Optimization of Poly(β-L-malic acid) Production Using Aureobasidium Pullulans by Response Surface Methodology

Plackett-burman (P-B) and response surface methodology (RSM) were used to optimize the conditions of Poly (beta-L-malic acid) production by Aureobasidium pullulans. Results of the statistical analysis showed that the concentration of Poly(beta-L-malic acid) was influenced by the concentrations of initial glucose, (NH4)(2)SO4, CaCO3 and agitation speed, liquid loading, and incubation time. The optimized fermentation conditions performed in shaking flasks were glucose 100.428g/L, (NH4)(2)SO4 3.06g/L, succinic acid 2g/L, K2CO3 0.4g/L, KH2PO4 0.1g/L, CaCO3 27.7g/L, ZnSO4 center dot 7H(2)O 5x10-5g/L, MgSO4 center dot 7H(2)O 0.1g/L, and corn steep liquor 0.1% (v/v), liquid loading 55mL/500mL, temperature 25 degrees C, agitation speed 207 r/min, and incubation time 152h. Under which the maximum Poly(beta-L-malic acid) concentration of 3.897 +/- 0.472g/L was obtained at the optimum conditions, which significantly increased by 218.8% compared with the control (1.781 +/- 0.342 g/L).