Studies on agar degrading Salegentibacter sp. and characterization of its agarase.

The phenotypic and agar degrading features of an unidentified marine bacteria was investigated. The strain was Gram-negative, obligatory aerobic and non motile. On the basis of several morphological features and a phylogenetic analysis of the genes coding for the 16S rDNA, this strain was identified as Salegentibacter sp. On solid agar medium, this isolate produced extracellular agarase which causes agar liquefaction around the colonies. An extracellular agarase was purified by ammonium sulfate precipitation, gel filtration and ion-exchange chromatography on DEAE-cellulose. The purified protein migrated as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it had a molecular weight of 28 kDa. The enzyme exhibited maximal activity at pH 7.5. The kinetic parameters of the enzyme were Km = 3 ± 0.19 mM, Kcat = 160 ± 10 S -1and Kcat / Km = 53 ± 10 S -1.mM -1. The purified agarase may be used for application in protoplast formation of agarophytes which can subsequently be used in algal biotechnology to evolve a superior strain of Gracilaria sp. yielding superior quality agar.