title: Analysis of biofilm bacterial communities responsible for carbon removal through a reactor cascade treating wastewater.
abstract: In this study molecular microbiological and multivariate statistical analyses were carried out to determine the structure and dynamics of bacterial communities through a biofilm based, pilot-scale wastewater treatment cascade system comprised of eight reactors. Results indicated a vertical as well as horizontal differentiation of biofilm bacterial communities within individual reactors and through the reactor series, respectively. The richness of biofilm samples taken from dissolved oxygen rich sections of reactors were relatively lower than of samples taken from less oxygenized sections (one-way ANOVA P = 0.07). The Euclidean distance based one-way ANOSIM pointed out that in bacteriological point of view: (1) no statistically significant difference could be observed among the first five reactors (P ≥ 0.1); (2) the first seven reactors differed significantly from the last reactor, (P ≤ 0.03); (3) reactors 1 and 2 differed significantly from reactors 6 and 7 (P ≈ 0.02) and (4) reactor 3 from reactor 7 (P ≈ 0.03). 16S rRNA gene cloning revealed that through the cascade system the initially dominant heterotrophic bacteria (Acinetobacter, Acidovorax, Parabacteroides, Thauera, Desulfobacterium and Desulfomicrobium) were gradually replaced or supplemented by autotrophic nitrifying bacteria (Nitrosomonas, 'Candidatus Nitrotoga' and Nitrospira). Our results indicate that the vertical alteration of bacterial community structure within a particular reactor was driven by the alteration of dissolved oxygen concentration, while the horizontal alteration of bacterial community structure through the cascade system was driven mainly by the gradually decreasing dissolved organic matter content and increasing dissolved oxygen concentration.
authors.affiliation: Regional University Center of Excellence in Environmental Industry, Szent István University, Páter K. u. 1, 2100, Gödöllő, Hungary.
authors.forename: Tibor
authors.initials: T
authors.lastname: Benedek
authors.forename: András
authors.initials: A
authors.lastname: Táncsics
authors.forename: Nikolett
authors.initials: N
authors.lastname: Szilágyi
authors.forename: Imre
authors.initials: I
authors.lastname: Tóth
authors.forename: Milán
authors.initials: M
authors.lastname: Farkas
authors.forename: Sándor
authors.initials: S
authors.lastname: Szoboszlay
authors.forename: Csilla
authors.initials: C
authors.lastname: Krifaton
authors.forename: Mátyás
authors.initials: M
authors.lastname: Hartman
authors.forename: Balázs
authors.initials: B
authors.lastname: Kriszt
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000302:isolation & purification / Q000378:metabolism; D018407:Bacterial Physiological Phenomena; D018441:Biofilms / Q000254:growth & development*; D019149:Bioreactors / Q000382:microbiology; D058448:Biota; D002244:Carbon / Q000378:metabolism*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D062065:Wastewater / Q000382:microbiology*; D018508:Water Purification
chemical_list: D002244:Carbon; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D062065:Wastewater