Purification and Characterization of a Novel Alginate Lyase from a Marine Streptomyces Species Isolated from Seaweed

Abstract

Alginate, a natural polysaccharide derived from brown seaweed, is finding multiple applications in biomedicine via its transformation through chemical, physical, and, increasingly, enzymatic processes. In this study a novel alginate lyase, AlyDS44, was purified and characterized from a marine actinobacterium, Streptomyces luridiscabiei, which was isolated from decomposing seaweed. The purified enzyme had a specific activity of 108.6 U/mg, with a molecular weight of 28.6 kDa, and was composed of 260 amino acid residues. AlyDS44 is a bifunctional alginate lyase, active on both polyguluronate and polymannuronate, though it preferentially degrades polyguluronate. The optimal pH of this enzyme is 8.5 and the optimal temperature is 45 °C. It is a salt-tolerant alginate lyase with an optimal activity at 0.6 M NaCl. Metal ions Mn2+, Co2+, and Fe2+ increased the alginate degrading activity, but it was inhibited in the presence of Zn2+ and Cu2+. The highly conserved regions of its amino acid sequences indicated that AlyDS44 belongs to the polysaccharide lyase family 7. The main breakdown products of the enzyme on alginate were disaccharides, trisaccharides, and tetrasaccharides, which demonstrated that this enzyme acted as an endo-type alginate lyase. AlyDS44 is a novel enzyme, with the potential for efficient production of alginate oligosaccharides with low degrees of polymerization.

Alginate Lyases from Marine Bacteria: An Enzyme Ocean for Sustainable Future

“…It has been disclosed that depolymerized low DP alginate prepared through an enzymatic converter possesses various kinds of biological activities [ 63 , 99 ]. Nguyen et al prepared a series of AOSs with the potential for efficient production of low DP alginate oligosaccharides by using a new marine actinobacterium-produced alginate lyase AlyDS44 Streptomyces luridiscabiei [ 100 ]. In addition, Aly-IV from Vibrio.…”

“…SM0524 [ 93 ], Pseudoalteromonas carrageenovora ASY5 [ 108 ], Agarivorans sp. L11 [ 109 ], and Streptomyces luridiscabiei [ 100 ]. Moreover, bifunctional lyases possess different degradation activities toward different substrates.…”

“…Higher optimal temperatures were found on several alginate lyases produced by Cobetia sp. NAP1 (AlgC-PL7) [ 107 ], Streptomyces luridiscabiei (AlyDS44) [ 100 ], Vibrio sp. W2 (Alyw202 and Alyw203) [ 105 , 119 ], which had the optimum working temperature of 45 °C.…”

“…Ca 2+ and Mg 2+ are stimulatory cofactors for regulating the enzyme activity of alginate lyases [ 60 ]. As shown in Table 2 , in the presence of Mn 2+ and Co 2+ , the alginate degradation activity of AlyDS44 increased by 242% and 219%, respectively, while Ca 2+ and Mg 2+ showed no effect on the AlyDS44 activities; however, Zn 2+ , Cu 2+ , and Fe 3+ exhibited a slight or moderate enzyme inhibition effect [ 100 ]. For Aly-IV, its activity was significantly inhibited by Ba 2+ , Al 3+ , Ni 2+ , Zn 2+ , and Pb 2+ (1 mM) but was promoted by Ca 2+ (1 mM), K + (5 mM) and Mg 2+ (10 mM) [ 96 ].…”

Conversion of Fishery Waste to Proteases by Streptomyces speibonae and Their Application in Antioxidant Preparation

“…Streptomyces is a genus of soil actinomycetes that is a worthy source of various bioactive compounds [16]. As enzyme sources, many Streptomyces strains have been discovered to produce various extracellular enzymes such as chitinase, xylanase, lipase, cellulase, pectinase, amylase, and protease [17][18][19][20][21][22]. Streptomyces enzymes are well known for their outstanding catalytic properties, such as thermostability and broad pH range, making them suitable for use in different industrial sections [17].…”