Since infections have drastically increased during the last decades, it is a major goal to investigate the mechanisms underlying pathogenicity of L. corymbifera. One of the first barriers, which the fungus needs to cope with in the lung tissue, is phagocytosis by alveolar macrophages. Here, we report on phagocytosis assays for murine alveolar Target Selective Inhibitor Library macrophages co-incubated with resting, swollen and opsonised spores of a virulent and an attenuated L. corymbifera strain. A major finding of this study is the significantly increased phagocytosis ratio of the virulent strain if compared to the attenuated strain.

We quantify the phagocytosis by performing automated analysis of fluorescence microscopy images and by computing ratios for (i) fungal phagocytosis, (ii) fungal adhesion to phagocytes and Trichostatin A cell line (iii) fungal aggregation and spore cluster distribution in space. Automation of the image analysis yields objective results that overcome the disadvantages of manual analyses being time consuming, error-prone and subjective.

Therefore, it can be expected that automated image analysis of confrontation assays will play a crucial role in future investigations of host–pathogen interactions. The genus Lichtheimia belongs to the Mucorales (subphylum: Mucoromycotina) which counted as the most prominent order of the Zygomycetes, a class of the phylum Zygomycota.[1] Traditionally, the Zygomycota, are known as the most basal terrestrial phylum of the kingdom of Fungi. The phylum formerly comprised two classes, the Zygomycetes and the Trichomycetes, which differed by the ecological niches they inhabit. Whilst Zygomycetes mainly

occur as saprobionts in soil or 4��8C parasites and pathogens of plants, animals or other fungi, the Trichomycetes encompass phylogenetically diverse and unrelated groups of heterotrophic microorganisms which are united based on their ecological habitat and life style. They are typically endocommensals, particularly found in the digestive tract of the aquatic larvae of a number of insects or other arthropod host groups, including crustaceans and diplopods. The Zygomycota were eliminated as a coherent phylum because molecular phylogenetic analyses revealed its dispersal into five subphyla.[2-4] The phylogenetic relationships between these subphyla and their orders are not well resolved yet and are thus not well-understood so far. All five subphyla have the potential to form zygospores during conjugation of two yoke-shaped gametangia arising from compatible mating partners. The mucoralean genus Lichtheimia was formerly classified into the genus Absidia based on the Absidia-specific pyriform shaped collumellate sporangia but later designated to a separate phylogenetic lineage, which was designated into a separate family, the Lichtheimiaceae.[5, 6] Species within the genus Lichtheimia display features quite different from Absidia sensu stricto.