Sulfide alters microbial functional potential in a methane and nitrogen cycling biofilm reactor |
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Authors: | Jeseth Delgado Vela Laura A Bristow Hannah K Marchant Nancy G Love Gregory J Dick |
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Institution: | 1. Department of Civil and Environmental Engineering, Howard University, Washington, DC, USA;2. Department of Biology, University of Southern Denmark, Odense, Denmark;3. Max Planck Institute for Marine Microbiology, Bremen, Germany;4. Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, MI, USA;5. Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA |
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Abstract: | Cross-feeding of metabolites between coexisting cells leads to complex and interconnected elemental cycling and microbial interactions. These relationships influence overall community function and can be altered by changes in substrate availability. Here, we used isotopic rate measurements and metagenomic sequencing to study how cross-feeding relationships changed in response to stepwise increases of sulfide concentrations in a membrane-aerated biofilm reactor that was fed with methane and ammonium. Results showed that sulfide: (i) decreased nitrite oxidation rates but increased ammonia oxidation rates; (ii) changed the denitrifying community and increased nitrous oxide production; and (iii) induced dissimilatory nitrite reduction to ammonium (DNRA). We infer that inhibition of nitrite oxidation resulted in higher nitrite availability for DNRA, anammox, and nitrite-dependent anaerobic methane oxidation. In other words, sulfide likely disrupted microbial cross-feeding between AOB and NOB and induced cross-feeding between AOB and nitrite reducing organisms. Furthermore, these cross-feeding relationships were spatially distributed between biofilm and planktonic phases of the reactor. These results indicate that using sulfide as an electron donor will promote N2O and ammonium production, which is generally not desirable in engineered systems. |
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