Fungal spores are used in the laboratory for culture maintenance and at laboratory and other scales as inocula for fermentations. The spore swelling and germination processes constitute a major part of the lag phase, and the subsequent culture morphology and productivity can be greatly influenced by the initial concentration and condition of the spores. An image analysis method has been developed for assessing the viability and the germination characteristics of fungal spores in submerged cultures. Structural variations during germination, i.e., swelling, germ tube formation, and germ tube elongation, are measured in terms of distributions of spore volumes and of germ tube lengths and volumes. These measurements are fully automatic and give a very rapid assessment of spore viability. This image analysis method might be used as a tool in culture maintenance and for determining the quality of inocula for fungal fermentations.

A link between vacuolation and fragmentation of Penicillium chrysogenum mycelia in stirred tank submerged fermentations is reported. Quantitative information on vacuolation and morphology was obtained by image analysis. In fed-batch fermentations the coincidence of the events of rapid vacuolation and the fall of the mean total and main hyphal lengths suggests that hyphal fragmentation is not necessarily due to "shear" alone. The physiological state of the hyphae, characterized by the proportions of vacuoles, was found to have a significant influence on the breakage of mycelial hyphae. It was found that the fragmentation was greater when the hyphae became heavily vacuolated following nutrient limitation in the culture, i.e., during the switch from the rapid growth to the production phase. 0 1994 John Wiley & Sons, Inc.

The application of the radial-flow growth chamber to the study of the initial stages of bacterial adhesion to surfaces under flowing conditions is reported. The adhesive properties of the bacterium Pseudornonns fluorescens (NCIB 9046) to stainless steel (type AISI 316) were found to be highly dependent on surface shear stress and the time and concentration of cells used in the incubation procedure. Maximum levels of adhesion occurred in zones of lowest surface shear stress, particularly less than 6-8 Nm-*. Adhesion was still noticeable at shear stresses even up to 130 Nm-2. Significant detachment of cells from a monolayer attached under static conditions was found to occur at surface shear stresses in excess of 10-12 Nm-2.

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The application of the radial-flow growth chamber to the study of the initial stages of bacterial adhesion to surfaces under flowing conditions is reported. The adhesive properties of the bacterium Pseudomonas fluorescens (NCIB 9046) to stainless steel (type AISI 316) were found to be highly dependent on surface shear stress and the time and concentration of cells used in the incubation procedure. Maximum levels of adhesion occurred in zones of lowest surface shear stress, particularly less than 6-8 Nm(-2). Adhesion was still noticeable at shear stresses even up to 130 Nm(-2). Significant detachment of cells from a monolayer attached under static conditions was found to occur at surface shear stresses in excess of 10-12 Nm(-2).