Marine Actinobacteria – Producers of Enzymes with α-L-Rhamnosidase

Abstract

In recent years researchers have attracted their attention to such glycosidases as α-L-rhamnosidase (α-L-rhamnoside-rhamnohydrolase – EC 3.2.1.40). The substrates of their action are widespread in the plant world glycosides such as naringin, quercetrin, hesperidin, neohesperidin, and rutin, from which α-L-rhamnosidases cleave the terminal unreduced L-rhamnose residues. This specificity of α-L-rhamnosidases can be used in various industries: food – to improve the quality of drinks (reducing bitterness in citrus juices, enhancing the aroma of wines), as well as production of food additives; in the pharmaceutical industry – to improve the biological properties of bioflavonoids, in particular anti-inflammatory. A number of them are characterized by cardio- and radioprotective effects, have antioxidant, cytotoxic, antibacterial, antisclerotic properties, and are used in the complex treatment of coronary heart disease, including angina pectoris. The use of α-L-rhamnosidases in the chemical industry is associated with a reduction in the cost of rhamnose production as well as various plant glycosides and rutinosides. In the literature available to us, no data were found on the producers of α-L-rhamnosidases among the representatives of actinobacteria, which are known to synthesize a wide range of biologically active compounds, including antibiotics and enzymes. Purpose. To study the ability of actinobacteria isolated from water and bottom sediments of the Black Sea, to produce a-L-rhamnosidase, and also to study the properties of the most active producer. Methods. Glycosidase activity was determined by the Romero and Davis methods, protein – by the Lowry method. Results. The study of 12 glycosidase activities in 10 strains of actinobacteria isolated from bottom sediments of the Black Sea indicated that 6 investigated strains showed the ability to synthesize an enzyme with a-L-rhamnosidase and b-D-glucosidase activity. Studies have shown that the highest α-L-rhamnosidase activity (0.14 U/mg protein) was manifested by Acty 5 isolate with an optimum pH of 7.0 and a temperature optimum of 38°C. The enzyme preparation showed substrate specificity both for natural (rutin, naringin, neohesperidin) and synthetic (p-nitrophenyl derivatives of L-rhamnose and D-glucose) substrates. Conclusions. Promising Acty 5 isolate with high a-L-rhamnosidase and low b-Dglucosidase activity was found among marine actinobacteria. Bacteria with two enzymes activity expand the possibilities of their practical use.