Optimization of Trehalose Production by Rhodotorula dairenensis Following a Sequential Strategy of Experimental Design

Initially, a technical screening was applied to select yeasts with a potential for trehalose production using thermal stress for the induction of synthesis. The effects of the concentrations of sugar cane molasses, corn steep liquor and a commercial yeast extract Prodex Lac SD (R), and of pH and temperature on the biomass were studied using a fractional design followed by a central composite rotatable design (CCRD). The optimum values were 50 g/l for the molasses and corn steep liquor concentrations, initial pH of 5.5, and temperature of 30 degrees C, with no yeast extract. Under these conditions, the production of trehalose was studied using a CCRD to optimize the temperature (33 to 47 degrees C) and exposition time (60 to 120 min) of the cultures to the thermal stress. The maximum intracellular trehalose content reached was 20.5% (g trehalose/100 g dry cell) at temperatures of 35-40 degrees C and with 100-120 min of exposition time to the thermal stress.