Enzymatic properties of α-L-rhamnosidase and the factors affecting its activity: a review / 生物工程学报

α-L-rhamnosidase is a very important industrial enzyme that is widely distributed in a variety of organisms. α-L-rhamnosidase of different origins show functional diversity. For example, the optimal pH of α-L-rhamnosidase from bacteria is close to neutral or alkaline, while the optimal pH of α-L-rhamnosidase from fungi is in the acidic range. Furthermore, the enzymatic properties of α-L-rhamnosidases of different origins differ in terms of the optimal temperature, the thermal stability, and the substrate specificity, which determine the different applications of these enzymes. In this connection, it is crucial to elucidate the similarities and differences in the catalytic mechanism and substrate specificity of α-L-rhamnosidase of different origins through analyzing its enzymatic properties. Moreover, it is important to explore and understand the effects of aglycon and metal cations on enzyme activity and the competitive inhibition of L-rhamnose and glucose on enzymes. These knowledge can help discover α-L-rhamnosidase of industrial significance and promote its industrial application.

α-L- rhamnosidases Produced under Solid State Fermentation by Few Aspergillus Strains

The production of α-L-rhamnosidase from Aspergillus ochraceous MTCC -1810, A. wentii MTCC- 1901, A. sydowii MTCC- 635, A. foetidus MTCC-508 under solid- state fermentation using easily available agro- industrial residues such as corn cob, rice bran, sugarcane bagasse, wheat bran and citrus peel as substrate. Among these, sugarcane bagasse in combination with naringin and sucrose were found to be the best substrate. The α-L-rhamnosidase production was highest after the 4th day of incubation at 30ºC and a substrate to moisture ratio of 1:1 w/v. Supplementation of the medium with 10% naringin caused the maximum production of the enzyme. The temperature optima and pH optima of α-L-rhamnosidases were determined in the range of 50-60ºC and 4.0-5.0 respectively. The α-L-rhamnosidases secreted from the above fungal strains is suitable for the debittering of orange fruit juice.

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

The enzyme α-L-rhamnosidase specifically cleaves terminal rhamnose residues from a wide variety of natural products. This property endows this enzyme with important biotechnological potential as L-rhamnosidase could be employed in a variety of applications, including removing bitterness from citrus fruit juices, improving the aroma of wines and converting clinically important steroids. This work optimized α-L-rhamnosidase solid-state fermentation production from Aspergillus niger 426 using statistical methods. Firstly, a statistical mixture-design with three components to determine the best ratio of nutrients for enzyme production was carried out. The optimal conditions consisted of growing the fungi in media containing 0.14 g of cane sugar bagasse, 1.25 g of soybean hulls and 3.05 g of rice straw; these conditions achieved a maximum α-L-rhamnosidase activity of 1.92 U / mL. Next, a 3² Box-Behnken design to optimize culture moisture levels and nutrient solution pH values for enzyme production was carried out. α-L-rhamnosidase activity increased to 3.02 U / mL when medium moisture was 75.5% and pH value of 4.0.