We report the complete genome sequence of Pseudalkalibacillus sp. Hm43 isolated from marine sponge Haliclona caerulea in Guangxi coral reef, China. The genome consists of a circular chromosome (3,739,586 bp; guanine-cytosine [GC] content: 43.4%), including three GH18 chitinase genes. Strain Hm43 exhibits exochitinase and endochitinase activities.

A Gram-stain-negative, aerobic, and rod-shaped bacterium, designated H14T, was isolated from a tidal flat in Zhoushan, Zhejiang Province, China. Colonies of strain H14T were yellow, round, smooth and convex after cultivating on marine agar at 37 ℃ for 72 h. Cells were catalase-positive and oxidase-negative. Growth occurred at 16–40 ℃ (optimum, 37 ℃), pH 5.0–8.5 (optimum, pH 6.5) and with 0.5–10.0

Estuarine ecosystems face intense anthropogenic pressures, yet systematic research on how domestic wastewater influences the dissolved organic carbon (DOC) pool via microbial community regulation remains limited. In this study, we conducted a microcosm experiment simulating wastewater input into the Qiantang River and integrated multi-omics (16S rRNA sequencing, metagenomics, metatranscriptomics, and FT-ICR MS) to elucidate the mechanism. Results showed that: (1) Wastewater input increased initial DOC and changed its degradation pattern: slower decay but higher removal. (2) Compared to the control, the wastewater-amended group exhibited a decreased fluorescence intensity contribution of carboxyl-rich alicyclic molecule (CRAM)-like compounds, indicating reduced chemical stability of recalcitrant DOC (RDOC). (3) Wastewater drove directional microbial succession from catabolic-dominant taxa (e.g., Comamonas, Citrobacter) to anabolic-dominant taxa (e.g., Reyranella), shifting metabolism from pollutant degradation to endogenous synthesis, thereby lowering the system’s efficiency in forming stable RDOC. (4) Multi-omics revealed a “stimulation-balance” functional response: early activation of xenobiotic degradation and signal transduction (day 2), followed by a shift to anabolic metabolism (day 28). This functional transition, driven by microbial succession, ultimately reduced RDOC stability. Our findings reveal that wastewater reshapes the microbial carbon pump, providing a theoretical basis for assessing estuarine carbon sink responses to pollution control measures.

Seasonal changes drive rhythmic biological cycles across ecosystems, including unvegetated tidal flats, where strong temperature shifts shape microbial activity, yet long-term microbial rhythmicity remains unexplored. Here we show, using a two-year monthly dataset comprising 864 amplicons and 288 metagenomes from mudflats and sandflats in eastern China, that microbial communities and functions exhibit clear temporal rhythmicity and spatial heterogeneity, including variation in carbon fixation potential. Rhythmicity and network analyses identify temperature as the primary environmental factor associated with seasonal microbial rhythms, while sediment type and depth modulate their strength. MAG-based and metaproteomic analyses further support sulfur-oxidizing Sulfurovum and Sulfurimonas as primary contributors to strong seasonal fluctuations of rTCA-cycle genes in deeper mudflats. This study addresses a knowledge gap regarding long-term microbial rhythmicity in unvegetated tidal flats of eastern China. The observed temperature–microbe associations highlight the potential role of microbiomes in coastal carbon cycling; however, their generality at the global scale requires further validation. Seasonal temperature changes shape microbial community patterns and carbon fixing gene fluctuations in tidal flats, and sulfurovum and sulfurimonas strains are primary contributors of carbon fixing gene fluctuations, based on seasonal microbial rhythmicity analysis in unvegetated tidal flats using a two-year monthly multi-omics dataset.

Tidal flats are critical transitional ecosystems in which microbial communities drive essential biogeochemical processes while adapting to strong environmental fluctuations. However, the mechanisms by which these communities maintain functional stability in highly dynamic tidal-flat environments remain poorly understood. In this study, we analyzed 276 tidal-flat samples from 92 coastal sites along the Chinese coastline to investigate the relationship between microbial diversity and community function. Our results revealed significant spatial variability in microbial communities across different regions of the Chinese coastline. Although latitude and geographic distance had detectable effects, the community turnover was governed primarily by environmental filtering and stochastic assembly, with temperature emerging as a key environmental driver. Despite the great variation in species diversity, the relatively similar functions of microbial communities across different regions were observed, indicating the existence of functional redundancy. Using a novel framework to quantify how the redundancy varies across microbial functions and communities, we illuminated the redundancy order of major biogeochemical functions in tidal flats as carbon > sulfur > nitrogen metabolism. We also identified three distinct redundancy patterns: high-, low-, and latitude-associated redundancy. By identifying the contributor composition underlying each function, we further revealed that the functional redundancy in tidal-flat ecosystems was shaped by the distribution of functional genes across microbial lineages, and that shifts in the balance between generalists and specialists helped explain the observed diversity of redundancy patterns. This study provides a quantitative framework for delineating microbial functional redundancy and its underlying contributor composition. By applying this framework to tidal flats along the Chinese coastline across four climatic zones, we revealed distinct patterns of functional redundancy and illuminated that a shift in the primary functional contributor would alter the redundancy pattern. These findings underscore the critical role of contributor composition in determining the stability and resilience of tidal-flat microbiomes.

A yellow, Gram-stain-negative, facultatively anaerobic and rod-shaped strain, designated as HB62T, was isolated from seawater in the tidal region of Danzhou, Hainan Island, People's Republic of China. Growth of strain HB62T occurs at 16-40 °C, 0.5-10.0% (w/v) and pH 6.0-9.5 with the optima of 37 °C, 1.5-2.0% (w/v) and pH 6.5-7.0. Strain HB62T could grow anaerobically by using nitrate and sulphate as electron acceptors. The 16S rRNA gene sequence identity analysis showed that strain HB62T shared the highest sequence identity of 98.0% with Salinimicrobium soli CAU 1287T and those of ≤97.9% and ≤94.6% with the rest of Salinimicrobium type strains and other genera type strains, respectively. Phylogenetic trees based on 16S rRNA genes and single-copy orthologous clusters revealed that strain HB62T was stably clustered into the genus Salinimicrobium. Average nucleotide identity and digital DNA-DNA hybridization values of strain HB62T and Salinimicrobium type strains were 72.1-78.2% and 17.8-21.2%, respectively, which were lower than the species delineation thresholds. The sole respiratory quinone was identified as menaquinone-6. Major fatty acids (>10%) are iso-C15:0, iso-C16:0 and summed feature 9 (iso-C17:1  ω9c and/or C16:0 10-methyl). Polar lipids included phosphatidylethanolamine, two unidentified glycolipids, three unidentified lipids and two unidentified aminolipids. Based on the genetic, chemotaxonomic and phenotypic results, strain HB62T is concluded to represent a novel Salinimicrobium species, for which the name Salinimicrobium aquimaris sp. nov. is proposed. The type strain is HB62T (=KCTC 102226T=MCCC 1K08856T).

Mudflats play an important role in coastal carbon cycling. The colonization of diatom-dominated microphytobenthic biofilms and associated heterotrophic microbial communities, affects the biogeochemical cycling in mudflats. Yet, the influence of biofilm colonization on the microbial communities and organic matter profiles in mudflats remains poorly understood. Here, 84 samples were collected in different seasons, locations and depths with/without biofilms in tidal flats of Zhejiang, China, and a multiparametric analysis was performed on environmental factors, microbial communities and dissolved organic matter (DOM) profiles to reveal the multidimensional influence of biofilm colonization on mudflats. The results showed that, compared with surface adjacent bare sediment (surface ABS), biofilms exhibited higher carbon stocks, lower bacterial diversity, and a shift in the dominant community assembly process from dispersal limitation to homogeneous dispersal. The microbial communities in biofilms and related sediments showed a higher abundance of functional genes involved in carbon, nitrogen and sulfur cycling, including carbon fixation and metabolism, leading to high proportion of recalcitrant DOM in the biofilm-related sediments, in which, Pseudomonadota, Bacteroidota, Chloroflexota and Bacillota acted as key functional groups. This study highlights the association between biofilm occurrence, microbial community composition, functional potential, and organic matter characteristics in mudflat sediments, highlighting the potential contribution of biofilms to carbon retention and transformation processes in mudflat ecosystems.

Chemoautotrophs drive carbon fixation in coastal sediments, but most of them remain uncultured with poorly characterized in situ activities. In this study, a cultivation-independent single-cell approach combining Raman spectroscopy with 13C-stable isotope probing was developed to enable direct identification of active chemoautotrophs in coastal sediments using function-specific spectral biomarkers, targeted metagenomic sequencing and pure culture verification. 13C-induced shifts in cytochrome c (749, 1129, 1312, 1589 cm-1) and phenylalanine (1002 cm-1) Raman bands were systematically evaluated and applied as functional biomarkers through investigations of both representative chemoautotrophic strains and environmental samples. The combined analysis of targeted sorting of active chemoautotrophic cells and metagenomic sequencing revealed dominant species and a complete Calvin-Benson-Bassham (CBB) cycle pathway in sulfur-oxidizing guilds. Remarkably, a novel sulfur-oxidizing chemoautotroph, Guyparkeria sp. TX1, which showed ≥99% gene sequence similarity to contigs recovered from sorted-cell metagenomes, was isolated from enrichment cultures. Its significant carbon fixation capacity provided experimental validation for the effectiveness of Raman-based in situ functional screening. This study establishes Raman-based functional biomarkers applicable to chemoautotrophic carbon fixation, enabling in situ mapping of microbial carbon fluxes. By integrating single-cell phenotypic activity with genomic potential, this work advances the mechanistic understanding of sulfur-driven dark carbon fixation, which sustains coastal blue carbon ecosystems as a keystone process.

Bacterial wide genomic GC variation poses numerous interesting scientific questions, which center on the role evolution plays in shaping genome content and the mechanisms that abruptly alter such processes. In this study, eleven Kordiimonas genomes were obtained and processed for comparative genomic, phylogenetic, evolutionary, and statistical analyses. The phylogenomic reconstruction based on single-copy orthologous cluster protein sequences and overall genomic relatedness index calculations showed that the genus Kordiimonas could be separated into GC-rich (56.3 to 59.9%) and -poor (46.2 to 49.6%) groups, and Ca. Kordiimonas sp. UBA4487 should be reclassified to remove it from this genus. Comparisons of amino acid frequencies in the genus also indicated that the GC-rich and -poor groups had several significantly different amino acid usages. Evolutionary analysis revealed that the GC-poor group had significantly higher nonsynonymous and synonymous substitution rates than the GC-rich group did, and evolved from the GC-rich ancestor. Comparative genomics also demonstrated that the GC-rich group encoded more genes related to nitrogen metabolism and transport than the GC-poor group did, leading to ecological niche diversification of the two groups, which could reduce inter-species competition in similar environments. Our study characterized the evolutionary patterns involved in nucleotide substitutions and their trends, as well as metabolic changes at the genus level, which can shed light on the understanding of bacterial microevolution in the future.

A Gram-stain-negative, rod-shaped bacterial strain, designated GZD-96T, characterized by strictly aerobic metabolism, was isolated from tidal flat collected at Sanbei Shoal, Ningbo, China. This strictly aerobic strain formed orange, round, convex colonies on marine agar at 37 °C. It exhibited growth at 10–40 °C (optimum: 37 °C), 0–7

The order Sphingomonadales strains are globally distributed in various biomes and are renowned for their biodegradable and biosynthesis capabilities. At present, it consists of 4 families and 49 genera making it the third largest order within the class Alphaproteobacteria . However, their taxonomy remains complex, especially due to polyphyly in the family Sphingomonadaceae . In this study, we collected 429 Sphingomonadales type strain genomes, reconstructed robust phylogenomic relationships, and proposed delineation thresholds at the genus and family levels based on average amino acid identities (AAI) and evolutionary distances (ED). Based on the maximum-likelihood and Bayesian phylogenomic trees reconstructed by two molecular sets determined by orthologous sequence identity and the Genome Taxonomy Database, the consensus degree values were all higher than 90%, revealing that those phylogenomic trees had similar topological structures. By confirming monophyletic taxa and determining stable nodes, we reclassified the order Sphingomonadales into thirteen families including nine novel ones. AAI calculations indicated that the average intra-family AAI values ranged from 0.62 to 0.84, while inter-family ones were 0.51 to 0.60. ED summaries demonstrated that the average and median intra-family ED values were 0.16 to 0.57, and inter-family ones ranged from 0.50 to 1.22. Comparisons of AAI and ED values calculated by using genomic and phylogenetic analyses supported that those 13 families were significantly separated with p values < 2.2×10 −16 . Thus, it was speculated that the AAI and ED thresholds for distinguishing different families were <0.6 and >0.5, respectively. Additionally, we reclassified 163 species into new genera with their phylogenetic topologies, according to the previous genus AAI and ED boundaries of 0.7 and 0.4. Our study is the first genomic-based study of the order Sphingomonadales and will promote further insights into the evolution of this order.

Nitrate reduction serves as a pivotal process in the global nitrogen cycle, playing a crucial role in natural ecosystems and industrial applications. Although the genus Alteromonas is not traditionally regarded as a nitrate reducer, several Alteromonas strains have recently been found to be capable of doing so. However, the evolutionary trajectory of this capability remains undiscovered. In this study, 32 bacterial strains were isolated and cultivated from the tidal flat sediment in Hangzhou Bay and classified into the classes Cytophagia (n = 2), Alphaproteobacteria (n = 2), Gammaproteobacteria (n = 17), Flavobacteriia (n = 5), and Bacilli (n = 6). One nitrate-reducing strain, designated as CYL-A6T, was identified by polyphasic taxonomy and proposed as a novel Alteromonas species. Genomic analysis reveals that seven Alteromonas genomes encode the dissimilatory nitrate reduction genes narGHI. Evolutionary analysis showed that these three nitrate-reducing genes were present in the early common ancestor of the genus Alteromonas, while gene loss events occurred in the subsequent evolution. With the loss of nitrate-reducing genes in the ancestry nodes, a wide variety of genes related to energy production and conversion, as well as carbohydrate, nucleotide, coenzyme, and inorganic ion metabolism, were gained in those nodes, which enabled Alteromonas members to utilize diverse substrates for increased energy production. This study enhances the understanding of microbial diversity in marine tidal flat sediments, proposes a novel nitrate-reducing species of the genus Alteromonas, and highlights the ecological diversification and ecological niche breadth in the evolution of the microbial metabolic network.

Flavobacteriaceae is the major participant in the degradation of algal polysaccharides. With diverse polysaccharide utilization loci (PULs) and specific carbohydrate-active enzymes (CAZymes), Flavobacteriaceae strains appear to have different abilities in algal polysaccharide degradation and therefore change their roles in the bacterial community. Here, we identified two novel isolates as two novel species of genus Flagellimonas with the names Flagellimonas alginolytica sp. nov. and Flagellimonas cixiensis sp. nov. Furthermore, the comprehensive genomic comparison of 41 Flagellimonas genomes revealed that Flagellimonas strains were diverse in the CAZymes and PUL profiles and exhibited a preference for polysaccharides derived from brown algae. The evolutionary analysis of alginate utilization loci (AUL) in this genus illuminated that the function genes in AULs, that is, PL7 and PL17, were more reliant on the stable inheritance from ancestors associated with gene duplication and loss rather than horizontal gene transfer (HGT) from outside, and the AUL structures exhibited a trend of simplification which resulted in the incidental decrease in alginate degradation ability. This study highlights the important role of vertical inheritance in the evolution of AULs and proves that the discrepancy in AUL structure can arouse phenotypic differences, providing a new perspective on the evolution of AUL and the niche adaptation mechanism of Flavobacteriaceae strains.IMPORTANCEFlavobacteriaceae play an important role in the marine carbon cycle with their noteworthy ability in algal polysaccharides degradation, which is primarily reliant on diverse polysaccharide utilization loci (PULs). Our study highlights the crucial role of vertical inheritance in the evolution of alginate utilization loci (AUL) in Flagellimonas strains and reveals the AUL structural simplification found in Flagellimonas strains that will lead to the reduction of alginate degradation ability. These insights advance understanding of niche adaptation strategy and related evolutionary mechanisms of Flavobacteriaceae strains.

We report the complete genome sequence of Leeuwenhoekiella parthenopeia H156 isolated from tidal flat sediment in Zhejiang, China. The genome consists of a 4.43 Mbp circular chromosome with annotated 331 carbohydrate-active enzymes. It contains 32.5 glycoside hydrolases/Mb, higher than other Leeuwenhoekiella genomes, indicating its potential in carbohydrate polymer degraders.

Sediment burial generated by deep-sea mining is usually lethal to echinoderms, which are ecologically important in marine environments. However, their molecular mechanisms responding to sediment burial are still rarely investigated. In this study, Patiria pectinifera was investigated for sediment burial research to analyze its gene expression variations by using comparative transcriptomes and to probe into shared molecular mechanisms of echinoderms under sediment burial. During sediment burial experiments, dissolved oxygen continuously decreased, which had a significant impact on Patiria pectinifera, which suffered from hypoxic stress. Based on functional annotations of differentially expressed genes (DEGs), its metabolic patterns altered with the upregulated DEGs related to glycolysis and fatty acid degradation and the downregulated ones in the citrate cycle, and its immune responses also varied with the upregulated DEGs of apoptosis and the downregulated ones defending against pathogens. Meanwhile, the peroxisome proliferator-activated receptor signaling pathway and retinoic acid-inducible gene I-like receptor signaling pathway were also upregulated, indicating metabolic and immune changes. Furthermore, combined with functional annotations of twelve echinoderm reference genomes, those DEGs related to lipid metabolism and the immune response were also universally present in the echinoderm genomes. Our study probes into shared molecular mechanisms of echinoderms under sediment burial, which advances our understanding of echinoderms affected by deep-sea mining.

The complete metabolism of carbohydrates, as the most abundant and structurally diverse organic matter on earth, requires the involvement of different carbohydrate-active enzymes (CAZymes). Flavobacteriales and Cytophagales are two groups whose members specialize in polysaccharide metabolism, but research on their polysaccharide metabolic patterns based on the overall CAZymes is scarce. In this study, we analyzed 702 filtered genomes of Flavobacteriales and Cytophagales and obtained 100,445 CAZymes. According to their taxonomic status and living environment, we explored the impact of taxonomic status, isolation source, and environmental condition on their potential polysaccharide metabolic patterns. The results indicated significant differences in the CAZyme composition among different taxonomic statuses or environments. Compared with the Flavobacteriales genomes, the genomes of Cytophagales possess more abundant and diverse CAZymes, but have fewer unique CAZyme families. Genomes from different families vary greatly in terms of CAZyme family diversity and composition, but relatively small divergences were found from families in the same order. Furthermore, our findings indicated that genomes from the marine and tidal flat environments share more similarities in CAZyme family composition and diversity compared with the terrestrial genomes. Extreme environments greatly constrain the types of CAZyme families present, and certain CAZyme families are significantly lower than those in normal environments. Although significant differences were found among genomes from both different taxonomic statuses and environments, the dimensionality reduction and the clustering analysis based on CAZyme composition indicated that evolutionary status is the main factor influencing the polysaccharide metabolic patterns of these strains. The correlations among CAZyme families indicated that the majority of these families are synergistically involved in polysaccharide metabolism. This study provides a comprehensive profile of the CAZymes in Flavobacteriales and Cytophagales, highlighting the role of evolutionary status in shaping the polysaccharide metabolic patterns and the prevalence of synergism among CAZyme families. These findings have implications for understanding microbial carbohydrate metabolism in different environments.

Carotenoids are extensively used in drugs, cosmetics, nutrients, and foods, owing to their antioxidant and anti-inflammatory characteristics. Diverse marine heterotrophic prokaryotes can accumulate carotenoids and become promising alternatives for the advancement of carotenoids production. In this research, 55 strains were isolated and cultivated from tidal flat sediment in Zhoushan and classified into the phyla Pseudomonadota (n = 24), Bacillota (n = 18), Bacteroidota (n = 9), and Actinomycetota (n = 4). Nine of them accumulated carotenoids, and most of them belonged to the families Flavobacteriaceae (n = 4) and Erythrobacteraceae (n = 4). Among those carotenoid-producing strains, one strain, designated as D39T, was proposed as one novel species belonging to the genus Croceibacterium through polyphasic taxonomy approaches. Genomic annotations and carotenoid compound determinations revealed that strain D39T encoded crtEBIYZG genes and mainly accumulated zeaxanthin as major carotenoids. Furthermore, carotenoid biosynthesis pathway in the majority of Croceibacterium strains were identical with that in the strain D39T, implying that Croceibacterium members can be sources of producing zeaxanthin. This study enhances knowledge of microbial biodiversity in tidal flats, proposes a novel carotenoid-producing Croceibacterium species, and elucidates carotenoid biosynthesis pathway in the genus Croceibacterium, which contribute to enriching marine carotenoid-producing strains and promoting a comprehensive insight into genomic contents of them.

A Gram-stain-negative, aerobic, motile with flagella and rod- or ovoid-shaped bacterium, designated GG15(T), was isolated from tidal flat sediment sampled in Zhoushan, Zhejiang Province. Strain GG15(T) grew at 20-40 degrees C (optimum, 30 degrees C), at pH 5.5-9.5 (optimum, pH 7.0-8.0) and with 1.0-10.0 % (w/v) NaCl (optimum, 1.5 %). Colony diameters ranged from 1 to 3 mm within the first week, reaching a maximum of 6-7 mm after 15 days of cultivation. Strain GG15(T) exhibited highest 16S rRNA gene sequence similarity to Microbulbifer taiwanensis CCM 7856(T) (98.1 %), with similarity to other species within the genus Microbulbifer ranging from 97.8 to 93.8 %. Similarity values to other genera were below 93.8 %. Strain GG15(T) exhibited positive activity for beta-glucosidase, trypsin and chymotrypsin, whereas the reference strain showed negative activity. Chemotaxonomic analyses indicated that strain GG15(T) contained Q-8 as the sole respiratory quinone, C-16 : 0 (9.1 %), iso-C-15 : 0 (30.9 %) and iso-C-11 : 0 3-OH (7.2 %) as the predominant fatty acids, and phosphatidylethanolamine, phosphatidylglycerol, three unidentified lipids, four unidentified glycolipids, one unidentified phospholipid, two unidentified aminolipids and two unidentified aminophospholipids as the main polar lipids. The genome of strain GG15(T) was 4 307 641 bp long, comprising 3861 protein-coding genes. The G+C content of strain GG15(T) was 61.5 mol% based on its genomic sequence. Strain GG15(T) showed low digital DNA-DNA hybridization (<70 %) and average nucleotide identity values (<95 %) with other Microbulbifer species. As a result, a novel species within the genus Microbulbifer, named Microbulbifer magnicolonia sp. nov., is proposed. The type strain is GG15(T) (MCCC 1K08802(T)=KCTC 8210(T)).

A Gram-stain-negative bacterium with a rod-to-ovoid shape, named strain M216T, was isolated from sand sediment from the coastal intertidal zone of Huludao, Liaoning Province, China. Growth was observed at 8–40 °C (optimal, 30 °C), pH 5.5–9.5 (optimal, pH 6.5) and 0.5–14.0

Two Gram- stain- negative, rod- shaped, non- motile, aerobic and carotenoid- producing strains, belonging to the family Erythrobacteraceae, designated as H149T and Z2T, were isolated from tidal flat sediment samples collected in Hainan and Zhejiang, PR China, respectively. Growth of strain H149T occurred at 15-42 degrees C, 0-10.0 % (w/v) NaCl, and pH 6.0-8.5, with the optima at 35-37 degrees C, 3.0-3.5 % (w/v) NaCl and pH 7.0. Strain Z2T grew at 15-37 degrees C, 0-6.0 % (w/v) NaCl, and pH 6.0-9.5, with the optima at 25-30 degrees C, 0.5-1.0 % (w/v) NaCl and pH 6.0-6.5. Ubiquinone- 10 was the sole ubiquinone in two strains. The predominant cellular fatty acids of strain H149T were C16: 0, summed feature 3 and summed feature 8, while those of strain Z2T were C17: 1 omega 6c, summed feature 3 and summed feature 8. Strains H149T and Z2T shared diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and sphingoglycolipid as major polar lipids. The 16S rRNA gene sequence identity analysis indicated that strain H149T had the highest sequence identity of 98.4 % with Aurantiacibacter odishensis KCTC 23981T, and strain Z2T had that of 98.2 % with Qipengyuania pacifica NZ-96T. Phylogenetic trees based on 16S rRNA gene and core- genome sequences revealed that strains H149T and Z2T formed two independent clades in the genera Aurantiacibacter and Qipengyuania, respectively. Strain H149T had average nucleotide identity values of 74.0-81.3% and in silico DNA-DNA hybridization values of 18.5-23.1 % with Aurantiacibacter type strains, while strain Z2T had values of 73.3-78.7 % and 14.5-33.3 % with Qipengyuania type strains. The genomic DNA G+C contents of strains H149T and Z2T were 64.3 and 61.8 %, respectively. Based on the genetic, genomic, phylogenetic, physiological and chemotaxonomic results, strains H149T (=KCTC 8397T=MCCC 1K08920T) and Z2T (=KCTC 8396T=MCCC 1K08946T) are concluded to represent two novel Erythrobacteraceae species for which the names Aurantiacibacter hainanensis sp. nov. and Qipengyuania zhejiangensis sp. nov. are proposed, respectively.