Marine Pollution Control by Seaweed Planting and Composting
12 May, 2008 12:05 pm
According to a new study by researchers in China and Japan, we found that marine bacteria were helpful in enhancing composting process of wakame, a kind of seaweed generally existed in the coastal area of the sea. The discovery was reported in the International Journal of Biotechnology, an Inderscience publication.
We isolated efficient bacteria with high ability of degradation from seaweed as well as marine environments and compared their effectiveness to make up wakame compost. A novel bacterium AW4 was found and identified as genus of Halomonas by partial 16S rDNA analysis.
The researchers point out that strain AW4 may initialize the composting process of Wakame within short time and grow well even at high salt (sodium chloride) concentrations, where the organic components of seaweed were significantly degraded within a week. In particular, the alginate, which is a kind of special polysaccharide and included as main component in wakame, can be decomposed to oligosaccharide during this process and the degraded material becomes to promote the root growth of plant. This is the first report that the wakame compost was proven to be a good source of agricultural fertilizer and it is also important for the recycling of organic pollutant in the coastal area.
Marine pollution is now one of the serious environmental problems in the coastal and closed sea areas. Thus, the bioremediation of nutrients in the seawater becomes increasingly important. Planting of seaweeds is one of the good choice to solve this kind of problem. The research group has conducted bioremediation experiment by using brown seaweed, Undaria pinnatifida or called wakame, for more than 10 years. However, the cultured wakame may contain some contaminants such as heavy metals and nutrients so that it must be treated as a kind of wastes. They pointed out that the disposal of wakame by composting process is supposed to be effective not only on the degradation of wakame but also on the recycling of organic substances containing C, N and P.
We have conducted many researches on the disposal of organic waste through biological approaches. In their previous studies, they have successfully isolated bacterium, Bacillus sp. HR6 for disposal of bean curd refuse.
Caution should be also made during the application of the wakame waste, since pollutants in the wakame may be transferred to the soil. Further research is now conducted for the safer application of the wakame compost.
"Disposal of seaweed wakame (Undaria pinnatifida) in composting process by marine bacterium Halomonas sp. AW4", Jingchun Tang, Yutang Xiao, Akinobu Oshima, Hiroshi Kawai, Shinichi Nagata. International Journal of Biotechnology, vol. 10, iss. 1, 2008.