Oceaniovalibus guishaninsula gen. nov., sp. nov., A Marine Bacterium of the Family Rhodobacteraceae

Unveiling the Bacterial Community across the Stomach, Hepatopancreas, Anterior Intestine, and Posterior Intestine of Pacific Whiteleg Shrimp

The gastrointestinal (GI) tract of shrimp, which is comprised of the stomach, hepatopancreas, and intestine, houses microbial communities that play crucial roles in immune defense, nutrient absorption, and overall health. While the intestine's microbiome has been well-studied, there has been limited research investigating the stomach and hepatopancreas. The present study addresses this gap by profiling the bacterial community in these interconnected GI segments of Pacific whiteleg shrimp. To this end, shrimp samples were collected from a local aquaculture farm in South Korea, and 16S rRNA gene amplicon sequencing was performed. The results revealed significant variations in bacterial diversity and composition among GI segments. The stomach and hepatopancreas exhibited higher Proteobacteria abundance, while the intestine showed a more diverse microbiome, including Cyanobacteria, Actinobacteria, Bacteroidetes, Firmicutes, Chloroflexi, and Verrucomicrobia. Genera such as Oceaniovalibus, Streptococcus, Actibacter, Ilumatobacter, and Litorilinea dominated the intestine, while Salinarimonas, Sphingomonas, and Oceaniovalibus prevailed in the stomach and hepatopancreas. It is particularly notable that Salinarimonas, which is associated with nitrate reduction and pollutant degradation, was prominent in the hepatopancreas. Overall, this study provides insights into the microbial ecology of the Pacific whiteleg shrimp's GI tract, thus enhancing our understanding of shrimp health with the aim of supporting sustainable aquaculture practices.

Halocynthiibacter arcticus sp. nov., isolated from Arctic marine sediment

A Gram-staining-negative, oxidase- and catalase-positive, non-motile, aerobic and rod-shaped bacterium producing white colonies, PAMC 20958^T, was isolated from a marine sediment of the Arctic. PAMC 20958^T grew at 10-27 °C (optimally at 21 °C), at pH 5.5-9.5 (optimally at pH 7.0-7.5) and in the presence of 0.5-7.5 % (w/v) (optimally at 2.0 %) NaCl. PAMC 20958^T showed 97.5 % 16S rRNA gene sequence similarity with Halocynthiibacter namhaensis KCTC 32362^T and formed a robust phylogenetic clade with this species. The average nucleotide identity value between strain PAMC 20958^T and H. namhaensis KCTC 32362^T was 79.7 % and the genome-to-genome distance was 13.0 % on average. The genomic DNA G+C content calculated from the genome sequence was 53.2 mol%. The major fatty acids were C_18 : 1ω7c and/or C_18 : 1ω6c. The major respiratory isoprenoid quinone was ubiquinone-10 (Q-10) and major polar lipids were phosphatidylcholine, phosphatidylglycerol, an unidentified aminolipid and two unidentified lipids. On the basis of phylogenetic analysis and genotypic and phenotypic data obtained in this study, it is concluded that strain PAMC 20958^T ( = KCTC 42129^T = JCM 30530^T) represents the type strain of a novel species of the genus Halocynthiibacter, for which the name Halocynthiibacter arcticus sp. nov. is proposed.

Draft genome sequence of Oceaniovalibus guishaninsula JLT2003T

Oceaniovalibus guishaninsula, as a representative of a new genus within the family Rhodobacteraceae, was isolated from surface seawater that was sulfidic. Here, we present the draft genome sequence of the type strain, JLT2003(T).