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.

Microbial Degradation of Hydrocarbons—Basic Principles for Bioremediation: A Review

“…Contrary to common beliefs, the solubility of oxygen in most hydrocarbon mixtures is higher by even one order of magnitude compared to water (e.g., 15.7 mM in hexane and 8.7 mM in toluene compared to 1.3 mM in water [11]). Hence, the biofilm growing on the oil-water interface in oil tanks consists mostly of aerobic and facultative aerobic species that deplete the oxygen and nutrients, which may result in a progressive alteration of the bacterial community structure [27][28][29]. This results in strictly anaerobic conditions at the bottom of the cylinders.…”

Comparison of Oxidation Kinetics of Nitrite-Oxidizing Bacteria: Nitrite Availability as a Key Factor in Niche Differentiation

“…An open question is the relevance of the new candidate genus Nitrotoga (24) for the treatment of wastewaters. These NOB were detected primarily in soils (24) but also occur in cave biofilm (25), freshwater (26), and activated sludge (27)(28)(29).Here we present a broad comparison of directly measured oxidation kinetics of nonmarine NOB by microsensor measurements. In addition to Nitrobacter, the study includes pure cultures of lineage I and II Nitrospira from freshwater and activated sludge and the first analysis of a highly enriched Nitrotoga culture from permafrost soil.…”

“…An open question is the relevance of the new candidate genus Nitrotoga (24) for the treatment of wastewaters. These NOB were detected primarily in soils (24) but also occur in cave biofilm (25), freshwater (26), and activated sludge (27)(28)(29).…”

Aerobic and oxygen-limited naphthalene-amended enrichments induced the dominance of Pseudomonas spp. from a groundwater bacterial biofilm

“…For phylogenetic T-RFLP analysis, 16S rRNA genes from the initial biofilm and from the enrichments DNA were PCR amplified by using VIC fluorescently labelled 27F and nonlabelled 1492R primers. Reagent concentrations and PCR conditions were the same as described earlier (Benedek et al 2014). The obtained PCR products were digested with 1 U AluI (AG↓CT) restriction endonuclease (Fermentas, Lithuania) for 1.5 h at 37°C.…”