Microbial degradation of mussels removed from the surface of marine structures

摘要

After being crushed, a net weight 218 kg of mussels was reduced to 120.5 kg by discharge of seawater from the shells. The sample containing some of broken shells was applied to the degradation by Bacillus sp. The initial weight of 120.5 kg was reduced to 82.5 kg after 76 h of microbial degradation. Concentrations of the produced carbon dioxide and ammonia showed peak values of 15,000 and 720 ppm after 12.5 and 58 h, respectively. At 12.5 h, temperature in the sample reached to 65 degrees Celsius by the fermentation temperature. The ratio of total amounts of carbon and nitrogen, C/N ratio, was 22.6 after 76 h. Some of the heavy metals and toxic chemical compounds, which cause environmental pollution, were analyzed in the sample for the recycle of compost. The concentrations of such compounds detected were much lower than those recommended by the Japanese Ministry of the Environment. Therefore, the recycling of compost seems to be legal and possible. The strain used in this experiment was identified as Bacillus subtilis subsp. subtilis based on the biochemical and physiological properties as well as the homology analysis for the partial sequences of 16S rDNA.