Parameters evaluation of fructooligosaccharides production by sucrose biotransformation using an osmophilic Aureobasium pullulans strain

摘要

The effects of production parameters on the biotransformation of sucrose in fructooligosaccharides (FOS) by osmophilic microorganisms Aureobasidium pullulans was evaluated by the RSM (Response Surface Metodology) exactly Plackett-Burman Design with 12 variables: concentration of sucrose, inoculum, yeast extract, urea, K_2HPO_4, (NH_4)_2SO_4, MgSO_4, ZnSO_4, MnSO_4. The strategy used was PB 16 with additional 3 central points, comprising 19 experiments. The levels of each variable (%) were sucrose: 20 a 40; yeast extract: 0 a 0.5; inoculum: 1 a 20; K_2HPO_4: 0 – 0.0435; urea: 0 – 0.015; (NH_4)_2SO_4: 0 – 0.033; MgSO_4.7H_2O: 0 – 0.0245; ZnSO_4: 0.0015; MnSO_4.7H_2O: 0 – 0.001, pH: 4.5 a 6.0; temperature (°C): 27 a 30; agitation (rpm): 150 a 250. The high yields reach values of 54.7% at 48h of reaction in treatment 9, 49.97% at 24h for treatment 4 and 49.34% in 24h for treatment 12. The variable effects were estimated for each parameter FOS Yield and total FOS concentration. The FOS Yield data showed significance at 24h the variables agitation, with negative effect -16.32 and p-value 0.016, MnSO_4, with positive effect 15.33 and p-value 0.020. At 48h the agitation was the only parameter significant with negative effect -14.94. The inoculum levels showed significance at 0h with positive effect 14.08, however it was negative at 24 and 48 hours. Regarding Total FOS Concentration, sucrose levels displayed p-values of 0.0085, 0.028 and 0.046 at 24, 48 and 72h respectively. MnSO_4 was the only mineral presenting stimulatory effect upon FOS concentration added. More research should be done to evaluate and optimize this process. This in turn can provide a focus for effective use of Aureobasidium pullulans to synthesize fructooligosaccharide through bioconversion using whole cells and obtaining the product by direct manner.