Cameron L. Jones

Decolourisation of a pigment plant effluent by Pycnoporus cinnabarinus in a packed-bed bioreactor

SummaryThe decolourisation of wastewater from a pigment plant by the white-rot fungus Pycnoporus cinnabarinus was studied in a packed-bed bioreactor. Decolourisation was first observed 48 to 72 h after inoculation and was followed using UV/VIS spectrophotometry. An assessment of the inhibitory properties of the effluent on the growth of Pycnoporus cinnabarinus showed that this fungus can tolerate high levels of potentially toxic waste.

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 × 103 to 41.7 × 103 s−1. The highest D value was shown at a shear rate of 27.8 × 103 s−1 for 30 s, implying greatest homogeneity in the size distribution function over the measured range (0–500 μm2). 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 express the fragment diversity whereas the reciprocal fractal valie characterizes the distribution size probability. Image-analysis methodology is described and the implications of a fractal description of a mycelial inoculum are also considered.

Understanding Fractal Analysis? The Case of Fractal Linguistics

Terms such as ‘self-similarity’, ‘space filling’, ‘fractal dimension’, and associated concepts have different meanings to different people depending on their background. We examine how methodology in fractal analysis is influenced by diverse definitions of fundamental concepts that lead to difficulties in understanding fundamental issues. The meaning of terms associated with fractal analysis needs to be clarified if this method is to be useful in diverse disciplines. It is our premise that communications that are result focused constitute a danger in perpetuating misconceptions of terms due to the concise nature of the writing and the reliance on references to fill in the procedural and conceptual gaps. Communicating effectively requires a sound understanding of the terminology and a clear and meaningful presentation. We address here communication and the nature of scientific discourse, ‘fractal linguistics’.

Prediction of phenol-oxidase expression in a fungus using the Fractal Dimension

The filamentous white-rot fungus Pycnoporus cinnabarinus secretes extracellular phenol-oxidases. This paper demonstrates that the Fractal Dimension of branching complexity can be used to predict the generalized yield of this oxidase in submerged culture. This confirms a positive correlation between the amount of hyphal tip branching and exo-enzyme secretion in this fungus, and under these conditions.

The effect of temperature and culture medium on the degradative activity of Phanerochaete chrysosporium evaluated using three qualitative screening methods

Abstract The lignin-degrading ability of Phanerochaete chrysosporium (1547) and (1556) is well established and thus qualitative screening tests for lignin degradation should indicate that they are capable of carrying out this function. In this report we show the high degree of dependence of these qualitative screening methods on temperature and, more importantly, growth medium. Under certain conditions such qualitative screening tests utilising gallic acid, guaiacol and Remazol brilliant blue R will give reactions that would suggest that these two white-rot fungal strains are not lignin degraders.

Histochemical detection of laccase in Pycnoporus cinnabarinus using microwave-enhanced colloidal gold microcrystallization

Laccase was detected histochemically in Pycnoporus cinnabarinus fungal hyphae by growing the organism on cellophane or microporous polycarbonate membranes overlaid on malt extract agar. Membrane sections were stained with a reagent of 2,6-dimethoxyphenol and colloidal gold for 30 min and irradiated for 24 s at maximum output in a microwave oven. Laccase was detected as purple-blue deposits at the apical tip region in high concentrations, and at lower levels on the exterior, sub-apical hyphal sheath.

The use of image analysis for spore counts of white-rot fungi

An improved method has been developed for the determination of fungal spore counts using a haemocytometer. The method uses a personal computer with a frame grabber card and commercial imaging software. Semi-automation using an iterative programming technique was implemented to count the spores produced byPhanerochaete chrysosporium. Rapid and reliable counts were achieved using image processing.

The use of digital image segmentation to quantify an aminoanthraquinone dye biotransformation by white-rot fungi

Three methods are presented for the objective, digital evaluation of Remazol Brilliant Blue R dye biotransformation by the white rot fungi, Pycnoporus cinnabarinus and Phanerochaete chrysosporium. This screening technique uses computerized image analysis and a binary logical and function to provide a rapid (2 min per analysis), quantitative, digital densitometry interpretation of enzyme induced chromophore conversion by fungi. A kinetic measure of metabolic activity (enzyme activity coefficient, μ) may also be determined. It is shown that chromophore conversion is more rapid and extensive by P. cinnabarinus.

Specimen preparation for high contrast image processing and fractal analysis of branching fungal colonies

A rapid method is presented for the aerosol dispersion of fungal spores onto microporous polycarbonate membrane overlays in petri-dish agar culture, using an air-brush apparatus. Nebulizer inoculation results in the growth from single spores of discrete, filamentous colonies which can be immobilized, fixed, and stainedin situ using Coomassie Brilliant Blue R. High contrast microscopy and image-processing is facilitated using Poretics Cyto-Clear™ glass slides. This technique was developed specifically for the fractal analysis of branching and the measurement of other morphological parameters in fungi. Emphasis is directed towards the ligninolytic fungi,Pycnoporus cinnabarinus andPhanerochaete chrysosporium.