Abstract: The fermentation medium for producing alkaline mannose using konjac flour as the carbon source and soybean cake powder and sodium glutamate as the nitrogen source was optimized by Pluckett-Burman (PB) design, steepest ascent test and central composite design. Based on a central composite design for three independent variables including NaCl and sodium glutamate concentrations, a predictive mathematical model was built and validated. Meanwhile, scale-up production experiments were done in a 5-L fermentor. Our results indicated that the optimal fermentation medium (g/L) was composed of konjac flour 12, soybean cake powder 15, yeast powder 5, NaCl 84.4, sodium glutamate 3.11, K2HPO4 1.5, MgSO4 0.3, Na2CO3 10, and initial pH 9.5—10.0, yielding an alkaline mannose as high as 2610.1 U/mL.

Key words: alkaline mannanase, medium, optimization, steepest ascent test