Pelagibacterium nitratireducens sp.nov., A Marine Alphaproteobacterium Isolated from the East China Sea

Pelagibacterium flavum sp. nov., Isolated from Soil Sample

A Gram-stain-negative, yellow, moist and circular, aerobic, motile, and rod-shaped bacterium, designated YIM 151497T, was isolated from soil sample collected from Blue-Bridge, Weizhou Island, Guangxi province, China. Classification using a polyphasic approach suggested that strain YIM 151497T belonged to the genus Pelagibacterium, and was closely relevant to Pelagibacterium nitratireducens JLT2005T (98.8%), Pelagibacterium halotolerans CGMCC 1.7692T (98.7%), Pelagibacterium lixinzhangensis H64T (98.1%), and Pelagibacterium luteolum CGMCC 1.10267T (97.1%). The growth ranges of temperature, pH, and NaCl were 4-40 ℃, pH 4.0-10.0, and 0-7% NaCl, respectively. It was positive for catalase and oxidase. The primary respiratory quinone was Q-10. The elemental fatty acids were Summed Feature 8 (constituting C18:1ω7c and/or C18:1ω6c), C19:0 cyclo ω8c, C16:0, and C18:1ω7c 11-methyl. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, and three unidentified glycolipids. The DNA G+C content based on the complete genome sequence was 60.7 mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) between strain YIM 151497T and species of Pelagibacterium were in the ranges of 73.9-86.3% and 19.7-31.3%, respectively. The Average Amino Acid Identity (AAI) between strain YIM 151497T and species of Pelagibacterium were in the ranges of 68.8-88.8%. On the basis of these data, strain YIM 151497T is considered to represent a novel species of the genus Pelagibacterium with the name of Pelagibacterium flavum sp. nov. Type strain is strain YIM 151497T (= KCTC 49826T = CGMCC 1.61521T = MCCC 1K08053T).

Mariluticola halotolerans gen. nov., sp. nov., a novel member of the family Devosiaceae isolated from South China Sea sediment

A novel member of class Alphaproteobacteria was isolated from marine sediment of the South China Sea. Cells of strain LMO-2^T were Gram-stain negative, greyish in colour, motile, with a single lateral flagellum and short rod in shape with a slight curve. Strain LMO-2^T was positive for oxidase and negative for catalase. The bacterium grew aerobically at 10-40 °C (optimum, 25-30 °C), pH 5.5-10.0 (optimum, pH 7.0) and 0-9 % NaCl (w/v; optimum, 2-3 %). Phylogenetic analysis of the 16S rRNA gene sequence and phylogenomic analysis of the whole genome sequence indicated that strain LMO-2^T represents a new genus and a new species within the family Devosiaceae, class Alphaproteobacteria, phylum Pseudomonadota. Comparisons of the 16S rRNA gene sequences of strain LMO-2^T showed 94.8 % similarity to its closest relative. The genome size is ~3.45 Mbp with a DNA G+C content of 58.17 mol%. The strain possesses potential capability for the degradation of complex organic matter, i.e. fatty acid and benzoate. The predominant cellular fatty acids (>10 %) were C_16 : 0 and C_18 : 1 ω7c 11-methyl. The sole respiratory quinone was ubiquinone-10. The major identified polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phospholipid. Based on the polyphasic taxonomic data, strain LMO-2^T represents a novel genus and a novel species for which the name Mariluticola halotolerans gen. nov., sp. nov., was proposed in the family Devosiaceae. The type strain is LMO-2^T (=CGMCC 1.19273^T=JCM 34934^T).

Pelagibacterium xiamenense sp. nov., isolated from intertidal sediment

A Gram-stain-negative, obligately aerobic bacterium, designated as HS1C4-1T, was isolated from a sediment sample from the tidal zone of the Haicang Coast, Xiamen, Fujian Province, PR China. The strain was yellowish-coloured, non-gliding, rod-shaped and motile, with a single polar flagellum. Cells of HS1C4-1T were oxidase- and catalase-positive. The strain could grow at 15–55 °C (optimum 37 °C), pH 6.0–10.0 (optimum, pH 7.0–9.0), in the presence of 0–12 % (optimum, 1 %) NaCl (w/v). Phylogenetic analysis based on the 16S rRNA gene sequences indicated that HS1C4-1T represented a member of the genus Pelagibacterium , and shared the highest similarity to Pelagibacterium luteolum CGMCC 1.10267T (97.6 %). Digital DNA–DNA hybridization values and average nucleotide identity between HS1C4-1T and all the species of genus Pelagibacterium were 18.7–20.2 % and 77.3–78.4 %, respectively. The principal fatty acids (>10 %) were C19 : 0 cyclo ω8c (50.5 %) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 29.1%). Q-10 was the sole respiratory quinone. The polar lipids included diphosphatidylglycerol, phosphatidylglycerol, two unidentified glycolipids and six unidentified lipids. The G+C content of the chromosomal DNA was 62.9 %. On the basis of phylogenetic, phenotypic, chemotaxonomic and genomic characteristics, HS1C4-1T represents a novel species within the genus Pelagibacterium , for which the name Pelagibacterium xiamenense sp. nov. is proposed. The type strain is HS1C4-1T (=MCCC 1A18759T=KCTC 92097T).

Structure and variation of root-associated bacterial communities of Cyperus rotundus L. in the contaminated soils around Pb/Zn mine sites

Soil contamination due to mining activities is a great concern in China. Although the effects of mining pollution resulting in changes of soil characteristics and the microbiome have been documented, studies on the responses of plant root-associated microbial assemblages remain scarce. In this work, we collected bulk soil, rhizosphere soil, and root endosphere samples of Cyperus rotundus L (Cyp) plants from two Pb/Zn mines, of which, one was abandoned (SL) and the other was active (GD), to investigate the bacterial community responses across different site contamination levels and Cyp plant compartments. For comparison, one unpolluted site (SD) was included. Results revealed that soils from the SL and GD sites were seriously contaminated by metal(loid)s, including Pb, Zn, As, and Sb. Bacterial richness and diversity depended on the sampling site and plant compartment. All sample types from the SL site had the lowest bacterial diversities and their bacterial communities also exhibited distinct patterns compared to GD and SD samples. As for the specific sampling site, bacterial communities from the root endosphere exhibited different patterns from those in bulk and rhizosphere soil. Compared to the GD and SD sites, the root endosphere and the rhizosphere soil from the SL site shared core microbes, including Halomonas, Pelagibacterium, and Chelativorans, suggesting that they play key roles in Cyp plant survival in such harsh environments.

Pelagibacterium limicola sp. nov., isolated from a soda alkali-saline soil

A Gram-staining negative, motile, non-spore-forming, rod-shaped bacterium, designated NAJP-14^T, was isolated from the alkali-saline soil in Heilongjiang, Northeast China. Phylogenetic analysis based on 16S rRNA gene sequencing illustrated that strain NAJP-14^T was a member of the genus Pelagibacterium, and shared 94.6-96.6% sequence identities to species from the genus Pelagibacterium. Strain NAJP-14^T grew at 20-45 °C (optimum, 30 °C), pH 7.0-10.0 (optimum, pH 8.0) and in the presence of up to 5% w/v NaCl. The menaquinone was determined to be Q (10). The major fatty acids were identified as C_18:1w6c (38.7%), C_16:0 (16.2%) and C_19:0 cyclo w8c (13.9%). The G + C content of the genomic DNA was 61.2%. Out of the 3442 predicted genes, 3391 were protein-coding genes and 51 were ncRNA. Digital DNA-DNA hybridization (dDDH) estimation and average nucleotide identity (ANI) of the strain NAJP-14^T and the type strains of related species in the same family ranged between 17.9 and 21.8% and between 61.4 and 78.7%, respectively. Based on these data, it is concluded that strain NAJP-14^T possesses sufficient characteristics to differentiate it from all recognized Pelagibacterium species, and should be considered as a novel species for which the name Pelagibacterium limicola sp. nov. is proposed. The type strain is NAJP-14^T (= CGMCC 1.16631^T, = JCM 33746^T).

Bacterial-derived nutrient and carbon source-sink behaviors in a sandy beach subterranean estuary

Microbial communities in subterranean estuaries play important roles in the biogeochemical cycle. However, the microorganisms associated with biogeochemical behaviors in subterranean estuaries have received little attention. Here, the bacterial communities were compared between the fresh and saline groundwater in a subterranean estuary. Correlation analysis between bacterial groups and salinity indicated that different species represented different groundwater types. The key bacterial groups found along the subterranean estuaries have been shown to influence organic pollutant degradation and nitrate utilization. These species may be potential candidates for the in situ bioremediation of subterranean estuaries that are contaminated with pollutants. The utilization of nitrate and organic pollutants by bacteria in subterranean estuaries serves as a nitrate sink and inorganic carbon source. Our results show the role of bacteria in remediating pollutants through submarine groundwater discharge (SGD) to the coastal ocean, and specific species may be helpful in selecting reasonable groundwater end-members and reducing SGD uncertainties.

Pelagibacterium sediminicola sp. nov., isolated from tidal flat sediment

A Gram-stain-negative, obligately aerobic, cream-coloured, non-gliding, motile with a single polar flagellum and rod-shaped bacterium, designated IMCC34151^T, was isolated from tidal flat sediment of the Yellow Sea, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain IMCC34151^T belonged to the genus Pelagibacterium of the family Hyphomicrobiaceae and shared 94.7-96.8 % sequence similarities to Pelagibacterium species. Whole-genome sequencing of strain IMCC34151^T revealed a genome size of 3.2 Mbp and a DNA G+C content of 62.6 mol%. The strain contained summed feature 8 (C_18 : 1 ω7c and/or C_18 : 1 ω6c), C_19 : 0cyclo ω8c and C_16 : 0 as the major fatty acids and ubiquinone-10 (Q-10) as the major respiratory quinone. The polar lipids detected in the strain were phosphatidylglycerol, diphosphatidylglycerol, two unidentified glycolipids and 12 unidentified lipids. On the basis of its phylogenetic and phenotypic characteristics, strain IMCC34151^T is considered to represent a novel species of the genus Pelagibacterium, for which the name Pelagibacteriumsediminicola sp. nov. (type strain IMCC34151^T =KACC 19595^T=NBRC 113420^T) is proposed.

Pelagibacterium lacus sp. nov., isolated from lake water

A Gram-stain-negative, strictly aerobic, oxidase- and catalase-positive, non-gliding, motile with a single polar flagellum, and short rod-shaped bacterial strain, designated XYN52^T, was isolated from a freshwater lake in the west of China. Phylogenetic analysis of the 16S rRNA gene determined that strain XYN52^T was a member of the genus Pelagibacterium within the family Hyphomicrobiaceae. Strain XYN52^T was able to grow at 4-37 °C (optimum, 30 °C), pH 6.0-9.0 (pH 7.5) and in the presence of up to 7.0 % w/v NaCl (0.5 %).The major quinone was ubiquinone 10. The major cellular fatty acids were C18 : 1ω6c/C18 : 1ω7c, C19 : 0ω8c cyclo and 11-methyl C18 : 1ω7c. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and three kinds of glycolipids. The genomic DNA G+C content was 64.5 mol%. On the basis of these data, strain XYN52^T represents a novel species in the genus Pelagibacterium, for which the name Pelagibacterium lacus sp. nov. is proposed. The type strain is XYN52^T (=KCTC 62845^T=MCCC 1H00348^T).