Poster Presentation Model

Study of Ultrasonic Parameters on Non-linear Growth Curve of B.
Subtilis
Srinivasa Reddy M1, K Sathi Reddy2 and Linga Reddy D3
Abstract: A novel unconventional ultrasonic Pulse Echo Overlap (PEO) technique is introduced to measure non-
linear growth properties of B.subtilis bacteria cultures. The results are compared with the conventional
establishing measuring techniques involve direct microscopic counts and indirect viable cell counts. In the
present paper, ultrasonic velocity and attenuation coefficients are used to estimate the non-linear growth
properties of B.subtilis. The ultrasonic frequencies of 2 MHz and 10 MHz are selected based on Rayleigh-plessets
bubble activation theory
Results & Discussions
In the recent years, the measurement of ultrasonic velocity

and attenuation coefficient has been adequately employed
in understanding biological effects induced by ultrasound
in macromolecules, microorganisms, tissues, organs and
bones etc . The velocity of an ultrasound wave through a
medium varies with the physical properties of the medium.
As an ultrasound beam penetrates a medium, energy is
removed from the beam by absorption, scattering, and
reection that refers to attenuation. Therefore, ultrasonic
velocity and attenuation coefficient are usually employed
to study non-linear growth properties of B.Subtilis.
0.50
1700
)n
ep/cm
cm
/sec
2
0.40
1660
1640
1620
A
ttenuationcoefficient (
U
ltrasonicV
elocity(v)x10
1580
1560
1540
1520
1400
1200
0.6
0.30
1000
0.5
800
0.15
0.10
10
20
30
Growth period (t) hrs
40
50
0.4
600
0.3
400
0.2
200
0.05
0.1
0.00
0.0
-0.05
0
1/31/2014
0.35
0.20
1500
Schematic view of ultrasonic measurements
1600
0.7
0.25
1600
The ultrasonic transducer of 10mm gap

between transmitting and reflecting surfaces
is immersed into the vessel. The other end of
the
transducer
is
connected
to
the
ULTRASONIX
4400M
(Roop
Telsonic
Ultrasonix Limited, Mumbai.) by BNC cable
and Pulse Echo pattern was observed on the
CRO screen and
displays the ultrasonic
velocity. The ultrasonic velocity is measured
in microbial cultures grown for the period of
6hrs, 12hrs, 18hrs, 24hrs, 30hrs, 36hrs, 42hrs
and also for the sonication of 1 min to
maximum of 16 min in steps of one minute.
The sonication vessel kept inside the water
bath which is maintained at constant
temperature of 300 K by using automatic
temperature control bath. The attenuation
coefficients of the bacteria cultures are carried
out by measuring the amplitudes of
transmitted pulses of selected two successive
echoes on CRO screen.
0.8
0.45
1680
10
20
30
40
50
C
o
lo
n
yF
o
rm
in
gU
n
its(C
F
U
/m
l)
It seems that the ultrasonic velocity increases

linearly in the exponential phase, and becomes
maximum in the stationary phase and finally
decreases
in the death phase.
Attenuation
coefficient also follows the similar trend.
The ultrasonic velocity for microbes linearly
increases in exponential phase because the
constant rate of increase of cfu/ml linearly
decreases intermolecular free length and hence
adiabatic
compressibility.
The
attenuation
coefficient increases mainly due to increase in the
intrinsic absorption and scattering losses with
growth period. Usually intrinsic absorption
dominates at 10 Mhz.
From the figures it is observed that
the
variation of ultrasonic velocity and attenuation
coefficient are in good agreement with CFU/ml
2MHz
and optical density
10MHz
O
p
tic
a
lD
e
n
s
ity(O
.D
.)
Introduction
-200
0
10
20
30
40
50
Conclusions
It was learnt that the ultrasonic velocity and

attenuation coefficients depend on relative size,
shape, cell wall structure and characteristic
arrangement of cell groups.
Therefore, it is
hypothesized that this novel technique could be
used to measure
the growth properties of the
Acknowledgements
other
bacteria
cultures. the Head, Dept. of Physics, O
MSR
gratefully
acknowledge
U.
MSR is also thankful to the Management and Principal
Anurag Group of Institutions, Venkatapur, Hyd. for their
encouragement and financial support.
NSAMEA-2014, Department of Physics, Osmania University

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Study of Ultrasonic Parameters on Non-linear Growth Curve of B.

Results & Discussions

In the recent years, the measurement of ultrasonic velocity

Growth period (t) hrs

Schematic view of ultrasonic measurements

The ultrasonic transducer of 10mm gap

Growth period (t) hrs

It seems that the ultrasonic velocity increases

Growth period (t) hrs

It was learnt that the ultrasonic velocity and

NSAMEA-2014, Department of Physics, Osmania University

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