title: Diversity and interactions of microbial functional genes under differing environmental conditions: insights from a membrane bioreactor and an oxidation ditch.
abstract: The effect of environmental conditions on the diversity and interactions of microbial communities has caused tremendous interest in microbial ecology. Here, we found that with identical influents but differing operational parameters (mainly mixed liquor suspended solid (MLSS) concentrations, solid retention time (SRT) and dissolved oxygen (DO) concentrations), two full-scale municipal wastewater treatment systems applying oxidation ditch (OD) and membrane bioreactor (MBR) processes harbored a majority of shared genes (87.2%) but had different overall functional gene structures as revealed by two datasets of 12-day time-series generated by a functional gene array-GeoChip 4.2. Association networks of core carbon, nitrogen and phosphorus cycling genes in each system based on random matrix theory (RMT) showed different topological properties and the MBR nodes showed an indication of higher connectivity. MLSS and DO were shown to be effective in shaping functional gene structures of the systems by statistical analyses. Higher MLSS concentrations resulting in decreased resource availability of the MBR system were thought to promote positive interactions of important functional genes. Together, these findings show the differences of functional potentials of some bioprocesses caused by differing environmental conditions and suggest that higher stress of resource limitation increased positive gene interactions in the MBR system.
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, 100084, Beijing, P.R. China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xia
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, 100084, Beijing, P.R. China.
authors.forename: Man
authors.initials: M
authors.lastname: Hu
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, 100084, Beijing, P.R. China.
authors.forename: Xianghua
authors.initials: X
authors.lastname: Wen
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, 100084, Beijing, P.R. China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Wang
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, 100084, Beijing, P.R. China.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, 100084, Beijing, P.R. China.|Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, OK, USA.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D001673:Biodegradation, Environmental; D019149:Bioreactors; D002244:Carbon / Q000378:metabolism; D015870:Gene Expression; D005798:Genes, Bacterial; D005800:Genes, Fungal; D006801:Humans; D008567:Membranes, Artificial; D059013:Microbial Consortia / Q000235:genetics*; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000382:microbiology*
chemical_list: D002244:Carbon; D008567:Membranes, Artificial; D009584:Nitrogen; D010100:Oxygen; D010758:Phosphorus; D062065:Wastewater