Isolation and Molecular Identification of Antifungal Producing Rare-actinobacteria against Candida albicans

In last decades, fungal diseases have been treated by using antifungal antibiotics, e.g. azoles, polyenes and candicidines. Also, antifungal resistant Candida was evoluted, too and therefore, it needs to find new antifungal agents. Actinomycetes have been considered as main sources to find new antibiotics and various secondary metabolites during the last six decades. However, frequency of isolation of new metabolites from predominant actinomycetes (members of Streptomyces genus) reduced during two decades and therefore rare-actinomycetes have been used as promising sources to find new matabolites from various environments. In this research, antifungal producing rare-actinomycetes have been isolated from various soils of Iran.
Material and The soil samples were dried and appropriate dilutions were cultured on ISP2 agar. The morphology of colonies, microscopy and diaminopimelic acid test were examined on the isolates. Antifungal effect of the fermentation broth of the isolates was done against Candida albicans using well diffusion assay.
The results showed that among 50 actinomycetes isolates, 9 isolates have anti-Candida activity. The results of 16S rRNA gene analysis were revealed that the potent strains were belonged to Nocardia, Actinomadura, Streptomyces, Nocardiopsis, Martelella and Saccharomonospora.
Among the isolates, the strain UTMC 2325 had highest activity (34 mm) and had 98.84% similarity in 16S rRNA gene analysis to Nocardia rhamnosiphila. This research showed that the soils of Iran can be considered as promising sources to find antifungal producing actinomycetes.