Electrochemistry of Oral Plaque Microbes: A New Insight into the Oral Peridontis Disease

Name     :  NARADASU DIVYA

Nationality :  INDIAN

Theme    :  Electron transportation study in oral
cavity/ plaque

Nowadays
number of people are suffering from oral diseases caused by microbes which
usually grow on our teeth resulted in formation of plaque on the bone or its
dissolution.

The bone
or teeth dissolution by microbial flora is stimulated by protons accumulation
in the plaque biofilm. The acidification is rapid and the supragingival pH
can reach around 4 within several minutes, which has been considered due to
the amassing of lactic acid with pK_a of 3.9 (Fig. 1). However,
recent microbial community analysis revealed that there are 1200 Ð 70000 kinds of microbial strains in the plaque biofilm,
indicating the microbial community is much more complex than previously
thought and thus lactate should be rapidly consumed as electron donor. Thus
the mechanism how microbial flora make acidic condition at the mineral
surface remained ambiguous.

We recently
found that one of the microbes in the plaque biofilm is capable of performing
Extracellular electron transport (EET) during their anaerobic respiration
process consuming lactate as a sole electron donor. Extracellular electron
transport is the mechanism in which microbes couple their metabolism with
electron transport process via the outer membrane-bound cytochrome c-type
cytochromes across the outer membrane from inside of cell.

Thus, EET by microbes adhered to the surface of gum or bone
possibly triggers proton accumulation in the biofilm by consuming lactic acid, acetic acid and formic acid that mutans
bacteria produce.

Biofilm stay in the depth of bone, which makes the
treatment of plaque difficult, and the microorganism found in plaque is known
to be predominant in formation of thick nanowires and secretes extracellular
polysaccharides to sustain the biofilm from previous studies.

With the
help of these studies, we may find out why protons are being accumulated
while electrons are being transferred and how microbes are changing their
redox environment to acidic condition and still surviving under acidic
stress. Thus, a way to suppress, remove the plaque, and kill the microbes by
altering their nature like changing or manipulating the redox environments
can be found.