreactor. Image courtesy of Dr. Michael Wagner, Munich Institute of Technology.
Functional & Genetic Diversity: Objectives, Results, Conclusions
• Objective 1: Compare the functional potential and genetic diversity of attached communities (biofilm) to free-floating communities (within the effluent) within the ARMS bioreactors
Function potential assessed via BD Oxygen Biosensor System (BD OBS)
Genetic diversity assessed via Terminal Restriction Fragment Length Polymorphism (T-RFLP)
• Communities responded best to urine salts without organic components, and urine salts with organic components (hippuric acid, tyrosine, and creatinine)
Biofilm communities responded differently than the communities that were free-floating
Tendency for biofilm communities to respond more quickly than communities that were flocculent
• One sample was analyzed using T-RFLP
Two replicates of the sample were run and found to share >82% similarity (based on the Jaccard Similarity Coefficient)
• T-RFLP is an effective means of determining the genetic diversity of a community
Attached and free-floating communities respond differently to the same resources due to variations in community makeup
Redefining BD Oxygen Biosensor Plate Protocols: Objectives, Results, Conclusions
• Objective 2: Determine the effects of resource concentration and inoculum density on the response of the ARMS communities to redefine BD OBS protocol
BD OBS is used to evaluate the functional potential of microbial communities
• Decreasing concentration of the R2A media and decreasing inoculum concentration tends to increase the occurrence of simple peaks (rapid, short duration) for easy analysis
This is due to a decrease in carbon source for community response.
Above: Decreasing R2A concentration tends to decrease peak height and occurrence of asymptotic peaks.
Above: Decreasing inoculum density tends to decrease asymptotic peak occurrence.
Author: Julia A.L. Shimizu, Controlled Biological Sciences Trainee
2004 Spaceflight and Life Sciences Training Program
Colorado State University, Fort Collins, CO 80523
Principal Investigator: Michael S. Roberts, Dynamac Corporation
Kennedy Space Center, Florida
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