Study on fermentation conditions for oceanic red yeast strain RH1

We compared the effects of different carbon sources, nitrogen sources and inorganic salts on fermentation yield of oceanic red yeast (Rhodotorula sp.)RH1. By 4 factors and 3 levels orthogonal test, the optimum fermentation conditions for RH1 were determined: peptone 10 g · L^-1, yeast extract 15 g · L^-1, glucose 20 g · L^-1, MgSO₄ 0.25 g · L^-1, KH₂PO₄ 0.25 g · L^-1, NaCl 10 g · L^-1, inoculation amount 10%, initial pH 5.0, temperature 28 ℃, 80 mL medium in 500 mL triangle bottle, and fermentation time 48 h. Under above conditions, the cell biomass of RH1 can reach 10.46×10⁸ cfu · mL^-1, which increases by 23.9% as compared with the fermentation before optimization. An experiment of expanded culture is also conducted in a 25 L fermentation tank. The cell biomass of RH1 increased to 33.6×10⁸ cfu · mL^-1 in 28 h under the conditions of inoculation amount 8%, initial pH 5.0, revolution speed 350~400 r · min^-1, air ventilation volume 9 L · min^-1 and temperature 28 ℃. It is expected to further increase the biomass of strain RH1 by continuous filling of the materials.