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Background: Marine benthic prokaryotic communities play crucial roles in material recycling within coastal environments, including coral reefs. Coastal sedimentary microbiomes are particularly important as potential reservoirs of symbiotic, beneficial, and pathogenic bacteria in coral reef environments, and therefore presumably play a core role in local ecosystem functioning. However, there is a lack of studies comparing different environments with multiple sites on the island scale, particularly studies focusing on prokaryotic communities, as previous investigations have focused mainly on a single site or on specific environmental conditions. In our study, we collected coastal sediments from seven sites around Okinawa Island, Japan, including three different benthic types; sandy bottoms, seagrass meadows, and hard substratum with living scleractinian corals. We then used metabarcoding to identify prokaryotic compositions and estimate enzymes encoded by genes to infer their functions. Results: The results showed that the three substrata had significantly different prokaryotic compositions. Seagrass meadow sites exhibited significantly higher prokaryotic alpha-diversity compared to sandy bottom sites. ANCOM analysis revealed that multiple bacterial orders were differentially abundant within each substratum. At coral reef sites, putative disease- and thermal stress-related opportunistic bacteria such as Rhodobacterales, Verrucomicrobiales, and Cytophagales were comparatively abundant, while seagrass meadow sites abundantly harbored Desulfobacterales, Steroidobacterales and Chromatiales, which are common bacterial orders in seagrass meadows. According to our gene-coded enzyme analyses the numbers of differentially abundant enzymes were highest in coral reef sites. Notably, superoxide dismutase, an important enzyme for anti-oxidative stress in coral tissue, was abundant at coral sites. Our results provide a list of prokaryotes to look into in each substrate, and further emphasize the importance of considering the microbiome, especially when focusing on environmental conservation. Conclusion: Our findings prove that prokaryotic metabarcoding is capable of capturing compositional differences and the diversity of microbial communities in three different environments. Furthermore, several taxa were suggested to be differentially more abundant in specific environments, and gene-coded enzymic compositions also showed possible differences in ecological functions. Further study, in combination with field observations and temporal sampling, is key to achieving a better understanding of the interactions between the local microbiome and the surrounding benthic community. [ABSTRACT FROM AUTHOR]

Results demonstrate that most marine bacteria are capable of producing anticyanobacterial substances in the absence of cyanide ion in the culture medium. Data reveal that purified anticyanobacterial substance is a beta-cyano-L-alanine.

Many hyperthermophiles can adapt to near starvation conditions, according to a study of Thermococcus and Thermotoga spp in the Kubiki oil reservoir in Japan. Fault blocks in the reservoir prevented the flow of nutrients, which did not affect Thermococcus concentrations but led to a decrease in Thermotoga cell density.

The sea-floor of an inlet of Kodakara-Jima island, Kagoshima, Japan was studied to determine the number of bacteria present in the sediments. Hot spots are present on the sea floor where as the depth of the sediment increased, the number of hyperthermophilic sulfur-dependent bacteria also increased, but the amino acid and the organic carbon content decreased. The hyperthermophilic bacteria probably use the amino acids for their growth and the areas surrounding the hot spots contained autotrophs which produced the organic matter.

Analysis of three hyperthermophilic sulphur-sensitive heterotrophic archaea, separated from a shallow submarine hydrothermal system, reveals that they grow at 60 to 97 degrees Celsius on proteinaceous mixtures such as Casamino Acids, yeast extract and purified proteins. Isolate KS-1 needs nine amino acids for its development, isolate KS-8 needs Tyr along with the nine amino acids and isolate KS-2 needs Lys along with the nine amino acids.