Sea sludge, which is sediment of fish excrement and sewage on the sea bottom, continues to be a serious environmental problem. It has the potential to cause eutrophication and red tide, resulting in the death of shellfish and leading to an offensive odor. Soil taken from a mangrove swamp was added to sea sludge, which promoted an initial fermentation of the sludge components. This article reports on the isolation of a bacterium from mangrove soil that is involved in that fermentation. Three bacteria were isolated on a marine agar plate after incubating for 12 h at 60 degreesC. One of these bacteria fermented sea sludge. 16S rDNA of this bacterium was sequenced, and it had a high homology with that of Bacillus fumarioli LMG17489(T) (AJ250056).