Vozchikova S.V.,
Lyakova A.O., Alferov S.V.
Tula State
University, Russia
The possibility of using
immobilized membrane fraction of bacteria Gluconobacter
oxydans as biocatalysts in Biofuel cell.
Biofuel cells (BFC) is a device that directly converts
chemical energy into electricity through the substrate biocatalytic oxidation
of organic or inorganic substances.The basis of the BFC is a biocatalyst -
individual enzymes and whole cells of microorganisms. Bacteria Gluconobacter oxydans have a unique
organization of the metabolic system, characterized by membrane localization of
dehydrogenases, which provides easy access of the substrate to the enzyme
active cites and allows the use of these microorganisms as a biocatalyst in the
BFC. Using the membrane fraction as biocatalyst so it can be an alternative of
enzymes application. It is more economically advantageous since the process of
obtaining a membrane fraction is an intermediate step in isolation of
individual enzymes, and therefore less expensive. In BFC biocatalyst may be
provided with a suspension of cells or immobilized biomaterial on the electrode
directly. Immobilization on the surface of the anode allows the reuse of the
biocatalyst is applied, in turn, increases the long term stability of the BFC,
and also promotes a more rapid and efficient transfer of electrons to the
electrode.
The goal of this work was to study the stability (long-term
and operational) of BFC model based on immobilized membrane fraction of
bacteria G. Oxydans.
Immobilization of membrane fraction G. oxydans in glutaraldehyde on the
surface of a graphite electrode (anode) was performed by mixing of 30 mg of a
membrane fraction with 5 µL of 25% glutaraldehyde and by coated graphite
electrode with resulting slurry (coating height 1 cm). Then, the electrode with
immobilized membrane fraction left for 30 min. in air and used for measurements.
Operating stability is one of the most important
characteristics of the electrode. It shows a resistance value generated by
adding potential of the same substrate concentration (10 mM glucose) for
carrying out a large number of successive measurements. To determine the
operational stability was conducted 10 consecutive measurements with bioanoda
adding 30 µL of 1M solution of glucose (concentration in the anode compartment
10 mmol/dm3).
It was established that the number of successive
measurements, by using the immobilized biocatalyst is not less than 10. Maximum
generation potential is carried out for 3-5 minutes.Relative standard deviation
was 3.6%.
Long-term stability
characterizes the stability of the
electrode for a prolonged period
of time. Long-term stability was determined by means of daily measurement (day 8)
the values of generated potential by adding 30 µL of glucose solution of
(concentration in the anode compartment 10 mmol/l). Between the measurements
the electrodes were stored in a buffer solution in the refrigerator. It was established
that the reduction of the generated potential by 50% was after 3 days application.
Thus, the use of immobilized membrane fraction of
bacteria G. Oxydans as biocatalyst in
BFC model is more efficient than the use of a membrane fraction in suspended
form. After studying the long-term operating stability and found that the
immobilized biocatalyst due to a stable operation of the electrode continues
for 5 days, encouraging consistency can be carried out for at least 10
measurements.
GRATITUDE
This work was supported by RFBR grant agreement ¹
13-03-97514/13 and Ministry of
Education and Science of Russian Federation (State Task project code 1764).