RESUMO
Endophytic bacteria has the potential to produce antibiotics and other secondary metabolites. The production of secondary metabolites can be enhanced through the optimization of its nutrient content such as the nitrogen source. In this study, the content of nitrogen sources such as ammonium sulphate, ammonium dihydrogen phosphate, potassium nitrate and sodium nitrate have been modified and incorporated in the International Streptomyces Project Medium 4 broth media to optimize the growth of Streptomyces SUK 02. The extraction was carried out using ethyl acetate and the antifungal activity was assayed using agar diffusion method. The test fungus used was Aspergillus fumigatus and Fusarium solani. The results showed that the maximum weight percentage (w/v) of crude extract was obtained when sodium nitrate was used (3.30%), followed by ammonium dihydrogen phosphate (2.24%), ammonium sulfate (1.46%) and potassium nitrate (1.20%). Antifungal activity was obtained from the extracts that contained ammonium sulfat. The percentage of inhibition of this extract against Aspergillus fumigatus and Fusarium solani was 33.0-35.0% and 17.4-30.0%, respectively. Nevertheless, the MIC value against Aspergillus fumigatus was 1.5 mg/ml In conclusion, natrium nitrat was a suitable nitrogen source for optimum growth of Streptomyces SUK 02 whereas the presence of ammonium sulfat was good to increase the antifungal activity.