Improvement of β-Glucosidase Production by Protoplast Fusion Between Aspergillus Oryzae 3.481 and Aspergillus Niger 3.316 Using Response Surface Methodology

ABSTRACT

β-Glucosidase production by protoplast fusion between Aspergillus oryzae 3.481 and Aspergillus niger 3.316 in shake flask culture was optimized by statistical analysis using response surface methodology (RSM). The fused protoplasts had been regenerated on a specific medium and fusants were selected for further studies. Screening of variables to find their relative effect on β-glucosidase production was done using single-factor test and analysis of variance (ANOVA). The effect of substrate concentration and initial pH on β-glucosidase production was studied. The initial pH and concentration of mixed carbon source of bran and starch, ammonium sulphate, CaCl₂ and KCl, were found to influence the enzyme production significantly. The optimal levels of these variables and the effect of their mutual interactions on β-glucosidase production were determined using Box-Behnken design. This led to a further optimization of the fermentation conditions to achieve higher enzyme activities, which reached 4.124 U/mL.

Keywords:

• β-glucosidase
• response surface methodology
• fusion strains
• Aspergillus oryzae
• Aspergillus niger