Response of soybean rhizosphere communities to human hygiene water addition as determined by community level physiological profiling (CLPP) and terminal restriction fragment length polymorphism (TRFLP) analysis

In this report, we describe an experiment conducted at Kennedy Space Center in the biomass production chamber (BPC) using soybean plants for purificat ion and processing of human hygiene water. Specifically, we tested whether it was possible to detect changes in the root-associated bacterial assembla ge of the plants and ultimately to identify the specific microorganism(s) w hich differed when plants were exposed to hygiene water and other hydroponi c media. Plants were grown in hydroponics media corresponding to four diffe rent treatments: control (Hoagland's solution), artificial gray water (Hoag land's+surfactant), filtered gray water collected from human subjects on si te, and unfiltered gray water. Differences in rhizosphere microbial populat ions in all experimental treatments were observed when compared to the cont rol treatment using both community level physiological profiles (BIOLOG) an d molecular fingerprinting of 16S rRNA genes by terminal restriction fragme nt length polymorphism analysis (TRFLP). Furthermore, screening of a clonal library of 16S rRNA genes by TRFLP yielded nearly full length SSU genes as sociated with the various treatments. Most 16S rRNA genes were affiliated w ith the Klebsiella. Pseudomonas, Variovorax, Burkholderia, Bordetella and I sosphaera groups. This molecular approach demonstrated the ability to rapid ly detect and identify microorganisms unique to experimental treatments and provides a means to fingerprint microbial communities in the biosystems be ing developed at NASA for optimizing advanced life support operations. (C) 2000 Federation of European Micro biological Societies. Published by Elsevi er Science B.V. All rights reserved.