1 research outputs found
Involvement in Denitrification is Beneficial to the Biofilm Lifestyle of <i>Comamonas testosteroni</i>: A Mechanistic Study and Its Environmental Implications
Comamonas is one of the most abundant
microorganisms in biofilm communities driving wastewater treatment.
Little has been known about the role of this group of organisms and
their biofilm mode of life. In this study, using Comamonas
testosteroni as a model organism, we demonstrated
the involvement of Comamonas biofilms
in denitrification under bulk aerobic conditions and elucidated the
influence of nitrate respiration on its biofilm lifestyle. Our results
showed that C. testosteroni could use
nitrate as the sole electron acceptor for anaerobic growth. Under
bulk aerobic condition, biofilms of C. testosteroni were capable of reducing nitrate, and intriguingly, nitrate reduction
significantly enhanced viability of the biofilm-cells and reduced
cell detachment from the biofilms. Nitrate respiration was further
shown to play an essential role in maintaining high cell viability
in the biofilms. RNA-seq analysis, quantitative polymerase chain reaction,
and liquid chromatography–mass spectrometry revealed a higher
level of bisÂ(3′-5′)-cyclic dimeric guanosine monophosphate
(c-di-GMP) in cells respiring on nitrate than those grown aerobically
(1.3 × 10<sup>–4</sup> fmol/cell vs 7.9 × 10<sup>–6</sup> fmol/cell; <i>P</i> < 0.01). C-di-GMP
is one universal signaling molecule that regulates the biofilm mode
of life, and a higher c-di-GMP concentration reduces cell detachment
from biofilms. Taking these factors together, this study reveals that
nitrate reduction occurs in mature biofilms of C. testosteroni under bulk aerobic conditions, and the respiratory reduction of
nitrate is beneficial to the biofilm lifestyle by providing more metabolic
energy to maintain high viability and a higher level of c-di-GMP to
reduce cell detachment