Photosynthetic bacterium (PSB) was isolated from sediment samples of Yamagawa Bay, Kagoshima, Japan. Phylogenetic analysis results of PSB isolate were closely related to Rhodobacter sphaeroides, purple non-sulfur photosynthetic bacteria (PNSB) . Pink-colored smooth edges of single bacterial colonies were observed after 3-5 days of incubation period on Basic I medium agar plates. Rhodobacter sphaeroides microscopic examination showed a short rod cell (1-2 µm length) with round ends. Sediment and water samples used for ciliates cultivation were collected from Kuwano-ura Bay, Koshiki Island, Japan. Ciliates were cultivated using fish meal with radish leaves medium (MI) , with sediment into MI (MII) and algae media (MIII) . The use of the algae media (MIII) in cultivation mixture produced the highest total number of ciliates. Big size ciliates were identified as Euplotes minuta and Cyclidium varibonneti, while small size was identified as Micrometopion nutans, based on PCR-DGGE. When ciliates were cultured with the PSB isolate, Rhodobacter sphaeroides as a feed, ciliates grow to 2,081 individual ml -1 72 hrs later. These findings indicate that PNSB can be used to promote ciliates growth.

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We examined the effectiveness of cocopeat and rice hull powder obtained from agricultural wastes as biocarriers for an oil-degrading bacterial consortium. Scanning electron microscopy revealed colonization and strong attachment of bacterial cells on the surface of both carriers. Results of a 60-day in vitro seawater bioremediation trial showed significant oil reduction and high cultivable bacterial counts in treatments augmented with the carrier-attached bacterial consortia compared to treatments supplemented with the same consortium in free living and encapsulated forms. Significant degradations in both aliphatic and aromatic fractions were obtained in treatments augmented with carrier-immobilized consortia. The developed immobilized cells showed sustained activities and viabilities during storage for six months. Results of this study demonstrated that inexpensive waste materials can be utilized as biocarriers of an oil-degrading consortium and that immobilization on biocarriers can enhance the bioremediation of oil-contaminated seawater.

The physicochemical properties and bacterial community in sediments of Lake Shiraishi, a lake with brackish water, were characterized to elucidate the influence of oyster farming and seawater and freshwater inflow. Physicochemical analyses suggested the marine origin of the sediment at the mouth of the lake, while higher organic matter load and the resultant anaerobic, reductive condition of the sediments of the inner part were observed. The bacterial community in the sediments reflects these sediment environments: the bacterial community in the vicinities of oyster farms included sulfate-reducing bacteria (SRB) , although sulfur-oxidizing bacteria (SOB) were found at all the sampling sites. In addition, similarity of the band profiles obtained with 16S ribosomal RNA gene (16S rDNA) -denaturing gradient gel electrophoresis (DGGE) decreased in proportion to the distance from the mouth of the lake to the oyster farms in the inner part. This study was able to characterize the microbial community shift in brackish lake sediments with an oyster aquaculture system through the molecular fingerprinting technique, DGGE, in relation to their physicochemical characteristics.

Marine sediments at intensive fish farming sites in Bolinao‐Anda, northwestern Philippines, are characterized by strong oxygen depletion and the widespread predominance of sulphidic conditions precluding macrobenthic infauna. In less affected areas, however, small macrobenthos (Spionide polychaetes) was present. Experimental sediment mesocosms containing burrowing polychaetes were set up to investigate the possible links between macrofaunal bioturbation of the sediment and its proteolytic capacity to recycle protein‐rich fish farming waste. Relative to polychaete‐free sediment, the addition of small Spionide polychaetes had no significant effect on the proteolytic capacity but caused an increase in the redox potential. On the other hand, the addition of large Eunicide polychaetes caused an increase in both the proteolytic capacity and the redox potential. The deposition of commercial fish feed particles increased the proteolytic activities but decreased the redox potential particularly at a higher deposition rate (250 g m−2 day−1). Accumulation of hydrogen sulphide increased at deposition rates above 83 g m−2 day−1 and limited the survival of large polychaetes.