Disposal of seaweed wakame (Undaria pinnatifida) in composting process by marine bacterium Halomonas sp. AW4

A novel marine bacterium, identified as Halomonas sp. AW4 by partial 16S rDNA analysis, was isolated from the seaweeds in Awaji Island, Japan. Strain AW4 grew well even in the wide NaCl concentration ranges of 0-3 mol/L, where it showed an optimal growth in the presence of 0.5 mol/L NaCl. The organic components were reduced to 73.6% of initial dry weight after 168 h of composting by inoculation of AW4. The microbial community structure became complex after 72 h of composting. The initial content of alginate was 35.6%, which decreased to 15.6% after 168 h of composting. The decomposition of alginate mainly occurred at the late stage of composting, suggesting that the microbial community consisting of various types of microorganisms is effective in degrading alginate. The germination of plant Brassica campestris L. indicated the promotion effect of composted wakame.