The familyErythrobacteraceae, belonging to the orderSphingomonadales, classAlphaproteobacteria, is globally distributed in various environments. Currently, this family consist of seven genera:Altererythrobacter,Croceibacterium,Croceicoccus,Erythrobacter,Erythromicrobium,PorphyrobacterandQipengyuania. As more species are identified, the taxonomic status of the familyErythrobacteraceaeshould be revised at the genomic level because of its polyphyletic nature evident from 16S rRNA gene sequence analysis. Phylogenomic reconstruction based on 288 single-copy orthologous clusters led to the identification of three separate clades. Pairwise comparisons of average nucleotide identity, average amino acid identity (AAI), percentage of conserved protein and evolutionary distance indicated that AAI and evolutionary distance had the highest correlation. Thresholds for genera boundaries were proposed as 70 % and 0.4 for AAI and evolutionary distance, respectively. Based on the phylo-genomic and genomic similarity analysis, the three clades were classified into 16 genera, including 11 novel ones, for which the namesAlteraurantiacibacter,Altericroceibacterium,Alteriqipengyuania,Alteripontixanthobacter,Aurantiacibacter,Paraurantiacibacter,Parerythrobacter,Parapontixanthobacter,Pelagerythrobacter,TsuneonellaandPontixanthobacterare proposed. We reclassified all species ofErythromicrobiumandPorphyrobacteras species ofErythrobacter. This study is the first genomic-based study of the familyErythrobacteraceae, and will contribute to further insights into the evolution of this family.

A Gram-stain-negative, rod-shaped and aerobic bacterial strain, named Ery12^T, was isolated from the overlying water of the Lau Basin in the Southwest Pacific Ocean. Strain Ery12^T showed high 16S rRNA gene sequences similarity to Tsuneonella flava MS1-4^T (99.9 %), T. mangrovi MCCC 1K03311^T (98.1 %), Altererythrobacter ishigakiensis NBRC 107699^T (97.3 %) and exhibited ≤97.0 % sequence similarity with other type strains of species with validly published names. Growth was observed in media with 0–10.0 % NaCl (optimum 0–1.0 %, w/v), pH 5.0–9.5 (optimum 6.0–7.0) and 10–42 °C (optimum 30–37 °C). The predominant respiratory quinone was ubiquinone 10 (Q-10). The major cellular fatty acid was summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c). The major polar lipids were sphingoglycolipid, phosphatidyglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, three unidentified glycolipids, one unidentified aminoglycolipid and one unidentified lipid. The DNA G+C content was 60.8 %. The ANI and in silico DDH values between strain Ery12^T and the type strains of its closely related species were 71.0- 91.8 % and 19.5- 44.6 %, respectively. According to the phenotypic, chemotaxonomic, phylogenetic and genomic data, strain Ery12^T represents a novel species of the genus Tsuneonella , for which the name Tsuneonella suprasediminis is proposed. The type strain is Ery12^T (=CGMCC 1.16500 ^T=MCCC 1A04421^T=KCTC 62388^T). We further propose to reclassify Altererythrobacter rhizovicinus and Altererythrobacter spongiae as Pelagerythrobacter rhizovicinus comb. nov. and Altericroceibacterium spongiae comb. nov., respectively.

In situ fixation of deep-sea nucleic acids remains challenging, as conventional sampling often causes degradation due to abrupt environmental changes. This study developed a novel deep-sea nucleic acid preservation structure based on the Tesla valve principle, comparing it with traditional straight-tube structure. Experimental and CFD simulation results showed that the Tesla-valve structure significantly reduced fixative consumption under the same inlet velocity. At an inlet velocity of 0.2 m/s with a chamber fixative mass fraction of 87.2%, the Tesla-valve structure reduced fixative use by 48.9%. The fixative consumption decreases to minimum at 0.4 m/s in Tesla-value structure. Moreover, we investigated the effects of annular baffle quantity, baffle inclination angle, and central aperture diameter on fixative consumption across varying flow regimes using a numerical simulation method. Results indicated that the number of baffles exerted a significant influence on fixative consumption, with reduced baffle numbers correlating with increased consumption across all flow velocities. Baffle inclination angle and central aperture diameter demonstrated negligible effects on consumption metrics. This work provides an efficient structural design for deep-sea nucleic acid preservation, providing technical support for maintaining nucleic acid integrity during abyssal biological investigations.

Investigations into deep-sea ecosystems are essential for elucidating the origins of life on Earth. Nevertheless, constraints in marine biotechnology have limited our understanding of biological processes occurring in these environments. In this study, we developed and evaluated an in situ cultivation system specifically designed for deep-sea environments. This system enables continuous induction cultivation directly on the seabed and facilitates comprehensive monitoring of the entire cultivation process via an imaging technique. The system is composed of three distinct modules: a cultivation and observation module, a methane slow-release module, and a power management module. This system enables controlled, slow release of energy and materials, allowing for the cultivation and sampling of communities on the seafloor, and supports long-term sequential monitoring through imaging. Through three deployment trials, we successfully established an artificial methane-driven deep-sea ecosystem on the seafloor of the South China Sea. Furthermore, by modifying the types of energy and materials supplied, the system can be adapted to address diverse scientific objectives, offering a robust tool for advancing research on deep-sea life.