TITLE:
Microbial Biofilms Formed in a Laboratory-Scale Anammox Bioreactor with Flexible Brush Carrier
AUTHORS:
E. A. Botchkova, Yu. V. Litti, B. B. Kuznetsov, A. N. Nozhevnikova
KEYWORDS:
Anammox; Anammox-Bacteria; Biofilm; Microbial Community; Chloroflexi
JOURNAL NAME:
Journal of Biomaterials and Nanobiotechnology,
Vol.5 No.2,
March
31,
2014
ABSTRACT: This study is focused on investigation of
biofilms formed in an anaerobic laboratory-scale bioreactor fed with medium for
anammox bacteria oxidizing ammonia with nitrite. The mixed culture of anammox
bacteria was enriched from the microbial community that sampled from the
activated sludge of a denitrifying reactor at a wastewater treatment station located
in the Sochi region, Russia. This community forms biofilms on the surface of
the flexible polymer brush carriers, which are used for biomass immobilization
in both laboratory and full-scale bioreactors. Anammox bacteria were
discovered in the activated sludge community. The anammox community was
enriched by incubation in an up-flow laboratory-scale anaerobic bioreactor with
a flexible brush carrier. In the course of ~3 years, the loading rate of
nitrogen substrates (ammonium and nitrite) increased from 100 to 5000 mg N L-1 day-1. The concentration of the substrates in the upper part of the
reactor was 40 times less than in the influent. The pH values were 7.5 at the
bottom and up to 9 in the upper part up of the reactor. Biofilms of two types
developed in the reactor. Bunches of irregular spherical granules formed on the
carrier filaments, while films of irregular thickness containing submerged
spherical granules were formed on the walls of reactor. The anammox population
was found to consist of at least three active species: a new strain of Candidatus “Jettenia asiatica” named “strain ecos” and two species of the genus Candidatus “Brocadia”. Other
types of bacteria found in the community, including members of phylum Chloroflexi, were presumably involved in
biofilm spatial organization.