MYCELIAL FRAGMENT SIZE DISTRIBUTION - AN ANALYSIS BASED ON FRACTAL GEOMETRY

The use of white-rot fungi for biodegradative research and developmental application requires seeding with a suitable inoculum. This paper presents a new method for the quantitative analysis of a mycelial inoculum composed of homogenized hyphal fragments. Our method is premised on a power-law behaviour between frequency and the size of these mycelial fragments. It is shown that the fragment distribution profile can be determined by regression to give the fractal fragmentation dimension, D. The influence of homogenizer speed was also investigated over a range from 8333 rpm to 25 000 rpm, which corresponds to a shear rate range of 13.9 x 10(3) to 41.7 x 10(3) s-1. The highest D value was shown at a shear rate of 27.8 x 10(3) s-1 for 30 s, implying greatest homogeneity in the size distribution function over the measured range (0-500 mum2). As shear force and duration increases (up to a threshold value) the production of small fragments is facilitated with a corresponding decrease in the D value. The slope relation expresses the fragment diversity whereas the reciprocal fractal value characterizes the distribution size probability. Image-analysis methodology is described and the implications of a fractal description of a mycelial inoculum are also considered.