Interactions between perchlorate and nitrate reductions in the biofilm of a hydrogen-based membrane biofilm reactor.
We studied the microbial functional and structural interactions between nitrate (NO(3)(-)) and perchlorate (ClO(4)(-)) reductions in the hydrogen (H(2))-based membrane biofilm reactor (MBfR). When H(2) was not limiting, ClO(4)(-) and NO(3)(-) reductions were complete, and the MBfR's biofilm was composed mainly of bacteria from the ε- and β-proteobacteria classes, with autotrophic genera Sulfuricurvum, Hydrogenophaga, and Dechloromonas dominating the biofilm. Based on functional-gene and pyrosequencing assays, Dechloromonas played the most important role in ClO(4)(-) reduction, while Sulfuricurvum and Hydrogenophaga were responsible for NO(3)(-) reduction. When H(2) delivery was insufficient to completely reduce both electron acceptors, NO(3)(-) reduction out-competed ClO(4)(-) reduction for electrons from H(2), and mixotrophs become important in the MBfR biofilm. β-Proteobacteria became the dominant class, and Azonexus replaced Sulfuricurvum as a main genus. The changes suggest that facultative, NO(3)(-)-reducing bacteria had advantages over strict autotrophs when H(2) was limiting, because organic microbial products became important electron donors when H(2) was severely limiting.
Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, Arizona 85287-5701, United States. hzhao21@asu.edu
He-Ping
HP
Zhao
Steve
S
Van Ginkel
Youneng
Y
Tang
Dae-Wook
DW
Kang
Bruce
B
Rittmann
Rosa
R
Krajmalnik-Brown
D001419:Bacteria / Q000378:metabolism; D020562:Betaproteobacteria / Q000378:metabolism; D018441:Biofilms; D019149:Bioreactors; D008567:Membranes, Artificial; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism*; D010472:Perchlorates / Q000737:chemistry / Q000378:metabolism*
D008567:Membranes, Artificial; D009566:Nitrates; D010472:Perchlorates; C494474:perchlorate