Elucidation of degrading pattern and substrate recognition of a novel bifunctional alginate lyase from sp. NJ-04 and its use for preparation alginate oligosaccharides.

BACKGROUND

The alginate oligosaccharides have been widely used in agriculture, medicine, and food industries due to their versatile physiological functions such as antioxidant, anticoagulant, and antineoplastic activities. The bifunctional alginate lyases can degrade the alginate polysaccharide more efficiently into alginate oligosaccharides. Therefore, it is crucial to discover new bifunctional alginate lyase for alginate oligosaccharide production.

RESULTS

Herein, a novel bifunctional alginate lyase FsAlgB was cloned and identified from deep-sea bacterium sp. NJ-04, which exhibited broad substrate specificity and the highest activity (1760.8 U/mg) at pH 8.0 and 40 °C. Furthermore, the values of FsAlgB towards polyG (0.69 mM) and polyMG (0.92 mM) were lower than that towards sodium alginate (1.28 mM) and polyM (2.06 mM). Recombinant FsAlgB was further characterized as an endolytic alginate lyase, and it can recognize the tetrasaccharide as the minimal substrate and cleave the glycosidic bonds between the subsites of - 3 and + 1.

CONCLUSION

This study provided extended insights into the substrate recognition and degrading pattern of alginate lyases with broad substrate specificity.