The regulatory mechanisms of α-L-rhamnosidase synthesis from aspergillus aculeatus and improving the medium for α-L-rhamnosidase production using solid-state fermentation

In this study, the activity of α-L-rhamnosidase was detected by HPLC, the regulatory effects of glucose, nitrogen source and growth factors on the induction of α-L-rhamnosidase were investigated, and the medium was improved for the production of this enzyme from Aspergillus aculeatus JMUdb058 by solid-state fermentation. The results showed that glucose had strong metabolic inhibitory effect on the induction of α-L-rhamnosidase from A. aculeatus. The addition of nitrogen source significantly enhanced the production of α-L-rhamnosidase. Furthermore, in comparison to ammonium sulfate, the addition of organic nitrogen source soybean meal showed a lower activity of α-L-rhamnosidase, which was revealed in light of it contained large amount of starch that inhibited the induction of the enzyme. Among the inorganic nitrogen sources tested, diammonium hydrogen phosphate had the most effectiveness in α-L-rhamnosidase synthesis. The production of α-L-rhamnosidase could further increase by the addition of some growth factors that enriched in amino acids. The solid-state fermentation of an improved medium that consisted of pomelo peel powder (5 g), diammonium hydrogen phosphate (0.5 g), yeast extract (0.075 g) and water (5 mL) showed an α-L-rhamnosidase activity of 10.60 IU/gds, which increased by 84.67% and 1.5 times in comparison with the initial medium and the most effective process reported by other researcher's, respectively. This paper illustrated the regulatory mechanisms of glucose, nitrogen source and growth factor on the synthesis of α-L-rhamnosidase, by which the production of α-L-rhamnosidase was, increased significantly. These results provide a practical technique for the production of α-L-rhamnosidase. ©, 2015, Chinese Institute of Food Science and Technology. All right reserved.