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FINGERPRINTING OF BACTERIA BEFORE AND AFTER TREATMENT IN A PRESSURIZED CARBON REMOVAL BIOREACTOR.  Nitya Nair¹, Majda Nashashibi-Rabah², Christos Christodoulatos², Lee Kerkhof¹. ¹Institute of Marine and Coastal Sciences Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901-8521 and ²Stevens Inst. of Technology, Center for Environmental Engineering, Castle Point on Hudson, Hoboken, NJ 07030.

     This study was conducted to assess the differences in microbial populations between the feedstock of a gray water treatment reactor and the effluent for replicate reactors.  Microbial biomass from samples of both influent and effluent were collected by centrifugation.  DNA was extracted and microbial populations were characterized by PCR amplification of 16S rRNA (total community) and nifH (nitrogen fixing) target genes.  Microbial communities were fingerprinted using terminal restriction length fragment polymorphism analysis (TRFLP).  The feed stock was found to contain 16 major 16S rRNA peaks (90%of total TRFLP area) while duplicate reactors effluent contained 15 and 18 peaks respectively.  Nitrogen fixers accounted for 2 major nifH peaks in the feed with 2 and 4 peaks in the reactor effluents.  Four 16S peaks in the feed (87,234,405, and 437 bp) was not found in either reactor’s effluent. New 16S peaks in reactor 1 were 208, 213, 217, and 250.  However, these peaks were not seen in reactor 2.  The nifH profiles were much simpler with a 227, 321, and 361 bp TRFLP peaks present in the feed, and both reactors.  Again, reactor 2 was different with a novel, major 218 bp nifH peak in the effluent not present in either the feed or reactor 1.  These results were not expected given the reactors were installed at the same time and given the same gray water feed stock.  Work is underway to assess microbial populations within each reactor and determine if differences in microbial communities correlate with reactor performance.  In the future, this information may help to improve reactor design or start up procedures.

     (This work was supported by NASA grant 00-HEDS-01-043 in the Advanced Life Support Program)