A Contribution to Knowledge of the Actinomycetes in Rendzina of Zagrebačka gora

This is a study of Actinomycetes in the rendzinas of the Zagrebačka gora mountain occurring in localities above the village of Gračani. An analysis of the mean frequencies of Actinomycetes and Fungi has proved that there exist differences in the number of these organisms under varied types of vegetation. Thus, for instance in a Pine forest was established a sailer number of Actinomycetes than under the cover of the forest association Querco-Ostryetum. Most of Actinomycetes were established in surface soil horizons, while they decrease with soil depth. In all samples prevail strains with colourless vegetative mycelium. There are also conspicuous differences in the pigmentation of the vegetative mycelium under varied types of vegetation, which is exhibited by the frequencies of the pigmented strains. Parallel with soil depth decreases also the percentage of antagonistic strains. The number of antagonistic strains of Actinomycetes is higher in a soil covered by the forest community Querco-Ostryetum. In a soil under Pine forest were established 7 series of antagonistic Actinomycetes, under the Querco-Ostryetum association 12 series. Most frequently were present the series Nigrescens (Blackish), Coerulescens (Bluish), and Violaceus (Violet-coloured). Noticed were also representatives of the series Ruber (Red), which is not so frequent in the continental soils of Croatia. In a soil under Pine forest the following species were found: Actinomyces bicolor, A. longispororuber, A. violaceorectus, A. roseoviolaceus, A. nigrescens, and A. chromogenes. All the mentioned species were also established under the association Querco-Ostryetum, under which were also found A. globisporus, A. griseus and A. cylindrosporus. Out of the analysed antagonistic strains of Actinomycetes 68% possess sporophores curved into spirals and the rest possess rectilinear sporophores. The species Escherichia coli is affected by 20%, the Bacillus subtilis by 90%, the Bacillus mycoides by 86%, the Staphylococcus aureus by 85%, und the yeastlike microorganism Candida albicans by 68% of antagonistic Actinomycetes strains