Gramella antarctica sp. nov., isolated from marine surface sediment

Gramella oceanisediminis sp. nov., isolated from deep-sea sediment of the Indian Ocean

A taxonomic study was carried out on strain GC03-9^T, which was isolated from deep-sea sediment of the Indian Ocean. The bacterium was Gram-stain-negative, catalase-positive, oxidase-negative, rod-shaped and gliding motile. Growth was observed at salinities of 0-9 % and at temperatures of 10-42 °C. The isolate could degrade gelatin and aesculin. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain GC03-9^T belonged to the genus Gramella, with the highest sequence similarity to Gramella bathymodioli JCM 33424^T (97.9 %), followed by Gramella jeungdoensis KCTC 23123^T (97.2 %) and other species of the genus Gramella (93.4-96.3 %). The average nucleotide identity and the digital DNA-DNA hybridization estimate values between strain GC03-9^T and G. bathymodioli JCM 33424^T and G. jeungdoensis KCTC 23123^T were 25.1 and 18.7 % and 82.47 and 75.69 %, respectively. The principal fatty acids were iso-C_15 : 0 (28.0 %), iso-C_17 : 0 3OH (13.4 %), summed feature 9 (iso-C_17 : 1  ω9c and/or 10-methyl C_16 : 0; 13.3 %) and summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c; 11.0 %). The G+C content of the chromosomal DNA was 41.17 mol%. The respiratory quinone was determined to be menaquinone-6 (100 %). Phosphatidylethanolamine, one unknown phospholipid, three unknown aminolipids and two unknown polar lipids were present. The combined genotypic and phenotypic data showed that strain GC03-9^T represents a novel species within the genus Gramella, for which the name Gramella oceanisediminis sp. nov. is proposed, with the type strain GC03-9^T (=MCCC M25440^T=KCTC 92235^T).

Gramella sediminis sp. nov., isolated from a tidal flat of the Yellow Sea

A novel species of the genus Gramella , designated ASW11-100T, was isolated from a tidal flat sediment in the Yellow Sea, PR China. Phylogenetic analysis based on 16S rRNA gene sequences and single-copy orthologous clusters revealed that strain ASW11-100T belonged to the genus Gramella , and exhibited 16S rRNA gene sequence similarities of 98.9, 98.8 and 98.7 % to Gramella sabulilitoris HSMS-1T, Gramella sediminilitoris GHTF-27T and Gramella forsetii KT0803T, respectively. The genome of strain ASW11-100T harbours 2950 protein-coding genes and 105 carbohydrate-active enzymes including 38 glycoside hydrolases. Seventeen of the glycoside hydrolases are organized in five distinct polysaccharide utilization loci, which are predicted to involve in the degradation of starch, glucans, arabinoxylans, arabinomannan, arabinans and arabinogalactans. The genomic DNA G+C content was 37.3 mol%. The digital DNA–DNA hybridization and average nucleotide identity values between strain ASW11-100T and its closely related relatives were in ranges of 19.8–23.9% and 76.6–80.9 %, respectively. Cells of the isolate were Gram-negative, aerobic, non-flagellated and short rod-shaped. Carotenoid pigments were produced, but flexirubin-type pigments were absent. The major fatty acids (>10 %) were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1  ω6c and/or C16 : 1  ω7c). The sole respiratory quinone was menaquinone-6 and the major polar lipid was phosphatidylethanolamine. Based on the above polyphasic evidence, strain ASW11-100T should be considered to represent a novel Gramella species, for which the name Gramella sediminis sp. nov. is proposed. The type strain is ASW11-100T (=KCTC 82502T=MCCC 1K05580T).

Gramella crocea sp. nov., isolated from activated sludge of a seafood processing plant

A novel aerobic Gram-negative strain, designated as YB25^T, was isolated from an activated sludge sample collected from a seafood processing plant in Zhoushan, Zhejiang Province, China, and characterized by using a polyphasic taxonomic approach in this study. Strain YB25^T was motile by gliding, and short-rod-shaped. The isolate grew at 4-37 °C (optimum 28 °C), pH 6.0-9.0 (optimum pH 7.0) and 0.0-10.0% NaCl (optimum 2.0%, w/v). Phylogenetic analysis based on 16S rRNA gene indicated that strain YB25^T belonged to the genus Gramella, and showed the highest sequence similarity of 97.59% to Gramella lutea YJ019^T. The DNA G + C content was 39.5%. In silico DNA-DNA hybridization (DDH) and average nucleotide identity (ANI) values between strain YB25^T with most closely strains were below the threshold, which is considered to the phylogenetic definition of a novel species. Chemotaxonomic analysis indicated that the only respiratory quinone was menaquinone-6 and the major fatty acids were iso-C_15:0, anteiso-C_15:0, iso-C_17:0 3-OH, and summed feature 9 (iso-C_17:1ω9c and C_16:0 10 methyl). The polar lipid profile was composed of phosphatidylethanolamine, an unidentified phospholipid, two unidentified amino lipids, three unidentified glycolipids, and four unidentified lipids. Compared with the reference strains, strain YB25^T contained higher abundance of genes for carbohydrates metabolism,nitrogen metabolism, sulfur metabolism and respiration based on its genomic metabolic pathways and had been found a certain potential in the degradation of pectin. On the basis of the taxonomic evidence, strain YB25^T represents a novel species of the genus Gramella, for which the name Gramella crocea sp. nov. is proposed. The type strain is YB25^T (= KCTC 82680 ^T = MCCC 1K05761^T).

Salinity and nutrient modulate soil bacterial communities in the coastal wetland of the Yellow River Delta, China

The Yellow River Delta is the largest and youngest estuarine and coastal wetland in China and is experiencing the most active interactions of seawater and freshwater in the world. Bacteria played multifaceted influence on soil biogeochemical processes, and it was necessary to investigate the intermodulation between the soil factors and bacterial communities. Soil samples were collected at sites with different salinity degree, vegetations, and interference. The sequences of bacilli were tested using 16S rRNA sequencing method and operational taxonomic units were classified with 97% similarity. The soil was highly salinized and oligotrophic, and the wetland was nitrogen-restricted. Redundancy analysis suggested that factors related with seawater erosion were principal to drive the changes of soil bacterial communities and then the nutrient level and human disturbance. A broader implication was that, in the early succession stages of the coastal ecosystem, seawater erosion was the key driver of the variations of marine oligotrophic bacterial communities, while the increasing nutrient availability may enhance in the abundance of the riverine copiotrophs in the late stages. This study provided new insights on the characteristics of soil bacterial communities in estuarine and coastal wetlands.

Mesonia oceanica sp. nov., isolated from oceans during the Tara oceans expedition, with a preference for mesopelagic waters

Strain ISS653^T, isolated from Atlantic seawater, is a yellow pigmented, non-motile, Gram-reaction-negative rod-shaped bacterium, strictly aerobic and chemoorganotrophic, slightly halophilic (1-15 % NaCl) and mesophilic (4-37 °C), oxidase- and catalase-positive and proteolytic. Its major cellular fatty acids are iso-C_15 : 0, iso-C_15 : 0 2-OH, and iso-C_17 : 0 3-OH; the major identified phospholipid is phosphatidylethanolamine and the major respiratory quinone is MK6. Genome size is 4.28 Mbp and DNA G+C content is 34.9 mol%. 16S rRNA gene sequence similarity places the strain among members of the family Flavobacteriaceae, with the type strains of Mesonia phycicola (93.2 %), Salegentibacter mishustinae (93.1 %) and Mesonia mobilis (92.9 %) as closest relatives. Average amino acid identity (AAI) and average nucleotide identity (ANI) indices show highest values with M. mobilis (81 % AAI; 78.9 % ANI), M. phycicola (76 % AAI; 76.3 % ANI), Mesonia maritima (72 % AAI, 74.9 % ANI), Mesonia hippocampi (64 % AAI, 70.8 % ANI) and Mesonia algae (68 % AAI; 72.2 % ANI). Phylogenomic analysis using the Up-to-date-Bacterial Core Gene set (UBCG) merges strain ISS653^T in a clade with species of the genus Mesonia. We conclude that strain ISS653^T represents a novel species of the genus Mesonia for which we propose the name Mesonia oceanica sp. nov., and strain ISS653^T (=CECT 9532^T=LMG 31236^T) as the type strain. A second strain of the species, ISS1889 (=CECT 30008) was isolated from Pacific Ocean seawater. Data obtained throughout the Tara oceans expedition indicate that the species is more abundant in the mesopelagic dark ocean than in the photic layer and it is more frequent in the South Pacific, Indian and North Atlantic oceans.

Gramella sabulilitoris sp. nov., isolated from a marine sand

A Gram-stain-negative, aerobic, non-spore-forming, motile by gliding and rod-shaped bacterial strain, designated HSMS-1^T, was isolated from a marine sand collected from the Yellow Sea, Republic of Korea, and identified by a polyphasic taxonomic approach. The neighbour-joining phylogenetic tree of 16S rRNA gene sequences showed that HSMS-1^T fell within the clade comprising the type strains of species of the genus Gramella. HSMS-1^T exhibited 16S rRNA gene sequence similarity values of 99.0 and 98.7 % to the type strains of Gramella echinicola and Gramella sediminilitoris and of 93.3-98.5 % to the type strains of the other species of the genus Gramella. The ANI and dDDH values between HSMS-1^T and the type strains of G. echinicola, Gramella gaetbulicola, Gramella forsetii, Gramella salexigens, Gramella portivictoriae and Gramella flava were 72.6-79.3 % and 17.4-22.2 %, respectively. Mean DNA-DNA relatedness value between HSMS-1^T and the type strain of G. sediminilitoris was 18 %. HSMS-1^T contained MK-6 as the predominant menaquinone and iso-C_15 : 0, anteiso-C_15 : 0, iso-C_17 : 0 3-OH and iso-C_16 : 0 as the major fatty acids. The major polar lipid of HSMS-1^T was phosphatidylethanolamine. The DNA G+C content of HSMS-1^T from genomic sequence data was 39.2 %. Distinguishing phenotypic properties, along with the phylogenetic and genetic distinctiveness, revealed that HSMS-1^T is separated from recognized species of the genus Gramella. On the basis of the data presented, strain HSMS-1^T is considered to represent a novel species of the genus Gramella, for which the name Gramella sabulilitoris sp. nov. is proposed. The type strain is HSMS-1^T(=KACC 19899^T=NBRC 113648^T).

Culture-Dependent and -Independent Analyses Reveal the Diversity, Structure, and Assembly Mechanism of Benthic Bacterial Community in the Ross Sea, Antarctica

The benthic bacterial community in Antarctic continental shelf ecosystems are not well-documented. We collected 13 surface sediments from the Ross Sea, a biological hotspot in high-latitude maritime Antarctica undergoing rapid climate change and possible microflora shift, and aimed to study the diversity, structure and assembly mechanism of benthic bacterial community using both culture-dependent and -independent approaches. High-throughput sequencing of 16S rRNA gene amplicons revealed 370 OTUs distributed in 21 phyla and 284 genera. The bacterial community was dominated by Bacteroidetes, Gamma- and Alphaproteobacteria, and constituted by a compact, conserved and positively-correlated group of anaerobes and other competitive aerobic chemoheterotrophs. Null-model test based on βNTI and RCBray indicated that stochastic processes, including dispersal limitation and undominated fractions, were the main forces driving community assembly. On the other hand, environmental factors, mainly temperature, organic matter and chlorophyll, were significantly correlated with bacterial richness, diversity and community structure. Moreover, metabolic and physiological features of the prokaryotic taxa were mapped to evaluate the adaptive mechanisms and functional composition of the benthic bacterial community. Our study is helpful to understand the structural and functional aspects, as well as the ecological and biogeochemical role of the benthic bacterial community in the Ross Sea.