# Presentation: 107980

## Analytical Methods for Monitoring Functional and Genetic Diversity of Microbial Communities in the ARMS Bioreactor

- Julia A.L. Shimizu
- Controlled Biological Sciences Trainee
- 2004 Spaceflight and Life Sciences Training Program
- Colorado State University
- Fort Collins, CO   80523
- Michael S. Roberts
- Principal Investigator
- Dynamac Corporation
- Kennedy Space Center, FL   32899

## 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

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- Figure 1: Each ARMS reactor contains a bundle of silastic membranes designed to supply oxygen via bubble-less aeration  to attached microbial communities.

- Figure 2: Bioreactor schematic showing silastic membranes.

- bioreactor

- Silastic membrane

- Figure 3: 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

- Figure 3 Decreasing R2A concentration tends to decrease peak height and occurrence of asymptotic peaks

- Figure 4 Decreasing inoculum density tends to decrease asymptotic peak occurrence