Optimization of Medium Composition and Condition for Agarase Production by Marine Streptomyces BLH 3-7

Abstract

A marine bacteria Streptomyces BLH 3-7 from Bitung Sea Sulawesi were isolated and observed to produce agarase enzymes in basic ISP2 media. To improve the agarase production, different carbon, nitrogen, pH, and minerals were compared to observe their effects on the agarase production through one factor at a time (OFAT) method. By selecting the best factor one at a time, the optimized media has agarase production at 5,943 U/mL, a 530% increase compared to the basic ISP2 media at 0,9435 U/mL, after 168 hours of culture incubation. The following media compositions are 1% malt extract, 0.5% agarose, 3% artificial sea water (ASW), 1% maltose, 0.4% ammonium sulfate, 0.5% cobalt(II) sulfate hexahydrate, and pH 5. It was observed in screening that the usage of peptone had negative effects on agarase production. The addition of maltose alongside agarose as carbon sources had a positive effect on the agarase production with no carbon catabolite repressor observed in all carbon sources. The cultures were observed to prefer inorganic nitrogen (ammonium sulfate or natrium nitrate) compared to organic nitrogen (yeast extract, tryptone, and urea) for agarase production. Streptomyces BLH 3-7 had a stable agarase production range at pH 5-9 and diminished at pH 10. To further analyze the interaction effect between the factors, response surface methodology is recommended for the next step of optimization.