INTRODUTION
Bacteria able to transfer electrons to metals are key agents in
biogeochemical metal cycling,
subsurface bioremediation, and corrosion processes. More recently, these
bacteria have gained attention as the transfer of electrons from the cell
surface to conductive materials can be used in multiple applications Enrico
Marsili 2008. The integration of biomolecules with electronic elements
to yield functional devices attracts substantial research efforts because of
the basic fundamental scientific questions and the potential practical
applications of the systems. The research field gained the buzzword
”bioelectronics” aimed at highlighting that the world of electronics could be
combined with biology and biotechnology Willner & Hoffmann, 2002. MFCs are
devices that exploit microbial catabolic activities to generate electricity
from a variety of materials, including complex organic waste and renewable
biomass. In MFCs, microbes utilize organic compounds as energy and carbon
sources. In order to generate energy for growth, organics are decomposed, and
chemical energy is released (i.e., fermentation). In addition, high-energy
electrons released from organics are transferred to oxidized chemicals (i.e.,
electron acceptors, such as molecular oxygen) to conserve electrochemical
energy (i.e., respiration). In microbial cells, electrons released from
organics are initially accepted by intercellular electron-shuttling compounds
(e.g., nicotinamide adenine dinucleotide NAD), and subsequently transferred
to electron acceptors via respiratory electron-transport chains. If a mechanism
is present by which electrons released from organics can be transferred from
any step in the intercellular electron-transfer pathway to an extracellular
electrode (i.e., anode), then microbial oxidation of organics can be coupled to
electricity It has been suggested that MFCs have many possible future
applications; these include water treatments coupled to energy recoveries,
portable fuel cells, biosensors, and in-situ energy sources. Among them, the
first one, waste treatments, is considered to be the most promising, and MFCs
may be able to work as energy- and cost-saving options for waste treatments (Watanabe
2008).
The MFC technology has however not yet been applied to practical waste
treatments. This is primarily because it is an emerging technology and more
time is required for technical maturation generation (i.e., an MFC).Recent
studies have identified that there exist bacteria that can use self-sustaining
extracellular electron transfer mechanisms to respire MFC anodes (Lovley 2008;
Watanabe et al. 2009). Some bacteria excrete water-soluble electron-shuttling
compounds that are reduced by bacterial cells and oxidized by transferring electrons
to MFC anodes (Watanabe et al. 2009). Other bacteria use secreted and/or
cell-surface electron-transporting proteins (e.g., cytochromes) for the
electron transfer toward MFC anodes (Lovley 2008). An important point is that
they have self-sustaining anode-respiring mechanisms without the need of
artificial assistance, e.g., the supplementation of MFC with artificial
electron .
Schematic diagrams for a single-chamber MFC (A) and sediment MFC (B).
Shuttles. This finding is really important, when one consider the
application of MFC to waste treatment. Furthermore, with such bacterial
self-sustaining electron-transfer mechanisms, sediment MFC (this includes RPF
electricity generation) can also be constructed (Fig. 1B). We consider that
deeper understanding of bacterial self-sustaining electron-transfer mechanisms
will facilitate more efficient MFCs. (Kazuya Watanabe & Koichi Nishio)
Operated MFCs with
bio cathodes at which bacteria catalyze the electron transfer from the cathode
to electro positive terminal electron acceptors, such as oxygen or nitrate.
This resulted in a complete biological MFC with both bacteria at the anode and
cathode and therefore self-replenishing biological catalysts on just electrode
materials, such as carbon or graphite the circumvention Besides of expensive
metal catalysts, exciting recent work has shown that bio cathodes in
photosynthetic MFCs also reduce carbon dioxide(Co2). The aim of the present project is to study bioelectricity generation
in paddy plant microbial fuel cells.& objective To evaluate the factors
which induce bioelectricity generation by using paddy plant & ground soil
of paddy plant microbial fuel cell.
MATERIALS AND METHODS:
Collection of soil
sample:
Samples were collected in sterile polythene bags from paddy fields of
Lonavala.
Isolation and
identification of Bacteria:
Firstly soil sample were serially diluted and streaked on nutrient
agar plates and these plates were incubated at 370C for 24 hrs.
After incubation colonies having different colony characters .and studies
on colony morphological and bacterial
colony characters.
Maintenance of
culture:
Bacterial cultures were maintained on sterile nutrient agar slants and
storeed in a refrigerator.
Detection of current
formation:
Nutrient broth were prepared to check the efficiency current formation
medium was inoculated separately and then incubated. After 24 hrs. incubation
time current formation was measured. Using digital Multimeter.
RESULT AND
DISSCUSSION
RESULT:
Isolation
of bacteria:
The soil samples were collected from paddy fields of Lonavala. This
soil sample was use as a source of microorganisms the bacteria were isolated
from it and preserved for further studies.
Screening
of current forming bacteria:
After isolation of bacteria screened current forming
bacteria from which isolates. During screening of current forming bacteria, it
was noted that out of 6 isolates, only 2 isolates were current forming
capacity.
In the present study 6 different isolates were obtained from
paddy fields of Lonavala. Out of which 2 isolates were found to generate electricity.
Research conducted by Sample et.al show bacteria isolates from different
sources soil sample collected from agricultural land.
Identification of current forming bacteria:
Those organism which showed current producing capacity were
used for the identification purpose .With the help of morphological and biochemical
characters 2 isolates were identified..
Table no
.1 : Colony Characters of Electricity production isolates from paddy soil.
Sr. No
Bacterial Isolates
Size
Shape
Colour
Margin
Elevation
Opacity
Consistency
1
D1
1mm
Circular
Pigmented Green
Regular
Flat
Opaque
Moist
2
D2
1mm
Circular
Colourless
Regular
Flat
Opaque
Moist
Table no.
2 : Gram Nature & Motility
Sr. No
Bacterial Isolates
Gram Nature
Motility
1
D1
Gram
negative
Motile
2
D2
Gram
negative
Motile
Table no. 3 Biochemical Test
Bacterial Isolates
TEST
Glucose
Maltose
Manitols
Lactose
Indole
MR
VP
Citrate
Urease
Lysine
D1
A/G
A/G
–
A/G
–
+
–
+
+
–
D2
A/G
A/G
–
A/G
–
+
–
–
–
–
Table no.4 Identified Bacteria
Sr. No
Isolate Code
Identified up to species level
1
D1
Pseudomonas fluorescens
2
D2
Klebisella ozaenae
With the help of biochemical characterization it has
confermed that the current forming organism are Pseudomonas fluorescens,
Klebisella ozaenae.
Detection
and development of MFC:
The isolates organisms where separately incubated in
nutrient broth and kept for incubation for 370C. During incubation
electricity production was maintained every 24 hrs. .Electricity is measured by digital multi meter in the units
of millivolts. using anode copper (Cu) rods & cathods aluminum (Al) &
LED was burned .
Table no
.5: Detection of Current formation with the bacterial isolates
Hours
Pseudomonas fluorescens
Klebisella ozaenae
Current in nutrient medium
(mV)
Current in nutrient medium
(mV)
0
300mV
300 mV
24
666 mV
650 mV
48
710 mV
700 mV
72
823 mV
800 mV
96
764 mV
760 mV
It
was observed that there was an current formation after every 24 hrs. upto 96
hrs. with both the isolate cultures.
Production of Electricity Showing By LED
bulb.
Out
of The six isolates D1, D2 were found to produce electricity. The identified
isolates were Pseudomonas fluorescens, Klebsiella ozaenae. D1 isolate generates
more electricity than the D2 isolates.
Acknowledgement
We
would like to offer our sincere thanks to Dr. D. Y. Patil Arts, Commerce & Science College,
Dr.
Jayashri Pattan, Dr. Suneeta Paniker, Mrs. Sanchita Choubey, Mrs. Nivedita
Shelke ( All Department of Microbiology).
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