Screening of agroactive and bioactive compounds produced by rhizospheric actinomycetes isolates and production medium optimization

In this thesis, agroactive and bioactive compounds production from actinomycetes isolated from rhizosphere regions of different plants in terrestrial and aquatic habitats were screened qualitatively and quantitatively. Among the 42 actinomycetes isolated from the study, 6 isolates that showed the highest production for different activities were identified by using molecular methods. In the primary and secondary screening of bioactive compound production, antibacterial and antifungal activities of the isolates were determined by inhibition zones against 6 bacterial (Bacillus cereus, Staphylococcus aureus, Enterecoccus faecalis, Pseudomonas aeruginosa, Echerichia coli and Salmonella typhimurium) and 2 fungal pathogens (Aspergillus niger and Candida albicans). According to these screening results, Streptomyces labedae isolate CYP25 (Accesion No: MK254642) and Streptomyces sp. isolate CYP30 (Accession No: MK254643) selected as the best isolates for antibacterial and antifungal activities respectively for optimization studies. Streptomyces labedae isolate CYP25 (Accesion No: MK254642) showed the highest antibacterial activity in screening with ethyl acetate extracts on Actinomycetes Isolation Broth (AIB) against S. aureus (18 mm) at the optimization step. Streptomyces sp. isolate CYP30 (Accession No: MK254643) showed the highest antifungal activities against C. albicans (60 mm) and Alternaria sp. isolate D21 (52 mm) in Glucose Soy Bean Meal Broth (GSB) and showed the highest antifungal activity against A. niger (16 mm) in ISP-3 (International Streptomyces Project-3) Broth. The isolates were screened qualitatively and quantitatively during the screening of agroactive compound production. In screening of IAA production, the highest production was performed by Nocardiopsis sp. isolate CYP39 (Accesion No: MK254645) (51,04 µg/ml). In the optimization of production media of IAA performed at different concentrations of L-tryptophan, this isolate produced the highest amount of IAA (76.5 µg/ml) on the 13th day of incubation at 0.9 g % L-tryptophan-containing medium. Among the 42 rhizospheric actinomycetes isolates, 32 were identified as siderophore producers as a result of qualitative screenings made on Chrome azurol S (CAS) agar. In experiments performed on ISP-2 agar with glycine, the best HCN producer was Nocardiopsis sp. isolate CYP15 (Accesion No: MK254640). In the qualitative screening of phosphate solubility, the two isolates (Streptomyces moderatus isolate CYP35 (Accesion No: MK254644), Streptomyces chartreusis isolate CYP19 (Accesion No: MK254641)) constituting the highest halo-zone diameter were selected for quantitative screenings. In this experiments, Streptomyces moderatus isolate CYP35 (Accesion No: MK254644) has showed with the highest activity of 196.4 µg / ml on the 9th day of incubation. Key words: Rhizosphere, actinomycetes, agroactive compunds, bioactive compounds