Isolation and characterization of a fucoidan-degrading marine bacterial strain and its fucoidanase

摘要

A marine bacterial strain that degraded fucoidan from Kjellmaniella crassifolia (class Phaeophyceae, order Laminariales, family Laminariaceae) was isolated in our laboratory. The strain was gram-negative, ubiquinone 8 was the predominant respiratory quinone, and the GC-content of its genomic DNA was 36%. The cells of the strain were rod-shaped (2.0 mum long x 1.0 mum wide), and each cell was motile by means of one polar flagellum. Phylogenetic analysis of its 16S ribosomal DNA sequence indicated that it was a member of the family Alteromonadaceae. It produced a type of extracellular fucoidanase, an endosulfated fucan-digesting enzyme. The enzyme was purified with 3500-fold purity at 12.0% yield. Optimum conditions for the enzyme reaction were approximately pH 6.5 to 8.0 and temperature 30degrees to 35degreesC. The enzyme was activated by calcium ions, and maximum activity was observed in the presence of greater than 30 mM calcium ion.