Optimization of the Production of α-L-Rhamnosidase by Aspergillus niger in Solid State Fermentation Using Agro-Industrial Residues

Abstract

ABSTRACT The enzyme α-L-rhamnosidase specifically cleaves terminal rhamnose residues from awide variety of natural products. This property endows this enzyme with importantbiotechnological potential as L-rhamnosidase could be employed in a variety ofapplications, including removing bitterness from citrus fruit juices, improving the aroma ofwines and converting clinically important steroids. This work optimized α-L-rhamnosidasesolid-state fermentation production from Aspergillus niger 426 using statistical methods.Firstly, a statistical mixture-design with three components to determine the best ratio ofnutrients for enzyme production was carried out. The optimal conditions consisted ofgrowing the fungi in media containing 0.14 g of cane sugar bagasse, 1.25 g of soybeanhulls and 3.05 g of rice straw; these conditions achieved a maximum α-L-rhamnosidaseactivity of 1.92 U / mL. Next, a 3² Box-Behnken design to optimize culture moisture levelsand nutrient solution pH values for enzyme production was carried out. α-L-rhamnosidaseactivity increased to 3.02 U / mL when medium moisture was 75.5% and pH value of4.0.Original Research Article