Purification and characterization of an alkaliphilic alginate lyase AlgMytC from Saccharophagus sp. Myt-1

In a previous study, we isolated and reported a second species of the Saccharophagus genus, Saccharophagus sp. strain Myt-1. In the present study, an alginate lyase gene (algMytC) from the genomic DNA of Myt-1 was cloned and characterized. The DNA sequence fragment obtained contained an open reading frame of 1,032 bp that encoded a protein of 343 amino acids with an estimated molecular mass of 37.6 kDa and a pI of 6.60. The deduced protein, AlgMytC, had the conserved amino acid sequences (RTELREM, QIH, YFKAGVYNQ) of the polysaccharide lyase family 7. A BLAST homology search indicated that AlgMytC shared an amino acid sequence identity of 95.9% with alg7A of S. degradans 2-40. The cloned and purified AlgMytC protein showed optimal activity at 40°C, and retained more than 90% of its total activity even after treatment at 25°C for 24 h. AlgMytC was very alkaliphilic with an optimal pH of 9.0, and more than 90% of its activity was retained in the pH range 8.5-10.0. Moreover, AlgMytC was stable over a wide pH range. The activity of AlgMytC was also stable in the presence of various detergents.