Roseobacter weihaiensis sp. nov., a cellulose-degrading bacterium isolated from intestinal content of Nipponacmea schrenckii collected from golden beach in Weihai, China

A Gram-staining-negative, dark pink, rod-shaped, amastigote and cellulose-degrading strain, designated H9T, was isolated from intestinal contents of Nipponacmea schrenckii. The isolate was able to grow at 4-42 °C (optimum, 25 °C), at pH 6.5-9.0 (optimum, pH 7.0), and with 0.0-11.0% (w/v) NaCl (optimum, 3.0-5.0%). Phylogenetic analysis of the 16S rRNA gene sequence suggested that isolate H9T belongs to the genus Roseobacter, neighboring Roseobacter insulae YSTF-M11T, Roseobacter cerasinus AI77T and Roseobacter ponti MM-7 T, and the pairwise sequence showed the highest similarity of 99.1% to Roseobacter insulae YSTF-M11T. The major fatty acid was summed feature 8 (C18:1ω7c and/or C18:1ω6c; 81.08%). The predominant respiratory quinone was Q-10. The polar lipids consisted of phosphatidylcholine, phosphatidylglycerol, an unknown lipid, and a small amount of an unknown phospholipid. The genome of strain H9T was 5,351,685 bp in length, and the DNA G + C content was 59.8%. The average amino acid identity (AAI), average nucleotide identity (ANI), and digital DNA hybridization (dDDH) values between strain H9T and closely related strains were 63.4-76.8%, 74.7-78.8%, and 13.4-19.7%, respectively. On the basis of the phenotypic, chemical taxonomic, and phylogenetic data, it is suggested that strain H9T should represent a novel species in the genus Roseobacter, for which the name Roseobacter weihaiensis sp. nov. is proposed. The type strain is H9T (= KCTC 82507 T = MCCC 1K04354T).

Preliminary identification and semi-quantitative characterization of a multi-faceted high-stability alginate lyase from marine microbe Seonamhaeicola algicola with anti-biofilm effect on Pseudomonas aeruginosa

Alginate lyases with unique characteristics for degrading alginate into size-defined oligosaccharide fractions, were considered as the potential agents for disrupting Pseudomonas aeruginosa biofilms. In our study, a novel endolytic PL-7 alginate lyase, named AlyG2, was cloned and expressed through Escherichia coli. This enzyme exhibited excellent properties: it maintained more than 85% activity at low temperatures of 4 °C and high temperatures of 70 °C. After 1 h of incubation at 4 °C, it still retained over 95% activity, demonstrating the ability to withstand low temperature. The acid-base and salt tolerance properties shown it preserves more than 50% activity in the pH range of 5.0 to 11.0 and in a high salt environment at 3000 mM NacCl, indicating its high stability in several aspects. More importantly, AlyG2 in our research was revealed to be effective at removing mature biofilms and inhibiting biofilm formation produced by Pseudomonas aeruginosa, and the inhibition and disruption rates were 47.25 ± 4.52% and 26.5 ± 6.72%, respectively. Additionally, the enzyme AlyG2 promoted biofilm disruption in combination with antibiotics, particularly manifesting the synergistic effect with erythromycin (FIC=0.5). In all, these results offered that AlyG2 with unique characteristics may be an effective technique for the clearance or disruption of biofilm produced by P. aeruginosa.

Phylogenetic diversity and functional potential of the microbial communities along the Bay of Bengal coast

The Bay of Bengal, the world's largest bay, is bordered by populous countries and rich in resources like fisheries, oil, gas, and minerals, while also hosting diverse marine ecosystems such as coral reefs, mangroves, and seagrass beds; regrettably, its microbial diversity and ecological significance have received limited research attention. Here, we present amplicon (16S and 18S) profiling and shotgun metagenomics data regarding microbial communities from BoB's eastern coast, viz., Saint Martin and Cox's Bazar, Bangladesh. From the 16S barcoding data, Proteobacteria appeared to be the dominant phylum in both locations, with Alteromonas, Methylophaga, Anaerospora, Marivita, and Vibrio dominating in Cox's Bazar and Pseudoalteromonas, Nautella, Marinomonas, Vibrio, and Alteromonas dominating the Saint Martin site. From the 18S barcoding data, Ochrophyta, Chlorophyta, and Protalveolata appeared among the most abundant eukaryotic divisions in both locations, with significantly higher abundance of Choanoflagellida, Florideophycidae, and Dinoflagellata in Cox's Bazar. The shotgun sequencing data reveals that in both locations, Alteromonas is the most prevalent bacterial genus, closely paralleling the dominance observed in the metabarcoding data, with Methylophaga in Cox's Bazar and Vibrio in Saint Martin. Functional annotations revealed that the microbial communities in these samples harbor genes for biofilm formation, quorum sensing, xenobiotics degradation, antimicrobial resistance, and a variety of other processes. Together, these results provide the first molecular insight into the functional and phylogenetic diversity of microbes along the BoB coast of Bangladesh. This baseline understanding of microbial community structure and functional potential will be critical for assessing impacts of climate change, pollution, and other anthropogenic disturbances on this ecologically and economically vital bay.

Red Sea Atlas of Coral-Associated Bacteria Highlights Common Microbiome Members and Their Distribution across Environmental Gradients-A Systematic Review

The Red Sea is a suitable model for studying coral reefs under climate change due to its strong environmental gradient that provides a window into future global warming scenarios. For instance, corals in the southern Red Sea thrive at temperatures predicted to occur at the end of the century in other biogeographic regions. Corals in the Red Sea thrive under contrasting thermal and environmental regimes along their latitudinal gradient. Because microbial communities associated with corals contribute to host physiology, we conducted a systematic review of the known diversity of Red Sea coral-associated bacteria, considering geographic location and host species. Our assessment comprises 54 studies of 67 coral host species employing cultivation-dependent and cultivation-independent techniques. Most studies have been conducted in the central and northern Red Sea, while the southern and western regions remain largely unexplored. Our data also show that, despite the high diversity of corals in the Red Sea, the most studied corals were Pocillopora verrucosa, Dipsastraea spp., Pleuractis granulosa, and Stylophora pistillata. Microbial diversity was dominated by bacteria from the class Gammaproteobacteria, while the most frequently occurring bacterial families included Rhodobacteraceae and Vibrionaceae. We also identified bacterial families exclusively associated with each of the studied coral orders: Scleractinia (n = 125), Alcyonacea (n = 7), and Capitata (n = 2). This review encompasses 20 years of research in the Red Sea, providing a baseline compendium for coral-associated bacterial diversity.

Jeotgalibacillus aurantiacus sp. nov., a novel orange-pigmented species with a carotenoid biosynthetic gene cluster, isolated from wetland soil

A Gram-stain-positive, orange-pigmented, rod-shaped and flagellated bacterial strain T12^T was isolated from wetland soil in Kunyu Mountain Wetland in Yantai, China. The strain was able to grow at 15-40 °C (optimum 37 °C), at 0.0-9.0% NaCl (optimum 2%, w/v) and at pH 5.5-9.0 (optimum 8.5). A phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain T12^T is a member of the family Planococcaceae, sharing 97.6% and 97.1% sequence similarity with the type strains of Jeotgalibacillus salarius and Jeotgalibacillus marinus, respectively. Genome-based analyses revealed a genome size of 3,506,682 bp and a DNA G + C content of 43.7%. Besides, the genome sequence led to 55.0-74.6% average amino acid identity values and 67.8-74.7% average nucleotide identity values between strain T12^T and the current closest relatives. Digital DNA-DNA hybridization of strain T12^T with the type strains of Jeotgalibacillus proteolyticus and J. marinus demonstrated 19.0% and 20.3% relatedness, respectively. The chemotaxonomic analysis showed that the sole quinone was MK-7. The predominant cellular fatty acids were iso-C_15:0, anteiso-C_15:0, C_16:1ω7c alcohol and iso-C_14:0. The polar lipids consisted of an unidentified aminolipid, phosphatidylglycerol, diphosphatidylglycerol and two unidentified phospholipids. Based on the polyphasic characterization, strain T12^T is considered to represent a novel species, for which the name Jeotgalibacillus aurantiacus sp. nov. is proposed. The type strain is T12^T (= KCTC 43296 ^T = MCCC 1K07171^T).

Flavihalobacter algicola gen. nov. sp. nov., a member of the family Flavobacteriaceae with alginate-degradation activity, isolated from marine alga Saccharina japonica

A Gram-stain-negative, aerobic, yellow, non-motile, rod-shaped and alginate-degrading bacterium, designated Dm15^T, was isolated from marine alga collected in Weihai, PR China. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain Dm15^T represents a distinct line of the family Flavobacteriaceae. Strain Dm15^T had the highest 16S rRNA gene sequence similarity to its closest phylogenetic neighbour Arcticiflavibacter luteus (96.7 %) and 93.7-96.4 % sequence similarity to other phylogenetic neighbours (Bizionia paragorgiae, Winogradskyella thalassocola, Ichthyenterobacterium magnum, Psychroserpens burtonensis and Arcticiflavibacter luteus) in the family Flavobacteriaceae. The novel isolate was able to grow at 10-40 °C (optimum, 30-33 °C), pH 7.0-9.0 (optimum, pH 7.0-7.5) and with 0.5-6.0 % NaCl (optimum 2.0-3.0 %, w/v). It could grow at 40 °C, and degrade alginate and cellulose, which were different from the neighbour genera. The draft genome consisted of 3395 genes with a total length of 3 798 431 bp and 34.1mol% G+C content. Especially, there were some specific genes coding for cellulase and alginate lyase, which provided a basis for the above phenotypic characteristics. The strain's genome sequence showed 71.1-80.2 % average amino acid identity values and 71.8-77.7 % average nucleotide identity values compared to the type strains of related genera within the family Flavobacteriaceae. It shared digital DNA-DNA hybridization identity of 19.8 and 20.9 % with I. magnum and A. luteus, respectively. The sole menaquinone was MK-6. The major fatty acids were iso-C_15 : 0 and iso-C_15 : 1 G. The polar lipids included six unidentified polar lipids, four unidentified aminolipids and phosphatidylethanolamine. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain Dm15^T represents a novel species of a new genus in the family Flavobacteriaceae, phylum Bacteroidetes, for which the name Flavihalobacter algicola gen. nov., sp. nov. is proposed. The type strain is Dm15^T (KCTC 42256^T=CICC 23815^T).

Seonamhaeicola maritimus sp. nov., isolated from coastal sediment

A Gram-stain-negative, facultatively anaerobic, non-motile, rod-shaped and orange-pigmented bacterium, designated 1505^T, was isolated from marine sediment that was obtained off the coast of Weihai, PR China. Strain 1505^T was found to grow at 10-35 °C (optimum, 28 °C), at pH 6.0-9.0 (optimum, 7.5) and in the presence of 1-4 % (w/v) NaCl (optimum, 2 %). Cells were positive for oxidase and catalase activity. The 16S rRNA gene based phylogenetic analysis revealed that the nearest phylogenetic neighbours of strain 1505^T were Seonamhaeicola algicola Gy8^T (97.1 %), Seonamhaeicola marinus B011^T (96.3 %) and Seonamhaeicola aphaedonensis KCTC 32578^T (95.6 %). Based on phylogenomic analysis, the average nucleotide identity values between strain 1505^T and S. algicola Gy8^T, S. marinus B011^T and S. aphaedonensis KCTC 32578^T were 75.9, 76.0 and 77.7 %, respectively; the digital DNA-DNA hybridization values based on the draft genomes between strain 1505^T and S. algicola Gy8^T, S. marinus B011^T and S. aphaedonensis KCTC 32578^T were 20.0, 20.7 and 21.4 %, respectively. Menaquinone-6 (MK-6) was detected as the major respiratory quinone. The dominant cellular fatty acids were iso-C_15 : 1 G and C_18 : 1ω9c. The DNA G+C content of strain 1505^T was 33.3 mol%. The polar lipids included phosphatidylethanolamine, six aminolipids and four unidentified lipids. Based on its phylogenetic and phenotypic characteristics, strain 1505^T is considered to represent a novel species of the genus Seonamhaeicola, for which the name Seonamhaeicola maritimus sp. nov. is proposed. The type strain is 1505^T (=KCTC 72528^T=MCCC 1H00389^T).

Seonamhaeicola sediminis sp. nov., isolated from marine sediment

A novel Gram-stain-negative, orange, rod or curved rod, facultatively anaerobic, gliding bacterial strain, designated strain W255^T, was isolated from Xiaoshi Island, Weihai, China. The strain W255^T grows optimally at a 28 °C, pH 7.5, and 3.0% (w/v) NaCl environment. Its colonies are circular, orange, non-transparent, smooth, and approximately 0.2-0.8 mm in diameter, after being cultured for 72 h on marine agar 2216. Cells of the strain W255^T are 0.3-0.8 µm wide and 1.0-4.0 µm long, catalase-positive and oxidase-positive. The major cellular fatty acids are iso-C_15:0, iso-C_15:1 G, and iso-C_15:0 3-OH. The sole respiratory quinone is MK-6. The major polar lipids include phosphatidylethanolamine, one unidentified amino lipid, one amino glycolipid, and two unidentified lipids (L1 and L2). The phylogenetic analysis based on 16S rRNA gene sequences indicated that strain W255^T has the highest similarities with the type strain of the type species of the genus Seonamhaeicola, S. aphaedonensis KCTC 32578^T (97.2%), and moderate with 'S. acroporae' KCTC 62713^T (96.5%), S. algicola Gy8^T (95.4%) and S. marinus B011^T (94.5%). The ANI and dDDH values between strain W255^T and S. aphaedonensis KCTC 32578^T are 86.6% and 31.3%, respectively. The genomic DNA G + C content is 33.5 mol%. On the basis of gene annotation, it was observed that strain W255^T have the abilities of nitrate reduction and utilizing various carbon sources, suggesting that this strain might be an important participant in the nitrogen cycle and carbon cycle in the marine environment. Based on the phenotypic, chemotaxonomic and phylogenetic analysis, strain W255^T has been considered as a novel species of the genus Seonamhaeicola, for which the name Seonamhaeicola sediminis sp. nov. is proposed. The type strain is W255^T (= MCCC 1H00377^T = KCTC 72085^T).

Marinospirillum perlucidum sp. nov., a novel helical bacterium isolated from a sea cucumber culture pond

Strain F3212^T, Gram-stain-negative, aerobic, helical and motile bacterium, was isolated from the marine sediment collected in a sea cucumber culture pond located in Rongcheng, China. Strain F3212^T grew optimally at pH 8.5, at 30 °C and in the presence of 3.0 % (w/v) NaCl. Phylogenetic analysis, based on 16S rRNA gene sequences, indicated that strain F3212^T belongs to the genus Marinospirillum, clustering with M. celere, M. alkaliphilum, M. minutulum, M. megaterium and M. insulare (with 96.4, 94.6, 93.1, 92.4 and 92.1 % 16S rRNA gene sequence similarities, respectively). The chemotaxonomic properties of strain F3212^T were similar to those of members of the genus Marinospirillum. Q-8 was the sole respiratory ubiquinone and the genomic DNA G+C content was 53.3 mol%. The major fatty acids were C_18 : 1 ω9c, C_16 : 0 and C_18 : 0. The polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentifed lipid and an unidentified aminophospholipid. The average nucleotide identity scores for strains M. celere DSM 18438^T and M. minutulum DSM 6287^T were 74.5 and 69.4 %, respectively. The DNA-DNA homologies with M. celere DSM 18438^T and M. minutulum DSM 6287^T were less than 20 %. It's concluded that strain F3212^T represents a new species of the genus Marinospirillum, for which the name Marinospirillum perlucidum sp. nov. is proposed. The type strain is F3212^T (=KCTC 52892^T=MCCC 1H00198^T).

Seonamhaeicola acroporae sp. nov., a marine species of the family Flavobacteriaceae isolated from the hard coral Acropora formosa

A novel marine flavobacterial species, designated 3KA7-17^T, was isolated from the hard coral Acropora formosa D. collected in Japan. The strain was pale-orange pigmented, Gram-stain negative, strictly aerobic, coccus shaped, and non-motile. Preliminary analysis based on the 16S rRNA gene sequence revealed an affiliation with the family Flavobacteriaceae of the phylum Bacteroidetes, and it had the greatest sequence similarity (96.0%) to Seonamhaeicola algicola Gy8^T. The DNA G + C content was 34.3 mol%. MK-6 was the major menaquinone, with iso-C15:1 H and/or C13:0 3-OH (24.3%), iso-C15:0 (19.5%), iso-C15:0 3-OH (14.2%), and iso-C17:0 3-OH (15.9%) as the main (> 10%) cellular fatty acids. The major polar lipid profile consisted of phosphatidylethanolamine, two unidentified aminolipids, and two unidentified lipids. Based on distinct phylogenetic and phenotypic evidence, the strain represents a novel species of the genus Seonamhaeicola, for which the name Seonamhaeicola acroporae sp. nov. is proposed and the type strain is 3KA7-17^T (= KCTC 62713^T = NBRC 113410^T).