Sulfitobacter pacificus sp. nov., isolated from the red alga Pyropia yezoensis

Effects of Hyphomonas Strains on the Growth of Red Algae Pyropia Species by Attaching Specifically to Their Rhizoids

Bacteria and marine macroalgae form close associations, while various bacteria affect the morphogenesis and growth of macroalgae. Hyphomonas strains exhibit normal morphogenetic activity in protoplasts of the red alga Pyropia yezoensis (nori). However, the effects of the bacteria on the growth of Pyropia from protoplast cells to regenerated thalli remain unknown. Here, we assessed the growth of P. yezoensis and Pyropia tenera using combined cultures of three Hyphomonas strains (LNM10-16, SCM-2, and LNM-9) and three algal media (artificial seawater with vitamins, artificial seawater, and natural seawater) over 7 weeks. Third week after culture, the three Hyphomonas strains showed almost similar levels of normal growth activity for both Pyropia species. However, at 7 weeks, significant differences were observed among the three Hyphomonas strains in terms of length, length-to-width ratio, and normal morphology of Pyropia thalli. LNM10-16 significantly promoted the thalli length and length-to-width ratios of both Pyropia species in artificial seawater without vitamins and natural seawater, compared with the other two Hyphomonas strains. P. yezoensis cultured in artificial seawater with vitamins showed a much higher demand for LNM10-16 in development of the thalli length than P. tenera. These results may be explained by differences in the growth activities of Hyphomonas strains and the nutrient requirements of Pyropia species. Furthermore, the bacteria were more specifically attached to the rhizoid surfaces of both species. This study is the first to reveal that Hyphomonas strains affect the growth of Pyropia species by attaching to their rhizoids.

Sulfitobacter alexandrii sp. nov., a new microalgae growth-promoting bacterium with exopolysaccharides bioflocculanting potential isolated from marine phycosphere

Marine phycosphere harbors unique cross-kingdom associations with enormous ecological significance in aquatic ecosystems as well as relevance for algal biotechnology industry. During our investigating the microbial composition and bioactivity of marine phycosphere microbiota (PM), a novel lightly yellowish and versatile bacterium designated strain AM1-D1^T was isolated from cultivable PM of marine dinoflagellate Alexandrium minutum amtk4 that produces high levels of paralytic shellfish poisoning toxins (PSTs). Strain AM1-D1^T demonstrates notable bioflocculanting bioactivity with bacterial exopolysaccharides (EPS), and microalgae growth-promoting (MGP) potential toward its algal host. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain AM1-D1^T was affiliated to the members of genus Sulfitobacter within the family Rhodobacteraceae, showing the highest sequence similarity of 97.9% with Sulfitobacter noctilucae NB-68^T, and below 97.8% with other type strains. The complete genome of strain AM1-D1^T consisted of a circular 3.84-Mb chromosome and five circular plasmids (185, 95, 15, 205 and 348 Kb, respectively) with the G+C content of 64.6%. Low values obtained by phylogenomic calculations on the average nucleotide identity (ANI, 77.2%), average amino acid identity (AAI, 74.7%) and digital DNA-DNA hybridization (dDDH, 18.6%) unequivocally separated strain AM1-D1^T from its closest relative. The main polar lipids were identified as phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, diphosphatidylglycerol, one unidentified phospholipid and one unidentified lipid. The predominant fatty acids (> 10%) were C_18:1 ω7c, C_19:0 cyclo ω8c and C_16:0. The respiratory quinone was Q-10. The genome of strain AM1-D1^T was predicted to encode series of gene clusters responsible for sulfur oxidation (sox) and utilization of dissolved organic sulfur exometabolites from marine dinoflagellates, taurine (tau) and dimethylsulfoniopropionate (DMSP) (dmd), as well as supplementary vitamin B₁₂ (cob), photosynthesis carotenoids (crt) which are pivotal components during algae-bacteria interactions. Based on the evidences by the polyphasic characterizations, strain AM1-D1^T represents a novel species of the genus Sulfitobacter, for which the name Sulfitobacter alexandrii sp. nov. is proposed. The type strain is AM1-D1^T (= CCTCC 2017277T = KCTC 62491^T).

Sulfitobacter algicola sp. nov., isolated from green algae

A novel Gram-stain-negative, aerobic, non-flagellated, non-motile, oval-rod-shaped and light pink to light tawny-pigmented bacterial strain (designated 1151^T) were isolated from marine green algae obtained from the coastal seawater of Weihai, China. Strain 1151^T was found to grow at 15-37 °C (optimum, 33 °C), pH 7.0-9.5 (optimum, 7.5-8.5) and in the presence of 1-6% (w/v) NaCl (optimum, 3%). Cells were oxidase-positive and catalase-positive. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 1151^T was a member of the genus Sulfitobacter and exhibited the hightest sequence similarity to Sulfitobacter indolifex DSM 14862^T (96.6%), followed by the sequence similarity to Sulfitobacter aestuarii hydD52^T (96.5%) and Sulfitobacter profundi SAORIC-263^T (96.5%). The average nucleotide identity and digital DDH values between strain 1151^T and Sulfitobacter indolifex DSM 14862^T were 69.9% and 20.9%, respectively. The average amino acid identity between strain 1151^T and Sulfitobacter pontiacus DSM 10014^T (type strain of the type species) was 62.3%. Q-10 was detected as the sole respiratory quinone. The dominant cellular fatty acids were sum feature 8 (C_{18: 1}ω7c; 44.1%), C_{20: 1}ω7c (29.7%) and C_{18: 0} (11.7%). The DNA G + C content of strain 1151^T was 51.8 mol%. The polar lipids included phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), and three unidentified lipids (L1, L2 and L3). Based on the phylogenetic and phenotypic characteristics, strain 1151^T is considered to represent a novel species of the genus Sulfitobacter, for which the name Sulfitobacter algicola sp. nov. is proposed. The type strain is 1151^T (= KCTC 72513^T = MCCC 1H00384^T).

Antarcticimicrobium sediminis gen. nov., sp. nov., isolated from Antarctic intertidal sediment, transfer of Ruegeria lutea to Antarcticimicrobium gen. nov. as Antarcticimicrobium luteum comb. nov

A Gram-stain-negative, aerobic, non-flagellated and rod- or ovoid-shaped bacterium, designated as strain S4J41^T, was isolated from Antarctic intertidal sediment. The isolate grew at 0-37 °C and with 0.5-10 % (w/v) NaCl. It reduced nitrate to nitrite and hydrolysed Tween 80 and gelatin. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain S4J41^T constituted a distinct phylogenetic line within the family Rhodobacteraceae and was closely related with some species in the genera Ruegeria, Phaeobacter, Pseudopuniceibacterium, Sulfitobacter, Puniceibacterium and Poseidonocella with 98.6-95.7 % 16S rRNA gene sequence similarities. The major cellular fatty acids were C_16 : 0, summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c) and C_18 : 0 and the major polar lipids were phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, phosphatidylethanolamine and one unidentified aminolipid. The sole respiratory quinone was Q-10. The genomic DNA G+C content of strain S4J41^T was 60.3 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic data obtained in this study, strain S4J41^T is considered to represent a novel species in a new genus within the family Rhodobacteraceae, for which the name Antarcticimicrobium sediminis gen. nov., sp. nov. is proposed. The type strain is S4J41^T (=MCCC 1K03508^T=KCTC 62793^T). Moreover, the transfer of Ruegeria lutea Kim et al. 2019 to Antarcticimicrobium gen. nov. as Antarcticimicrobium luteum comb. nov. (type strain 318-1^T=JCM 30927^T=KCTC 72105^T) is also proposed.

Exposure to TiO2 nanoparticles induces shifts in the microbiota composition of Mytilus galloprovincialis hemolymph

It is now recognized that host microbiome, the community of microorganisms that colonize the animal body (e.g. microbiota) and their genomes, play an important role in the health status of all organisms, from nutrient processing to protection from disease. In particular, the complex, bilateral interactions between the host innate immune system and the microbiota are crucial in maintaining whole body homeostasis. The development of nanotechnology is raising concern on the potential impact of nanoparticles-NPs on human and environmental health. Titanium dioxide-nTiO₂, one of the most widely NP in use, has been shown to affect the gut microbiota of mammals and fish, as well as to potentially alter microbial communities. In the marine bivalve Mytilus galloprovincialis, nTiO₂ has been previously shown to interact with hemolymph components, thus resulting in immunomodulation. However, no information is available on the possible impact of NPs on the microbiome of marine organisms. Bivalves host high microbial abundance and diversity, and alteration of their microbiota, in both tissues and hemolymph, in response to stressful conditions has been linked to a compromised health status and susceptibility to diseases. In this work, the effects of nTiO₂ exposure (100 μg/L, 4 days) on Mytilus hemolymph microbiota were investigated by 16S rRNA gene-based profiling. Immune parameters were also evaluated. Although hemolymph microbiota of control and nTiO₂-treated mussels revealed a similar core composition, nTiO₂ exposure affected the abundance of different genera, with decreases in some (e.g. Shewanella, Kistimonas, Vibrio) and increases in others (e.g. Stenotrophomonas). The immunomodulatory effects of nTiO₂ were confirmed by the increase in the bactericidal activity of whole hemolymph. These represent the first data on the effects of NPs on the microbiome of marine invertebrates, and suggest that the shift in hemolymph microbiome composition induced by nTiO₂ may result from the interplay between the microbiota and the immune system.

Sulfitobacter profundi sp. nov., isolated from deep seawater

A Gram-stain-negative, rod-shaped, obligately aerobic, chemoheterotrophic bacterium which is motile by means of a single polar flagellum, designated SAORIC-263^T, was isolated from deep seawater of the Pacific Ocean. Phylogenetic analyses based on 16S rRNA gene sequences and genomebased phylogeny revealed that strain SAORIC-263^T belonged to the genus Sulfitobacter and shared 96.1-99.9% 16S rRNA gene sequence similarities with Sulfitobacter species. Wholegenome sequencing of strain SAORIC-263^T revealed a genome size of 3.9Mbp and DNA G+C content of 61.3 mol%. The SAORIC-263^T genome shared an average nucleotide identity and digital DNA-DNA hybridization of 79.1-88.5% and 18.9-35.0%, respectively, with other Sulfitobacter genomes. The SAORIC-263^T genome contained the genes related to benzoate degradation, which are frequently found in deep-sea metagenome. The strain contained summed feature 8 (C_18:1ω7c), C_18:1ω7c 11-methyl, and C_16:0 as the predominant cellular fatty acids as well as ubiquinone-10 (Q-10) as the major respiratory quinone. The major polar lipids of the strain were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, and aminolipid. On the basis of taxonomic data obtained in this study, it is suggested that strain SAORIC-263^T represents a novel species of the genus Sulfitobacter, for which the name Sulfitobacter profundi sp. nov. is proposed. The type strain is SAORIC-263^T (= KACC 21183^T = NBRC 113428^T).

List of new names and new combinations previously effectively, but not validly, published

The purpose of this announcement is to effect the valid publication of the following effectively published new names and new combinations under the procedure described in the Bacteriological Code (1990 Revision). Authors and other individuals wishing to have new names and/or combinations included in future lists should send three copies of the pertinent reprint or photocopies thereof, or an electronic copy of the published paper to the IJSEM Editorial Office for confirmation that all of the other requirements for valid publication have been met. It is also a requirement of IJSEM and the ICSP that authors of new species, new subspecies and new combinations provide evidence that types are deposited in two recognized culture collections in two different countries. Note that the date of valid publication of these new names and combinations is the date of publication of this list, not the date of the original publication of the names and combinations. The authors of the new names and combinations are as given below. Inclusion of a name on these lists validates the publication of the name and thereby makes it available in the nomenclature of prokaryotes. The inclusion of a name on this list is not to be construed as taxonomic acceptance of the taxon to which the name is applied. Indeed, some of these names may, in time, be shown to be synonyms, or the organisms may be transferred to another genus, thus necessitating the creation of a new combination.