title: Microbial community of granules in expanded granular sludge bed reactor for simultaneous biological removal of sulfate, nitrate and lactate.
abstract: This study studied the cultivation of granules from an expanded granular sludge bed reactor that simultaneously transforms sulfates, nitrates, and oxygen to elementary sulfur, nitrogen gas, and carbon dioxides, respectively. The living cells accumulate at the granule outer layers, as revealed by the multicolor staining and confocal laser scanning microscope technique. The microbial community comprises sulfate-reducing bacteria (SRB, Desulfomicrobium sp.), heterotrophic (Pseudomonas aeruginosa and Sulfurospirillum sp.), and autotrophic denitrifiers (Sulfurovum sp. and Paracoccus denitrificans) whose population dynamics at different sulfate and nitrate loading rates are monitored with the single-strand conformation polymorphism and denaturing gradient gel electrophoresis technique. The Desulfomicrobium sp. presents one of the dominating strains following reactor startup. At high sulfate and nitrate loading rates, the heterotrophic denitrifiers overcompete autotrophic denitrifiers to reduce SRB activities. Conversely, suddenly reducing nitrate loading rates completely removes the heterotrophic denitrifier Sulfurospirillum sp. from the granules and activates the autotrophic denitrifiers. The physical fixation of different groups of functional strains in granules fine-tunes the strains' activities, and hence the reactor performance.
authors.affiliation: School of Municipal & Environmental Engineering, Harbin Institute of Technology, P. O. Box 2614, 202 Haihe Road, Harbin 150090, China.
authors.forename: Chuan
authors.initials: C
authors.lastname: Chen
authors.forename: Nanqi
authors.initials: N
authors.lastname: Ren
authors.forename: Aijie
authors.initials: A
authors.lastname: Wang
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Yu
authors.forename: Duu-Jong
authors.initials: DJ
authors.lastname: Lee
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D016172:DNA Fingerprinting; D019344:Lactic Acid / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D013431:Sulfates / Q000378:metabolism*; D014865:Waste Disposal, Fluid
chemical_list: D009566:Nitrates; D012722:Sewage; D013431:Sulfates; D019344:Lactic Acid