Isolation and characterization of alginate-degrading bacteria for disposal of seaweed wastes

Isolation of novel alginate degrading bacteria for the disposal of seaweed waste in composting process.

Decomposition of alginate polymers was checked by the 3,5-dinitrosalicylic acid (DNS) method for reducing sugar, and absorbance at 235 nm for unsaturated sugar. A bacterium A7 was isolated from wakame compost and confirmed to belong to the genus Gracilibacillus by partial 16S rDNA analysis. The optimum condition for the growth of A7 in a medium containing 5 g l(-1) of sodium alginate is as follows: pH, 8.5-9.5; NaCl, 0.5 mol l(-1); temperature, 30 degrees C and polypeptone as nutrient content, 2-5 g l(-1). In a laboratory-scale composting experiment, the alginate content in wakame compost decreased to 14.3% after 72 h of composting from an initial value of 36%, indicating the effectiveness of alginate decomposition of A7 in wakame composting.

The bacterium A7 was found to be alginate lyase-producing in genus Gracilibacillus and effective in degrading alginate to oligosaccharides in wakame during composting process.

Development of new methods for the disposal of marine wastes and production of functional products.