Morphological recognition of fungal spore germination by a computer-aided image analysis and its application to antifungal activity evaluation

An automatic image analysis system has been developed for measuring the germination characteristics of fungal spores and assessing the antifungal activity of antifungal agent against fungal spore germination in liquid medium. The system is composed of a multi-well culture chamber, automatic stage, microscopic observation system, image analyzing system, and computer program. An image of spores displayed on a TV monitor was converted to the binary brightness image by properly adjusting the threshold brightness level. The binary image was further analysed by using a curvature-based shape representation technique. ?Thus obtained profile of each spore was expressed by the combination of four line elements: line, convex, concave, and apical. From these morphological characteristics of spore, the germinated spores could be discriminated. This system was successfully applied to the assessment of antifungal activity of amphotericin B against fungi: Aspergillus fumigatus, Curvularia lunata, and Fusarium solani.