Optimal conditions for the production of sulfated polysaccharide by marine microalga Gyrodinium impudicum strain KG03.

A marine microalga Gyrodinium impudicum strain KG03 produced sulfated exopolysaccharide designated as p-KG03, which showed a strong antiviral activity against encephalomyocarditis virus (EMCV). To optimize culture conditions for the production of p-KG03, mineral salts, vitamins, plant growth hormones, temperature, pH and light conditions were examined. From this study, M-KG03 medium for the maximum production of p-KG03 was suggested as follows; NH(4)Cl 75 microM, NaH(3)PO(4) 200 microM, NaHCO(3) 50 microM, Na(2)SO(4) 10 microM, FeCl(2) x 6H(2)O 10 microM, MnCl(2) x 4H(2)O 0.1 microM, vitamin B(12) 0.75 microg, naphthalene acetic acid (NAA) 7.5 microg and myo-inositol 200 mg per liter of aged sea water. The optimal temperature and pH were 22.5 degrees C and 8.0, respectively. The optimal light conditions of intensity and period were 150 microE m(-2) s(-1) and 16:8 h light:dark cycle. Finally, the cell growth and p-KG03 production were measured in one liter of M-KG03 medium with 1% CO(2) and 50 ml min(-1) of airflow using two liters airlift balloon type photobioreactor (ABTPR). At these optimal conditions, p-KG03 production and cell growth were 134.6+/-5.9 mg l(-1) and 123,076+/-1,597 cells ml(-1), respectively, representing a 7.7 and 5.1 times compared with f/2 medium with Erlenmeyer flask culture (p-KG03 production 17.5+/-1.3 mg l(-1) and cell growth 24,311+/-1,291 cells ml(-1)).