Arenibacter antarcticus sp. nov., isolated from marine sediment

Pseudidiomarina fusca sp. nov., Isolated from the Surface Seawater of the Western Pacific Ocean

The Gram-negative marine bacterium GXY010T, which has been isolated from the surface seawater of the western Pacific Ocean, is aerobic, non-motile and non-flagellated. Strain GXY010T exhibits growth across a temperature range of 10-42 °C (optimal at 37 °C), pH tolerance from 7.0 to 11.0 (optimal at 7.5) and a NaCl concentration ranging from 1.0 to 15.0% (w/v, optimal at 5.0%). Ubiquinone-8 (Q-8) was the predominant isoprenoid quinone in strain GXY010T. The dominant fatty acids (>10%) of strain GXY010T were iso-C15:0 (14.65%), summed feature 9 (iso-C17:1ω9c and/or 10-methyl C16:0) (12.41%), iso-C17:0 (10.85%) and summed feature 3 (C16:1ω7c and/or C16:1ω6c) (10.41%). Phosphatidylethanolamine (PE), phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), unidentifiable glycolipid (GL) and four non-identifiable aminolipids (AL1-AL4) were the predominant polar lipids of strain GXY010T. The genomic DNA G+C content was identified as a result of 48.0% for strain GXY010T. The strain GXY010T genome consisted of 2,766,857 bp, with 2664 Open Reading Frames (ORFs), including 2586 Coding sequences (CDSs) and 78 RNAs. Strain GXY010T showed Average Nucleotide Identity (ANI) values of 73.4% and 70.6% and DNA-DNA hybridization (DDH) values of 19.2% and 14.5% with reference species Pseudidiomarina tainanensis MCCC 1A02633T (=PIN1T) and Pseudidiomarina taiwanensis MCCC 1A00163T (=PIT1T). From the results of the polyphasic analysis, a newly named species, Pseudidiomarina fusca sp. nov. within the genus Pseudidiomarina, was proposed. The type strain of Pseudidiomarina fusca is GXY010T (=JCM 35760T = MCCC M28199T = KCTC 92693T).

Shewanella jiangmenensis sp. nov., isolated from aquaculture water

A Gram-stain-negative and facultatively anaerobic bacterial strain designated as JM162201^T was isolated from aquaculture water for farming Pacific white shrimp (Litopenaeus vannamei). The genome size of strain JM162201^T was 4,436,316 bp, and the genomic DNA G + C content was 55.0%. Phylogenetic analysis based on 16S rRNA gene sequences and genomes showed that strain JM162201^T belonged to the genus Shewanella and was closely related to Shewanella litorisediminis SMK1-12^T (97.1%), Shewanella khirikhana TH2012^T (97.0%), and Shewanella amazonensis SB2B^T (96.0%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain JM162201^T and three reference type strains were below the recognized thresholds of 95.0-96.0% (for ANI) and 70.0% (for dDDH) for species delineation. Growth occurred at 10-40 °C (optimum, 30 °C), at pH 4.0-10.0 (optimum, 7.0-8.0), and in 0-6.0% NaCl (w/v, optimum, 0-0.1%). The major cellular fatty acids of strain JM162201^T were summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), C_17:1 ω8c, iso-C_15:0, C_16:0, and C_15:0. The predominant quinones were MK7, Q-7, and Q-8. The major polar lipids were phosphatidylethanolamine (PE) and phosphatidylglycerol (PG). Based on the polyphasic taxonomical analyses, strain JM162201^T represents a novel species of the genus Shewanella, for which the name Shewanella jiangmenensis sp. nov. is proposed, with the type strain JM162201^T (= GDMCC 1.2006^T = KCTC 82340^T).

Microbial Succession under Freeze-Thaw Events and Its Potential for Hydrocarbon Degradation in Nutrient-Amended Antarctic Soil

The polar regions have relatively low richness and diversity of plants and animals, and the basis of the entire ecological chain is supported by microbial diversity. In these regions, understanding the microbial response against environmental factors and anthropogenic disturbances is essential to understand patterns better, prevent isolated events, and apply biotechnology strategies. The Antarctic continent has been increasingly affected by anthropogenic contamination, and its constant temperature fluctuations limit the application of clean recovery strategies, such as bioremediation. We evaluated the bacterial response in oil-contaminated soil through a nutrient-amended microcosm experiment using two temperature regimes: (i) 4 °C and (ii) a freeze–thaw cycle (FTC) alternating between −20 and 4 °C. Bacterial taxa, such as Myxococcales, Chitinophagaceae, and Acidimicrobiales, were strongly related to the FTC. Rhodococcus was positively related to contaminated soils and further stimulated under FTC conditions. Additionally, the nutrient-amended treatment under the FTC regime enhanced bacterial groups with known biodegradation potential and was efficient in removing hydrocarbons of diesel oil. The experimental design, rates of bacterial succession, and level of hydrocarbon transformation can be considered as a baseline for further studies aimed at improving bioremediation strategies in environments affected by FTC regimes.

Lysobacter penaei sp. nov., isolated from intestinal content of a Pacific white shrimp (Penaeus vannamei)

The polyphasic taxonomic approach was used to characterize a novel bacteria strain, designated SG-8^T, which was isolated from intestinal content of a Pacific white shrimp (Penaeus vannamei). Cells were Gram-stain-negative, aerobic, non-gliding rods. Growth occurred at 10-45 °C (optimum, 20-30 °C), pH 5.0-10.0 (optimum, 6.0-7.0) and in 0-6.0 % (w/v) NaCl (optimum, 0-4.0 %). The 16S rRNA gene sequence of strain SG-8^T showed the highest sequence similarity to Lysobacter maris KMU-14^T (98.6 %). On phylogenetic trees, strain SG-8^T formed a stable cluster with Lysobacter maris KMU-14^T, Lysobacter alkalisoli SJ-36^T, Lysobacter spongiae 119BY6-57^T and Lysobacter aestuarii S2-C^T. The average nucleotide identity and digital DNA-DNA hybridization values between strain SG-8^T and the four reference type strains listed above were 83.3, 82.3, 83.5, 83.3% and 22.8, 22.7, 22.7, 22.9 %, respectively. The major fatty acids (>5 %) were iso-C_15 : 0, summed feature 9 (iso-C_17 : 1  ω9c and/or 10-methyl C_16 : 0), iso-C_16 : 0, summed feature 3 (C_16 : 1  ω6c and/or C_16 : 1  ω7c), iso-C_17 : 0, iso-C_11 : 0 3OH and iso-C_11 : 0. Ubiquinone-8 (Q-8) was the only respiratory quinone. The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The DNA G+C content was 68.8 mol%. Based on the results of genomic, phylogenetic, phenotypic and chemotaxonomic analyses, strain SG-8^T represents a novel species of the genus Lysobacter, for which the name Lysobacter penaei sp. nov. is proposed. The type strain is SG-8^T (=GDMCC 1.1817^T=KACC 21942^T).

Arenibacter arenosicollis sp. nov., isolated from a sand dune

A Gram-stain-negative, aerobic, non-spore-forming, non-motile and rod-shaped bacterial strain, designated BSSL-BM3^T, was isolated from sand collected from a dune near the Yellow Sea, Republic of Korea, and subjected to a polyphasic taxonomic study. The neighbour-joining phylogenetic tree of 16S rRNA gene sequences showed that strain BSSL-BM3^T fell within the clade comprising the type strains of Arenibacter species. Strain BSSL-BM3^T exhibited 16S rRNA gene sequence similarity values of 98.0-99.0 % to the type strains of Arenibacter catalasegens, Arenibacter hampyeongensis, Arenibacter echinorum, Arenibacter palladensis and Arenibacter troitsensis and of 94.2-96.7 % to the type strains of the other Arenibacter species. The averagenucleotide identity and digitalDNA-DNA hybridization values between strain BSSL-BM3^T and the type strains of A. catalasegens, A. hampyeongensis, A. echinorum, A. palladensis and A. troitsensis were 82.2-88.8 % and 25.0-36.5 %, respectively. The DNA G+C content of strain BSSL-BM3^T from genomic sequence data was 38.75 mol%. Strain BSSL-BM3^T contained MK-6 as the predominant menaquinone and iso-C_17 : 0 3-OH, summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c) and iso-C_15 : 1 G as the major fatty acids. The major polar lipids of strain BSSL-BM3^T were phosphatidylethanolamine and two unidentified lipids. Distinguishing phenotypic properties, along with the phylogenetic and genetic distinctiveness, revealed that strain BSSL-BM3^T is separated from recognized Arenibacter species. On the basis of the data presented here, strain BSSL-BM3^T is considered to represent a novel species of the genus Arenibacter, for which the name Arenibacter arenosicollis sp. nov. is proposed. The type strain is BSSL-BM3^T (=KACC 21632^T=NBRC 114502^T).

Arenibacter amylolyticus sp. nov., an amylase-producing bacterium of the family Flavobacteriaceae isolated from marine water in India

A novel Gram-stain-negative, curved rod-shaped, 0.5-0.7 µm wide and 3.0-10.0 µm long, non-motile bacterium, designated strain AK53^T, was isolated from a 5 m depth water sample collected from the Bay of Bengal, Visakhapatnam, India. Colonies on marine agar were circular, small, dark orange, shiny, smooth, translucent, flat, with an entire margin. The major fatty acids included iso-C_15 : 0, iso-C_15 : 0 3OH, anteiso-C_15 : 0, iso-C_15 : 1 G, iso-C_17 : 0 3OH and summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c and/or iso-C_15 : 0-2OH). Polar lipids included phosphatidylethanolamine and five unidentified lipids. The DNA G+C content of the strain AK53^T was found to be 40.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain AK53^T was closely related to Arenibacter latericius KMM 426^T and Arenibacter certesii KMM3941^T (pair-wise sequence similarity of 99.17 and 98.89 %, respectively), forming a distinct branch within the genus Arenibacter and clustering with A. latericius. Strain AK53^T shared average nucleotide identity (ANIb, based on blast) of 78.07 and 77.44 % with A. latericius JCM 13508^T and A. certesii JCM 13507^T, respectively. Based on the observed phenotypic, chemotaxonomic characteristics and phylogenetic analysis, strain AK53^T is described in this study as representing a novel species in the genus Arenibacter, for which the name Arenibacter amylolyticus sp. nov. is proposed. The type strain of Arenibacter amylolyticus is AK53^T (=MTCC 12004^T= JCM 19206^T=KCTC 62553^T).

Arenibacter lacus sp. nov., Isolated from Chilika Lagoon, India

A shiny dark yellow pigmented, Gram-stain-negative, rod-shaped, non-motile bacterium, designated as strain JC631^T, was isolated from the sediment ecosystem of Chilika lagoon, India. Strain JC631^T tolerates up to pH 10 and NaCl up to 3% (w/v). MK6 is the only respiratory quinone. Predominant (> 10%) cellular fatty acids are anteiso-C_11:0, anteiso-C_13:0, and anteiso-C_15:0. Major polar lipids are phosphatidylethanolamine, phosphatidylcholine, a few unidentified phospholipids, and a few unidentified aminolipids. 16S rRNA gene sequencing showed that strain JC631^T shared the highest sequence identity (98.7%) with Arenibacter latericius KMM 426^T followed by Arenibacter certesii CCUG 48006^T (98.6%) and other members of the genus Arenibacter (< 97%). The genome size of strain JC631^T is 4.16 Mb with a GC content of 40.8 mol%. Strain JC631^T has ANI scores of 78.3% and 78.1%; dDDH values of 22.2% and 21.8%, respectively, with the type strains of A. latericius and A. certesii. The genomic distinction is well supported by chemotaxonomic characteristics and differential physiological properties. This supports strain JC631^T to be described as a new species of the genus Arenibacter, named as Arenibacter lacus sp. nov. The type strain is JC631^T (= KCTC 72002^T = NBRC 114071^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.