ULTRASONIC INVESTIGATIONS ON NON-LINEAR GROWTH PHASES OF DIFFERENT BACTERIA CULTURES BY USING ULTRASONIC PARAMETERS

M Srinivasa Reddy, R V Sudheer Kumar, S Shankaraiah, D Linga Reddy

Abstract


Ultrasonic velocity and attenuation coefficient were measured in batch cultures to study non-linear growth properties of E.coli, S. epidermidis, P.multocida and B.subtilis. An unconventional ultrasonic Pulse Echo Overlap (PEO) technique was adopted for measurement of ultrasonic parameters. The results were compared with the conventional establishing measuring techniques involve direct microscopic counts and indirect viable cell counts. The batch cultures were prepared for growth periods of 6, 12, 18, 24, 30, 36, 42 and 48 hrs. The 2 and 10 MHz ultrasonic frequencies were selected based on Rayleigh-plesset’s bubble activation theory. It was found that ultrasonic velocity and attenuation coefficient were linearly increased in exponential phase, almost constant in stationary phase and slightly decreased in death phase. The results of ultrasonic velocity and attenuation coefficients of different bacteria cultures were found in the right order of magnitude and aligned with the theory proposed by A Zips and U Fast.  It was learnt that the ultrasonic velocity and attenuation coefficients depend on relative cell size, shape, wall structure and characteristic arrangement of cell groups.  Finally, in this paper it was proposed that the measurement of ultrasonic parameters with pulse echo overlap technique could be emerged as alternate technique   to estimate the non-linear growth properties of different bacteria cultures.


Keywords


Ultrasonic Velocity, Attenuation, Pulse echo overlap technique and Bacteria cultures.

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