Enhancement of dextransucrase activity of <i style="">Pediococcus</i> <i style="">pentosaceus</i> mutant SPAm1 by response surface methodology

Abstract

In the present investigation, an optimal fermentation medium for the production of dextransucrase from mutant SPAm1 of a natural isolate of <i style="">Pediococcus</i> <i style="">pentosaceus</i> (GenBank Acc. No. EU569832) was developed following response surface method. A two-level Plackett-Burman design (PBD) and five-level Central composite design (CCD) was combined to optimize the medium composition for enhancement of the dextransucrase activity of SPAm1. A second-order model equation was suggested and validated experimentally. The model adequacy was very satisfactory as the coefficient of determination was 0.958. The optimum values for the tested variables were; sucrose 55.2 g/L; beef extract 2.3 g/L and Tween 80 8.3 mL/L. The predicted dextransucrase activity after response optimization was 15.9 U/mL, whereas the experimental value was 15.6 U/mL at 16 h of incubation, which showed a 3.2-fold enhancement over the enzyme activity (4.9 U/mL) of mutant SPAm1 given by the unoptimized medium. However, the increase in dextransucrase activity by SPAm1 after optimization of the medium was an outstanding 4.6-fold higher over that of the wild-type <i style="">P.</i> <i style="">pentosaceus </i>from the unoptimized medium (3.4 U/mL).