The inhibition effect of phenol on the production of Aspergillus niger inulinase and its modeling

The main objectives of this study were to investigate the effect of phenol on the production of Aspergillus niger A42 (ATCC 204447) inulinase and to model the best fermentation in the medium with inhibitor. When the phenol concentrations added into the fermentation medium increased from 0 to 5 g/L, the inulinase and invertase-type activities and the maximum inulinase and invertase-type production rates were reduced from 203.0 to 12.6 U/ml and from 156.9 to 3.1 U/ml, and from 32.6 to 2.9 U-1 center dot ml(-1) center dot day(-1) and from 32.6 to 1.1 U-1 center dot ml(-1) center dot day(-1). Additionally, the modified Gompertz, modified logistic, and Baranyi and Huang models successfully predicted the experimental data of inulinase production, invertase-type production, and substrate consumption, respectively. Consequently, renewable resources can be used in inulinase productions without detoxification when the hydrolysate contains low concentrations of phenol. Furthermore, the models can serve as universal equations in modeling the enzyme fermentation in shake flask fermentation.