Hyphobacterium marinum sp. nov. and Hyphobacterium lacteum sp. nov., isolated from marine sediment.

Two bacterial strains, Y60-23T and HN-65T, were isolated from marine sediment samples collected from Xiaoshi Island, Weihai, and Dongzhai Harbour, Haikou, PR China, respectively. Based on the 16S rRNA gene sequences, strain Y60-23T exhibited 96.0% similarity to its most related type strain Hyphobacterium vulgare KCTC 52487T, while strain HN-65T exhibited 97.3% similarity to its most related type strain Hyphobacterium indicum 2ED5T. The 16S rRNA gene sequence similarity between the two strains was 95.8%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains Y60-23T and HN-65T belonged to the genus Hyphobacterium. Cells of strains Y60-23T and HN-65T were rod-shaped, Gram-stain-negative, aerobic, non-motile, prosthecate and multiplied by binary fission. The major cellular fatty acids (>10.0%) of strain Y60-23T were C18 : 1 ω7c and C17 : 0, while those of strain HN-65T were iso-C17 : 1 ω9c, iso-C17 : 0 and C18 : 1 ω7c. The major respiratory quinone in both strains was ubiquinone-10 (Q-10) and the major polar lipids were monoglycosyl diglyceride, sulfoquinovosyl diacylglycerol and glucuronopyranosyl diglyceride. The genomic DNA G+C contents of strains Y60-23T and HN-65T were 63.9 and 60.7 mol%, respectively. The average nucleotide identity value between the two strains was 72.1% and the DNA-DNA hybridization value was 18.4%, clearly distinguishing them from each other. According to the results of the phenotypic, chemotaxonomic, phylogenetic and genomic analyses, the two strains represented two novel species within the genus Hyphobacterium, for which the names Hyphobacterium marinum sp. nov. and Hyphobacterium lacteum sp. nov. were proposed with the type strains Y60-23T (=MCCC 1H01433T=KCTC 8172T) and HN-65T (=MCCC 1H01434T=KCTC 8169T), respectively.

Gilvimarinus gilvus sp. nov. and Gilvimarinus algae sp. nov., isolated from kelp seedlings.

Two novel rod-shaped, strictly aerobic, non-motile and Gram-stain-negative bacterial strains, designated SDUM040013T and SDUM040014T, were isolated from kelp seedlings in Weihai, PR China. Cells of strain SDUM040013T were 0.3-0.4 µm wide and 0.8-1.8 µm long, catalase-positive and oxidase-positive. Growth of SDUM040013T was observed at 0-37 °C (optimum, 28-30 °C) and pH 5.5-9 (optimum, pH 8.0) and in the presence of 1-8 % (w/v) NaCl (optimum, 2 %). The DNA G+C content of strain SDUM040013T was 50.5 %. Strain SDUM040013T showed the highest 16S rRNA gene sequence similarity (97.1 %) to Gilvimarinus chinensis. Cells of strain SDUM040014T were 0.4-0.5 µm wide and 1.0-1.4 µm long, catalase-positive and oxidase-positive. Growth of SDUM040014T was observed at 4-40 °C (optimum, 28-30 °C) and pH 5.5-9 (optimum, pH 8.5) and in the presence of 0-8 % (w/v) NaCl (optimum, 2 %). The DNA G+C content of strain SDUM040014T was 56.5 %. Strain SDUM040014T showed the highest 16S rRNA gene sequence similarity (96.2%) to Gilvimarinus polysaccharolyticus. The isoprenoid quinone of both strains was Q-8 and the predominant fatty acids were summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), summed feature 8 (C18 : 1 ω7c) and C16 : 0. Diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine were the major polar lipids. Given these phenotypic and chemotaxonomic properties, as well as phylogenetic data, strains SDUM040013T and SDUM040014T were considered to represent two novel species of the genus Gilvimarinus, for which the names Gilvimarinus gilvus sp. nov. and Gilvimarinus algae sp. nov. are proposed. The type strains are SDUM040013T (=KCTC 8123T=MCCC 1H01413T) and SDUM040014T (=KCTC 8124T=MCCC 1H01414T), respectively.

Maribellus mangrovi sp. nov., an iron-reducing bacterium isolated from mangrove sediment.

A novel facultatively anaerobic and Gram-stain-negative bacterium, designated FJH33T, was isolated from mangrove sediment sampled in Zhangzhou, PR China. Cells of strain FJH33T were rod-shaped or slightly curved-shaped, with widths of 0.3-0.5 µm and lengths of 1.0-3.0 µm. Optimum growth of strain FJH33T occurred in the presence of 3 % NaCl (w/v), at 33 °C and at pH 7.0. Oxidase activity was negative, while catalase activity was positive. Its iron-reducing ability was determined. Based on 16S rRNA gene sequence similarity, strain FJH33T was most closely related to Maribellus luteus XSD2T (95.1 %), followed by Maribellus sediminis Y2-1-60T (95.0 %) and Maribellus maritimus 5E3T (94.9 %). Genome analysis of strains FJH33T and M. luteus XSD2T revealed low genome relatedness, with an average nucleotide identity value of 73.8% and a digital DNA-DNA hybridization value of 19.0%. Phylogenetic trees built from 16S rRNA genes and genome sequences showed that strain FJH33T represents a relatively independent phylogenetic lineage within the genus Maribellus. The major cellular fatty acids (≥10 %) were iso-C15 : 0 and C18 : 1 ω9c. The sole respiratory quinone was MK-7. The polar lipids consisted of phosphatidylethanolamine, diphosphatidylcholine, diphosphatidyglycerol and one unidentified lipid. The DNA G+C content was 41.4 mol%. Based on the integrated results of phylogenetic, physiological, biochemical and chemotaxonomic characterizations, we propose that strain FJH33T represents a novel species of the genus Maribellus, for which the name Maribellus mangrovi sp. nov. is proposed. The type strain is FJH33T (=KCTC 102210T=MCCC 1H01459T).

Marinobacter sediminicola sp. nov. and Marinobacter xiaoshiensis sp. nov., Isolated from Coastal Sediment.

Two Gram-stain-negative, facultative anaerobic, rod-shaped, motile bacterial strains, designated F26243T and F60267T were isolated from coastal sediment in Weihai, China. Strains F26243T and F60267T were grown at 4-40 °C (optimum 33 °C), pH 7.0-9.5 and pH 6.5-9.5 (optimum at pH 7.0), in the presence of 1.0-7.0% (w/v) NaCl (optimum 2.5%) and 1.0-12.0% (w/v) NaCl (optimum 2.0%), respectively. The 16S rRNA gene sequences phylogenetic analysis showed that strains F26243T and F60267T are closely related to the genus Marinobacter and exhibited the highest sequence similarities to Marinobacter salexigens HJR7T (97.7% and 98.0%, respectively), the similarity between two isolates was 96.7%. Strains F26243T and F60267T displayed genomic DNA G + C content of 53.6% and 53.8%, respectively. When compared to the M. salexigens HJR7T, the average nucleotide identity (ANI) values were 83.7% and 84.1%, and the percentage of conserved proteins (POCP) values were 79.9% and 84.6%, respectively. Ubiquinone 9 (Q-9) was the only respiratory quinone detected in both isolates. The major cellular fatty acids (> 10.0%) were summed feature 3 (comprising C16:1ω7c and/or C16:1ω6c), C16:0 and C18:1ω9c. The polar lipid profiles of strains F26243T and F60267T contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidyldimethylethanolamine, phosphatidylglycerol, aminophospholipid and one unidentified phospholipid. Based on genomic characteristics, phenotypic and chemotaxonomic, strains F26243T and F60267T represent two novel species of the genus Marinobacter, for which the names Marinobacter sediminicola sp. nov. and Marinobacter xiaoshiensis sp. nov. are proposed, the type strains are F26243T (= KCTC 92640T = MCCC 1H01345T) and F60267T (= KCTC 92638T = MCCC 1H01346T).

Winogradskyella pelagia sp. nov., isolated from coastal sediment.

An orange-pigmented, Gram-stain-negative, strictly aerobic, non-flagellated and rod-shaped bacterium, designated strain DF17T, was isolated from coastal sediment collected from Jingzi Wharf, Weihai, PR China. The optimal growth conditions were determined to be at 30 °C, pH 7.5, and in 3 % (w/v) NaCl. According to phylogenetic analysis of the 16S rRNA gene sequence, strain DF17T showed the highest sequence similarity of 96.9 % to Winogradskyella aquimaris KCTC 23502T. The DNA G+C content was 35.8 mol%, and the major fatty acids were iso-C15 : 1 G, iso-C15 : 0, and iso-C17 : 0 3-OH. The major polar lipids were two aminoglycolipids, one phosphatidylethanolamine and four unidentified lipids. The predominant respiratory quinone was menaquinone-6 (MK-6). The average nucleotide identity, digital DNA-DNA hybridization, and amino acid identity values between strain DF17T and other Winogradskyella species were below the species delineation thresholds of 69.35-72.95 %, 16.9-19.6 % and 71.25-78.93 %, respectively. On the basis of its phenotypic, genetic and physiological characteristics, strain DF17T is suggested to represent a novel species of the genus Winogradskyella, for which the name Winogradskyella pelagia sp. nov. is proposed. The type strain is DF17T (MCCC 1H00456T=KCTC 82421T).

Elongatibacter sediminis gen. nov., sp. nov., isolated from intertidal sediment, and genomic comparison with all genera in the family Wenzhouxiangellaceae.

A novel slightly halophilic, aerobic, and Gram-stain-negative strain, designated as CH-27T, was isolated during a bacterial resource investigation of intertidal sediment collected from Xiaoshi Island in Weihai, PR China. Cells of strain CH-27T were rod-shaped with widths of 0.3-0.6 µm and lengths of 2.0-11.0 µm. Strain CH-27T grew optimally at 37 °C, pH 7.0 and with 2.0 % (w/v) NaCl. Catalase activity was weakly positive and oxidase activity was positive. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CH-27T was most related to Marinihelvus fidelis KCTC 92639T (93.6 %), followed by Wenzhouxiangella marina MCCC 1K00261T (92.0 %). Based on genome comparisons between strain CH-27T and M. fidelis KCTC 92639T, the average amino acid identity was 63.6 % and the percentage of conserved proteins was 48.3 %. The major cellular fatty acid of strain CH-27T (≥10 %) was iso-C15 : 0 and the sole respiratory quinone was quinone-8. The polar lipids were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, and aminophospholipid. The DNA G+C content was 62.7 mol%. Based on comprehensive analysis of its phylogenetic, physiological, biochemical, and chemotaxonomic characteristics, strain CH-27T represents a novel species in a novel genus, for which the name Elongatibacter sediminis gen. nov., sp.nov. is proposed. The type strain is CH-27T (=MCCC 1H00480T=KCTC 8011T).

Preliminary study of BF/C2 on immune mechanism of grass carp against GCRV infection.

BF/C2 is a crucial molecule in the coagulation complement cascade pathway and plays a significant role in the immune response of grass carp through the classical, alternative, and lectin pathways during GCRV infection. In vivo experiments demonstrated that the mRNA expression levels of BF/C2 (A, B) in grass carp positively correlated with GCRV viral replication at various stages of infection. Excessive inflammation leading to death coincided with peak levels of BF/C2 (A, B) mRNA expression and GCRV viral replication. Correspondingly, BF/C2 (A, B) recombinant protein, CIK cells and GCRV co-incubation experiments yielded similar findings. Therefore, 3 h (incubation period) and 9 h (death period) were selected as critical points for this study. Transcriptome sequencing analysis revealed significant differences in the expression of BF/C2A and BF/C2B during different stages of CIK infection with GCRV and compared to the blank control group (PBS). Specifically, the BF/C2A_3 and BF/C2A_9 groups exhibited 2729 and 2228 differentially expressed genes (DEGs), respectively, with 1436 upregulated and 1293 downregulated in the former, and 1324 upregulated and 904 downregulated in the latter. The BF/C2B_3 and BF/C2B_9 groups showed 2303 and 1547 DEGs, respectively, with 1368 upregulated and 935 downregulated in the former, and 818 upregulated and 729 downregulated in the latter. KEGG functional enrichment analysis of these DEGs identified shared pathways between BF/C2A and PBS groups at 3 and 9 h, including the C-type lectin receptor signaling pathway, protein processing in the endoplasmic reticulum, Toll-like receptor signaling pathway, Salmonella infection, apoptosis, tight junction, and adipocytokine signaling pathway. Additionally, the BF/C2B groups at 3 and 9 h shared pathways related to protein processing in the endoplasmic reticulum, glycolysis/gluconeogenesis, and biosynthesis of amino acids. The mRNA levels of these DEGs were validated in cellular models, confirming consistency with the sequencing results. In addition, the mRNA expression levels of these candidate genes (mapk1, il1b, rela, nfkbiab, akt3a, hyou1, hsp90b1, dnajc3a et al.) in the head kidney, kidney, liver and spleen of grass carp immune tissue were significantly different from those of the control group by BF/C2 (A, B) protein injection in vivo. These candidate genes play an important role in the response of BF/C2 (A, B) to GCRV infection and it also further confirmed that BF/C2 (A, B) of grass carp plays an important role in coping with GCRV infection.

Helicobacter pylori infection delays neutrophil apoptosis and exacerbates inflammatory response.

Aim: Understanding molecular mechanisms of Helicobacter pylori (H. pylori)-induced inflammation is important for developing new therapeutic strategies for gastrointestinal diseases.Materials & methods: We designed an H. pylori-neutrophil infection model and explored the effects of H. pylori infection on neutrophils.Results: H. pylori infected neutrophils showed a low level of apoptosis. H. pylori stimulation activated the NACHT/LRR/PYD domain-containing protein 3 (NLRP3)-gasdermin-D (GSDMD) pathway for interleukin (IL)-1ß secretion. However, IL-1ß secretion was not completely dependent on GSDMD, as inhibition of autophagy significantly reduced IL-1ß release, and autophagy-related molecules were significantly upregulated in H. pylori-infected neutrophils.Conclusion: Therefore, H. pylori infection inhibits neutrophils apoptosis and induces IL-1ß secretion through autophagy. These findings may be utilized to formulate therapeutic strategies against H. pylori mediated chronic gastritis.

[Box: see text].

Cultivating the uncultured: Harnessing the "sandwich agar plate" approach to isolate heme-dependent bacteria from marine sediment.

In the classical microbial isolation technique, the isolation process inevitably destroys all microbial interactions and thus makes it difficult to culture the many microorganisms that rely on these interactions for survival. In this study, we designed a simple coculture technique named the "sandwich agar plate method," which maintains microbial interactions throughout the isolation and pure culture processes. The total yield of uncultured species in sandwich agar plates based on eight helper strains was almost 10-fold that of the control group. Many uncultured species displayed commensal lifestyles. Further study found that heme was the growth-promoting factor of some marine commensal bacteria. Subsequent genomic analysis revealed that heme auxotrophies were common in various biotopes and prevalent in many uncultured microbial taxa. Moreover, our study supported that the survival strategies of heme auxotrophy in different habitats varied considerably. These findings highlight that cocultivation based on the "sandwich agar plate method" could be developed and used to isolate more uncultured bacteria.

Aequorivita sediminis sp. nov. and Aequorivita marina sp. nov., isolated from marine sediment.

Two Gram-stain-negative, rod-shaped, non-motile, strictly aerobic strains, forming yellow colonies and designated F6058T and S2608T, were isolated from marine sediment collected in Weihai, PR China. Both strains grow at 4-40 °C (optimum, 30-33 °C), pH 6.0-7.5 (optimum, pH 6.5) and in the presence of 0-7.0 % (w/v) NaCl. The optimum NaCl concentrations for strains F6058T and S2608T were 2.0 % and 2.5 %, respectively. Phylogenetic analysis of the 16S rRNA gene sequences indicated that strains F6058T and S2608T share an evolutionary lineage with members of the genus Aequorivita. The isolates exhibited a 16S rRNA gene sequence similarity of 96.7 % to each other. Strains F6058T exhibited the highest 16S rRNA gene sequence similarity to Aequorivita xiaoshiensis F64183T (98.8 %), and S2608T was most similar to Aequorivita capsosiphonis A71T (96.9 %). Iso-C15:0, anteiso-C15:0 and iso-C17:0 3-OH were the major fatty acids of strains F6058T and S2608T. The sole respiratory quinone of both isolates was menaquinone 6 (MK-6). The polar lipid profiles of the isolates both consisted of phosphatidylethanolamine and phosphoglycolipids; however, strain F6058T exhibited one glycolipid, one aminolipid and two unidentified polar lipids, and strain S2608T also had two glycolipids and one unidentified polar lipid. The DNA G+C contents of strains F6058T and S2608T were 34.6 % and 37.7 mol%, respectively. Based on their phenotypic, chemotaxonomic and genomic characteristics, strains F6058T and S2608T were considered to represent novel species of the genus Aequorivita, for which the names Aequorivita sediminis sp. nov. and Aequorivita marina sp. nov. were proposed. The type strains are F6058T (=KCTC 92653T=MCCC 1H01358T) and S2608T (KCTC 92652T=MCCC 1H01361T).

The role of MASP1 in the complement system and expression characteristics in response to GCRV infection in grass carp.

The grass carp (Ctenopharyngodon idella) constitutes a significant economic resource within the aquaculture sector of our nation, yet it has been chronically afflicted by the Grass Carp Reovirus (GCRV) disease. The complement system, a vital component of fish's innate immunity, plays a crucial role in combating viral infections. This research investigates the potential role of MASP1, a key molecule in the lectin pathway of the complement system, in the GCRV infection in grass carp. An analysis of the molecular characteristics of MASP1 in grass carp revealed that its identity and similarity percentages range from 35.10 to 91.00 % and 35.30-91.00 %, respectively, in comparison to other species. Phylogenetically, MASP1 in C. idella aligns closely with species such as Danio rerio, Cyprinus carpio, and Carassius carassius, exhibiting chromosomal collinearity with the zebrafish. Subsequent tissue analysis in both healthy and GCRV-infected grass carp indicated that MASP1's basal expression was predominantly in the liver. Post-GCRV infection, MASP1 expression in various tissues exhibited temporal variations: peaking in the liver on day 5, spleen on day 7, and kidney on day 14. Furthermore, employing Complement Component 3 (C3) as a benchmark for complement system activation, it was observed that MASP1 could activate and cleave C3 to C3b. MASP1 also demonstrated an inhibitory effect on GCRV replication (compared with the control group, VP2 and VP7 decreased by 6.82-fold and 4.37-fold) and enhanced the expression of antiviral genes, namely IRF3, IRF7 and IFN1 (compared with the control group, increased 2.25-fold, 45.38-fold and 22.37-fold, respectively). In vivo protein injection experiments substantiated MASP1's influence on the relative mRNA expression levels of C3 in various tissues and its protein expression in serum. This study also verified that C3 could modulate the expression of antiviral genes such as IFN1 and IRF3.

Direct Degradation of Fresh and Dried Macroalgae by Agarivorans albus B2Z047.

Marine macroalgae are increasingly recognized for their significant biological and economic potential. The key to unlocking this potential lies in the efficient degradation of all carbohydrates from the macroalgae biomass. However, a variety of polysaccharides (alginate, cellulose, fucoidan, and laminarin), are difficult to degrade simultaneously in a short time. In this study, the brown alga Saccharina japonica was found to be rapidly and thoroughly degraded by the marine bacterium Agarivorans albus B2Z047. This strain harbors a broad spectrum of carbohydrate-active enzymes capable of degrading various polysaccharides, making it uniquely equipped to efficiently break down both fresh and dried kelp, achieving a hydrolysis rate of up to 52%. A transcriptomic analysis elucidated the presence of pivotal enzyme genes implicated in the degradation pathways of alginate, cellulose, fucoidan, and laminarin. This discovery highlights the bacterium's capability for the efficient and comprehensive conversion of kelp biomass, indicating its significant potential in biotechnological applications for macroalgae resource utilization.

Dietary resveratrol improves the flesh quality of Siberian sturgeon (Acipenser baerii) by enhancing myofiber growth, nutrient accumulation and antioxidant capacity.

BACKGROUND: In aquaculture, sturgeons are generally maintained in the confined spaces, which not only hinders sturgeon movement, but also threatens their flesh quality that seriously concerned by aquaculture industry. As a typical antioxidant, resveratrol can improve the flesh quality of livestock and poultry. However, the mechanism of resveratrol's effect on the muscle of Siberian sturgeon is still unclear. RESULTS: In this study, the dietary resveratrol increased the myofiber diameter, the content of the amino acids, antioxidant capacity markers (CAT, LDH and SOD) levels and the expression levels of mTORC1 and MYH9 in muscle of Siberian sturgeon. Further transcriptome analysis displayed that ROS production-related pathways ("Oxidative phosphorylation" and "Chemical carcinogenes-reactive oxygen species") were enriched in KEGG analysis, and the expression levels of genes related to the production of ROS (COX4, COX6A, ATPeF1A, etc.) in mitochondria were significantly down-regulated, while the expression levels of genes related to scavenging ROS (SOD1) were up-regulated. CONCLUSIONS: In summary, this study reveals that resveratrol may promote the flesh quality of Siberian sturgeon probably by enhancing myofiber growth, nutritional value and the antioxidant capacity of muscle, which has certain reference significance for the development of a new type of feed for Siberian sturgeon.

Ottowia cancrivicina sp. nov., isolated from human stomach.

A Gram-negative, facultative anaerobic, non-motile and rod-shaped bacterium, designated 10c7w1T, was isolated from a human gastrointestinal tract. Colonies on agar plates were small, circular, smooth and beige. The optimal growth conditions were determined to be 37 °C, pH 7.0-7.5 and 0 % (w/v) NaCl. Comparative analysis of complete 16S rRNA gene sequences revealed that strain 10c7w1T showed the highest sequence similarity of 95.8 % to Ottowia beijingensis MCCC 1A01410T, followed by Ottowia thiooxydans (95.2 %) JCM 11629T. The average amino acid identity values between 10c7w1T and O. beijingensis MCCC 1A01410T and O. thiooxydans JCM 11629T were above 60 % (71.4 and 69.5 %). The average nucleotide identity values between strain 10c7w1T and O. beijingensis MCCC 1A01410T and O. thiooxydans JCM 11629T were 76.9 and 72.5 %, respectively. The dominant fatty acids (≥10 %) were straight chain ones, with summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c), summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c) and C16 : 00 being the most abundant. Q-8 was the only respiratory quinone. The major polar lipids of strain 10c7w1T were phosphatidylethanolamine, diphosphatidylglycerol and unknown lipids. The DNA G+C content of strain 10c7w1T was 63.6 mol%. On the basis of phylogenetic, phenotypic and chemotaxonomic data, strain 10c7w1T is considered to represent a novel species within the genus Ottowia, for which the name Ottowia cancrivicina sp. nov. is proposed. The type strain is 10c7w1T (=MCCC 1H01399T=KCTC 92200T).

Microbaculum marinisediminis sp. nov., isolated from marine sediment.

A novel Gram-stain-negative and facultatively anaerobic bacterium, designated A6E488T, was isolated from intertidal sediment collected from Xiaoshi Island, Weihai, PR China (122° 1' E 37° 31' N). Cells of strain A6E488T were rod-shaped with widths of 0.3-0.4 µm and lengths of 1.1-1.8 µm. The optimal growth conditions were determined to be in 1 % (w/v) NaCl, at 37 °C, and at pH 7.0. The predominant fatty acids (≥10 %) were C19 : 0 cyclo ω8c (59.7 %) and summed feature 8 (13.8 %, C18 : 1 ω7c and/or C18 : 1 ω6c). The sole isoprenoid quinone was Q-10. Oxidase activity was negative but catalase activity was positive. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminolipid, one unidentified glycolipid, and one unidentified lipid. Based on phylogenetic analysis of 16S rRNA gene sequences, strain A6E488T showed the highest sequence similarity to Microbaculum marinum MCCC 1K03192T (97.6 %). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain A6E488T and M. marinum MCCC 1K03192T did not exceed 78 and 22 %, respectively. These values are below the recommended thresholds of 95 % (ANI) and 70 % (dDDH) for prokaryotic species delineation. On the basis of gene annotation, it was observed that strain A6E488T possesses the capability for thiosulphate oxidation, suggesting that this strain might be important in the sulphur cycle. Based on the results of phenotypic, genotypic, and chemical characterization, strain A6E488T is considered to represent a novel species of the genus Microbaculum, for which the name Microbaculum marinisediminis sp. nov. is proposed. The type strain is A6E488T (=KCTC 92197T=MCCC 1H00516T).

Phenotypic and genotypic characterization of Marinobacterium weihaiense sp. nov. and Marinobacterium marinum sp. nov., isolated from marine sediment, and genomic properties of the genus Marinobacterium.

In this study, two novel bacterial strains were isolated from coastal sediment of Weihai, China. The two strains were Gram-stain-negative and facultatively aerobic, designated 3-1745T and A346T. Based on phenotypic, genetic and phylogenetic properties, strains 3-1745T and A346T represent two novel species of the genus Marinobacterium. The results of genome analysis revealed many central carbohydrate metabolism pathways such as gluconeogenesis, pyruvate oxidation, tricyclic acid cycle, pentose phosphate pathway and PRPP biosynthesis in the genus Marinobacterium. The ability of strains 3-1745T and A346T to utilize volatile fatty acids was experimentally confirmed. Polyhydroxyalkanoate synthases (PhaA, PhaB and PhaC) for the synthesis of polyhydroxyalkanoates were prevalent in the genus Marinobacterium. Multiple BGCs (biosynthetic gene clusters) including betalactone, ectoine, ranthipeptide, redox-cofactor, RiPPs (ribosomally synthesized post-translationally modified peptides) and T3PKS (polyketide synthases) in the genome of the genus Marinobacterium were found. Additional genome analyses suggested that the genus Marinobacterium contained diverse potential mechanisms of salt tolerance and mainly utilized oligosaccharides. This is the first report on broad genomic analyses of the genus Marinobacterium with the description of two novel species and potential ecological and biotechnological implications.

Marinicella marina sp. nov. and Marinicella gelatinilytica sp. nov., isolated from coastal sediment, and genome analysis and habitat distribution of the genus Marinicella.

Three Marinicella strains, X102, S1101T and S6413T, were isolated from sediment samples from different coasts of Weihai, PR China. All strains were Gram-stain-negative, rod-shaped and non-motile. The predominant fatty acids of all strains were iso-C15 : 0 and summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c) and the major polar lipids comprised phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. Strains X102 and S1101T shared 100 % 16S rRNA gene sequence similarity, and strains S1101T/X102 and S6413T had 95.4 % similarity. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strains S1101T and X102 were 99.9 and 99.2 %, respectively. Strain S1101T had ANI values of 69.1-72.9% and dDDH values of 17.9-20.5 % to members of the genus Marinicella. Strain S6413T had ANI values of 69.1-77.5% and dDDH values of 17.6-21.5 % to members of the genus Marinicella. The results of phylogenetic and comparative genomic analysis showed that the three strains belong to two novel species in the genus Marinicella, and strains X102 and S1101T represented one novel species, and strain S6413T represented another novel species. The result of BOX-PCR and genomic analysis showed that X102 and S1101T were not the same strain. The phylogenetic analyses and genomic comparisons, combined with phylogenetic, phenotypic and chemotaxonomic features, strongly supported that the three strains should be classified as representing two novel species of the genus Marinicella, for which the names Marinicella marina sp. nov. and Marinicella gelatinilytica sp. nov. are proposed, respectively. The type strains of the two novel species are S1101T (=KCTC 92642T=MCCC 1H01359T) and S6413T (=KCTC 92641T=MCCC 1H01362T), respectively. In addition, all previously described isolates of Marinicella were isolated from marine environments, but our study showed that Marinicella is also distributed in non-/low-saline habitats (e.g. animal gut, soil and indoor surface), which broadened our perception of the environmental distribution of Marinicella.

Robiginitalea aurantiaca sp. nov. and Algoriphagus sediminis sp. nov., isolated from coastal sediment.

Two novel rod-shaped, Gram-stain-negative, aerobic and non-motile bacterial strains, designated M39T and C2-7T, were isolated from the coastal sediment of Xiaoshi Island, Weihai, PR China. Growth of strain M39T occurred at 15-37 °C, at pH 6.0-9.0 and in the presence of 1.0-9.0 % (w/v) NaCl. Strain C2-7T grew at 15-40 °C, at pH 6.0-8.0 and in the presence of 0.5-8.0 % (w/v) NaCl. Phylogenetic analysis based 16S rRNA gene sequences revealed that strains M39T and C2-7T belong to the phylum Bacteroidota. Based on the results of 16S rRNA gene sequence analysis, the closest relative of strain M39T was Robiginitalea marina KCTC 92035T (95.4 %), and the closest relative of strain C2-7T was Algoriphagus namhaensis DPG-3T (97.0 %). The percentage of conserved protein and average nucleotide identity values between strain M39T and some species of the genus Robiginitalea were 66.9-77.6% and 69.3-71.0 %, respectively, while those between strain C2-7T and some species of the genus Algoriphagus were 68.0-70.1% and 56.1-72.6 %, respectively. The major cellular fatty acids (>10 %) of strain M39T consisted of iso-C15 : 1 F, iso-C15 : 0 and iso-C17 : 0 3-OH, while those of strain C2-7T were iso-C15 : 0 and C16 : 1 ω7c/C16 : 1 ω6c. MK-6 was the only respiratory quinone that was compatible with the genus of strain M39T. The predominant menaquinone of strain C2-7T was MK-7. The major polar lipids of strain M39T were phosphatidylethanolamine and glycolipids, and those of strain C2-7T were phosphatidylethanolamine, one unidentified aminolipid and four unidentified lipids. The DNA G+C contents of strains M39T and C2-7T were 46.9 and 40.8 mol%, respectively. Based upon the results presented in this study, strains M39T and C2-7T represent novel species of the genera Robiginitalea and Algoriphagus, respectively, for which the names Robiginitalea aurantiaca sp. nov. and Algoriphagus sediminis sp. nov. are proposed with the type strains M39T (=MCCC 1H00498T=KCTC 92014T) and C2-7T (=MCCC 1H00414T=KCTC 92027T).

Phylogenetics and biomineralization of a novel magnetotactic Gammaproteobacterium from a freshwater lake in Beijing, China.

Magnetotactic bacteria (MTB) have the remarkable capability of producing intracellularly membrane-enveloped magnetic nanocrystals (i.e. magnetosomes) and swimming along geomagnetic field lines. Despite more than 50 years of research, bacterial diversity and magnetosome biomineralization within MTB are relatively less known in the Gammaproteobacteria class than other groups. This is incompatible with the status of Gammaproteobacteria as the most diverse class of gram-negative bacteria with a number of ecologically important bacteria. Here, we identify a novel MTB strain YYHR-1 affiliated with the Gammaproteobacteria class of the Pseudomonadota phylum from a freshwater lake. In YYHR-1, most magnetosome crystals are organized into a long chain aligned along the cell long axis; unusually, a few small superparamagnetic crystals are located at the side of the chain, off the main chain axis. Micromagnetic simulations indicate that magnetostatic interactions among adjacent crystals within a chain reduce the Gibbs energy to enhance chain stability. Genomic analysis suggests that duplication of magnetosome gene clusters may result in off-chain magnetosomes formation. By integrating available genomic data from Gammaproteobacteria, the phylogenetic position of MTB in this class is reassigned here. Our new findings expand knowledge about MTB diversity and magnetosome biomineralization, and deepen understanding of the phylogenetics of the Gammaproteobacteria.

Tumebacillus lacus sp. nov., isolated from lake water.

A Gram-stain-positive, aerobic, rod-shaped, endospore-forming and motile, by means of peritrichous flagella, bacterium, designated DT12T, was isolated from a lake water sample from Datun Lake of Yunnan Province, PR China. The results of phylogenetic analysis based on 16S rRNA gene sequence and the concatenated alignment of 120 ubiquitous single-copy proteins indicated that the novel strain represented a member of the genus Tumebacillus. The sole quinone was menaquinone-7 and the cell-wall peptidoglycan was type-A1γ. The major fatty acids (>10 %) of the novel strain were iso-C15 : 0 and anteiso-C15 : 0, while the major polar lipids were phosphatidylmonomethylethanolamine, phosphatidylethanolamine and phosphatidylglycerol. The results of phylogenetic analyses combined with phylogenetic, phenotypic and chemotaxonomic features, strongly supported the hypothesis that the strain should be classified as representing a novel species of the genus Tumebacillus, for which the name Tumebacillus lacus sp. nov. is proposed. The type strain is DT12T (=KCTC 33958T= MCCC 1H00320T). The genomic analysis revealed that DT12T has various biosynthetic gene clusters for secondary metabolites, and members of the genus Tumebacillus may represent a promising source of new natural products. Our study also showed that members of the genus Tumebacillus are widely distributed in a variety of habitats throughout the globe, particularly in soils, human-, animal- and plant-associated environments. Members of the genus Tumebacillus may have an important role in the growth and health of humans, plants and animals.