Members of the bacterial genus Thalassotalea have been isolated recently from various marine environments, including marine invertebrates. A metagenomic study of the Deepwater Horizon oil plume has identified genes involved in aromatic hydrocarbon degradation in the Thalassotalea genome, shedding light on its potential role in the degradation of crude oils. However, the genomic traits of the genus are not well-characterized, despite the ability of the species to degrade complex natural compounds, such as agar, gelatin, chitin, or starch. Here, we obtained a complete genome of a new member of the genus, designated PS06, isolated from marine sediments containing dead marine benthic macroalgae. Unexpectedly, strain PS06 was unable to grow using most carbohydrates as sole carbon sources, which is consistent with the finding of few ABC transporters in the PS06 genome. A comparative analysis of 12 Thalassotalea genomes provided insights into their metabolic potential (e.g., microaerobic respiration and carbohydrate utilization) and evolutionary stability [including a low abundance of clustered regularly interspaced short palindromic repeats (CRISPR) loci and prophages]. The diversity and frequency of genes encoding extracellular enzymes for carbohydrate metabolism in the 12 genomes suggest that members of Thalassotalea contribute to nutrient cycling by the redistribution of dissolved organic matter in marine environments. Our study improves our understanding of the ecological and genomic properties of the genus Thalassotalea.

Plant endophyte and epiphyte communities cooperatively interact with their host plants and play crucial roles in sustaining plant fitness. In Korea, a variety of studies have been conducted to elucidate the reasons for the declining population of the endangered Korean fir (Abies koreana), but the relationship between microbiota and the healthy condition of trees remains unclear. Here, we conducted bacterial 16S rRNA gene and fungal ITS sequence analyses to dissect the composition of endophytic and epiphytic microbiota in both live and dead trees located in the same Mt. Jiri habitat. In the live trees, the bacterial class Armatimonadia and the lichenized fungi groups were significantly dominant, whereas many bacterial and fungal taxa mainly found in rotten wood were enriched in the dead trees. Functional prediction of the microbial communities in live trees suggested the possibility that bacterial endophytes and epiphytes play a role in inorganic nutrient metabolism and fungal endophytes and epiphytes produce biologically active secondary metabolites, thereby contributing to the healthy condition of Korean fir trees. The ecological function of endophytes and epiphytes in dead trees was predicted to be involved in the decomposition of wood for nutrient recycling. Our analyses revealed a distinct difference in microbial communities depending on the health condition of Korean fir trees. The results from this study would be useful for understanding the ecological function of endophytic and epiphytic microorganisms to conserve and manage this endangered species from ecologically vulnerable environments.

A Gram-stain-negative, rod-shaped, and facultatively anaerobic bacterium named strain GJ3^T was isolated from coastal sediment of Jeju Island, South Korea. Catalase and oxidase activity were detected in the cell of strain GJ3^T, as well as white pigmented colony and motility with polar flagellum. The cell grew optimally at 30 °C, pH 7.0, in the presence of 4% (w/v) sodium chloride. Phylogenetic analysis using the 16S rRNA gene sequence indicated that strain GJ3^T was classified to the genus Photobacterium, with high sequence similarity to Photobacterium galatheae S2753^T (98.30%), Photobacterium halotolerans MACL01^T (97.90%), and Photobacterium panuliri LBS5^T (96.55%). Strain GJ3^T possessed only ubiquinone-8 (Q-8) as a respiratory quinone and summed feature 8 as the major fatty acid (38.18%). Additionally, the dominant polar lipids phosphatidylglycerol and phosphatidylethanolamine were identified. The complete genome size and G + C content of strain GJ3^T was estimated to be 3,603,274 bp in length and 50.70%, respectively. Polyphasic approach and genomic analyses (e.g., ANI and digital DDH) revealed that strain GJ3^T (=KCTC 72816^T = KMM 6822^T) represented a novel species within the genus Photobacterium, and the name Photobacterium halophilum sp. nov., is proposed for this novel bacterium.