Abstract

The study was designed to investigate the effect of growth culture conditions, namely: Media composition, incubation period, temperature and pH on the production of antimicrobial compounds from three selected actinomycetes isolated from waste dump soil in  Western Uganda.  Molecular characterizations of these selected isolates were also carried out. Optimization processes were assessed using shake-flask cultures on eight different media, Portion of filtered fermentation broths were assayed using agar well diffusion method. The remaining portions were extracted using water, ethanol, ethyl acetate and methanol solvents. The extracts were dried and re-dissolved in 2.5% dimethyl sulphoxide to concentration of 2.5mg/ml and tested for antimicrobial activity using agar well diffusion method.  Three selected isolates were characterized using conventional PCR and sequenced using Sanger methods. The results showed that, Modified  Nutrient broth supplemented with carbon sources (soluble starch and Glycerol at half each) at 12-18g/l, 0816g/l and 10-18g/l for BRWDc (SP), KBMWDSb6 (M6) and KBRWDSa3 (RF) respectively produced optimum concentration of bioactive compounds. NaCl at concentration of 17-19g/l was found to be

suitable for optimum bioactive compound production. The best optimized results were found when cultures were grown under the following conditions: temperature (30-35oC), pH (7.0-7.5) and incubation period (168h). Aqueous and ethanol extracts gave optimum bioactive activity for all the three organisms. The identification of 16SrDNA gene showed that, the three isolates belong to phylum actinobacteria into the genus Streptomycetes. This study showed that media compositions, cultural conditions and solvents for extraction play role in bioactive compound production in these actinomycetes isolates.