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Optimal conditions such as temperature, moisture and nitrogen source are important factors for enzyme production by microorganism. Therefore, this study investigated the optimal conditions and nitrogen sources for mannanase production from Aspergillus niger TISTR3013 using rice bran as a solid medium. Two experiments were conducted in this research. The first experiment was studied the optimal conditions for mannanase production from A. niger TISTR3013, moisture of medium (50, 60 and 70 percent), incubation temperature (30, 45 and 60 ºC) and pH of medium (5, 7 and 9). The fermentation period was 3 days. The results showed that the optimal moisture, temperature and pH for mannanase production were 60 percent, 30 ºC and pH 7, respectively, which produced mannanase at 763.89 U/g DM (p < 0.01). The second experiment was studied optimal nitrogen source for mannanase production from A. niger TISTR3013, 1 % ammonium sulfate supplementation, 1 % urea supplementation and the control (without nitrogen supplementation). The result showed that 1 % ammonium sulfate is the most suitable nitrogen source which produced maximum mannanase enzyme at 919.47 U/g DM. The enzyme production was 1.2 folds increase when compared to that of the control (740 U/g DM) (p < 0.01). Furthermore, the results from these experiments indicated that rice bran could be used as a medium for mannanase production from A. niger TISTR3013.
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