Ultrasonic Characterization of Mycelial Morphology as a Fractal Structure

Abstract

Preliminary measurements of scattering of ultrasound from filamentous microorganisms in aqueous-medium suspensions are reported. The data are used to characterize the structuring (morphology) between the organisms quantitatively by modelling the morphology in terms of fractal structures and obtaining the fractal dimension as the characteristic parameter. The fractal dimension is calculated from the slope of a log-log plot of scattered intensity versus the scattering vector magnitude. The intensity is measured over a range of magnitudes of the scattering vector by varying the scattering angle as well as the ultrasonic frequency. Results from microbial suspensions of different species and different morphologies indicate that the fractal dimension can be used to quantify the morphological state of a suspension. The fractal dimension ranges from around 1.5 for suspensions with pelletous morphology to around 2.5 for suspensions with filamentous morphology.

Keywords

Fractal dimension mycelial morphology scattering vector ultrasonic scattering

Get full access to this article

View all access options for this article.

References

Metz

Kossen

N.W.F.

, The Growth of molds in the form of pellets - a literature review, Biotech. Bioeng. 19, 781–799 (1977).

van Suijdam

J.C.

Metz

, Influence of engineering variables upon the morphology of filamentous molds, Biotech. Bioeng. 23, 111–148 (1981).

Davis

R.H.

Hunt

T.P.

, Modelling and measurement of yeast flocculation, Biotech. Prog. 2, 91–97 (1986).

Schaefer

D.W.

Martin

J.E.

Wiltzius

Cannell

D.S.

, Fractal geometry of colloidal aggregates, Phys. Rev. Lett. 52, 2371–2374 (1984).

Meakin

, Fractal aggregates, Adv. Colloid. Int. Sci. 28, 249–331 (1988).

Ganczarczyk

J.J.

, Structure of activated sludge floes, Biotech. Bioeng. 35, 57–65 (1990).

Muthukumar

, Dynamics of polymeric fractals, J. Chem. Phys. 83, 3161–3168 (1985).

Aunins

J.G.

Carrondo

M.J.T.

Wang

D.I.C.

, Microbial and inorganic floe structure and transport properties: a fractal geometric description, private communication.

Jullien

Botet

, Aggregation and Fractal Aggregates, pp. 24–51 (World Scientific Publishing, Singapore, 1987).

10.

Kjems

J.K.

Freltoft

, Neutron and x-ray scattering from aggregates, in Scaling Phenomena in Disordered Systems, NATO ASI Series B: Vol. 133, Pynn

Skjeltorp

eds. (Plenum Press, New York, 1985).

11.

Vicsek

, Fractal Growth Phenomena, pp. 72–77, (World Scientific Publishing, Singapore, 1989).

12.

Waag

R.C.

Lerner

R.M.

Gramiak

, Swept-frequency ultrasonic determination of tissue macrostructure, in Proc. Seminar on Ultrasonic Tissue Characterization, Linzer

, ed., NBS Spec. Publ. 453, pp. 213–228 (1976).

13.

Waag

R.C.

Lee

P.P.K.

Persson

H.W.

Schenk

E.A.

Gramiak

, Frequency-dependent angle scattering of ultrasound by liver, J. Acoust. Soc. Am. 72, 343–352 (1982).

14.

Javanaud

, The application of a fractal model to the scattering of ultrasound in biological media, J. Acoust. Soc. Am. 86, 493–496 (1989).

15.

Morse

P.M.

Ingard

K.U.

, Theoretical Acoustics, pp. 407–439 (McGraw-Hill, New York, 1968).