Production of β-fructofuranosidase fromAspergillus flavus IBK-02 using orange peel as a low-cost substrate: Optimization through response surface methodology

Abstract

β-fructofuranosidases have wide applications in diverse industrial sectors such as the food, confectionary, and pharmaceutical industries. This study was aimed at the optimization of β-fructofuranosidase production from a filamentous fungus, under submerged  fermentation condition, using orange peel as a low-cost substrate. Fungi were isolated from decaying orange fruit and screened for β- fructofuranosidase production. The fungal strain with the most appreciable enzyme production was identified as Aspergillus flavus IBK-02  by the sequencing of the internal transcribed spacer region of the ribosomal DNA. β-fructofuranosidase production from the selected fungus was optimized using the conventional one-at-a-time approach by studying the effect of each of the medium parameters  incubation period, carbon sources, nitrogen sources, pH, and temperature on the enzyme production. Also, the influence of four  independent parameters (initial pH, temperature, inoculum concentration, and orange peel concentration) on β-fructofuranosidase  production was studied using the Box 2 Behnken Design (BBD) of response surface methodology (RSM). The coefficient of determination  (R ) obtained was 0.9600 showing that the quadratic model used for the prediction was significant (P>0.05). At the end of the experiment,  the optimal levels of the four significant variables (initial pH, temperature, inoculum concentration, and orange peel concentration)  were 6, 35 ^oC, 2.0% v/v, and 2% w/v, respectively, which produced 122.48 U/mL β-fructofuranosidase. The enzyme production increased by  about 5-fold in the optimum fermentation medium condition by RSM compared with the medium optimized through the onefactor-at-a- time approach. This study has revealed that the statistical process development for the production of β-fructofuranosidase from A. flavus  IBK-02, using orange peel as a low-cost substrate, could be used for industrial and biotechnological applications.