“…With respect to the nitrogen source, yeast extract was replaced with several organic and inorganic sources, namely, peptone, potassium nitrate, ammonium nitrate, di-ammonium phosphate, ammonium chloride, ammonium sulphate, sodium nitrate, urea, ammonia, ammonium ferrous sulfate, and monosodium glutamate, all at a final concentration of 5 g/L. Different pH (3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0), temperature (20,25,30,35, and 40°C) and incubation times (1 ~ 15 days) were also studied.…”