Pengzhenrongella frigida sp. nov., isolated from a glacier.

A Gram-stain-positive, rod-shaped bacterium, designated as HLT2-17T, was isolated from soil sample taken from the Hailuogou glacier in Sichuan province, PR China. Strain HLT2-17T was capable of growing at 4-25°C and in NaCl concentrations ranging from 0 to 2% (w/v). The highest level of 16S rRNA gene sequence similarity was observed with Pengzhenrongella phosphoraccumulans M0-14T (98.3 %) and Pengzhenrongella sicca LRZ-2T (98.2 %). The average nucleotide identity and digital DNA-DNA hybridization values between strain HLT2-17T and its closest relatives, P. phosphoraccumulans M0-14T and P. sicca LRZ-2T, were 80.0-84.0 % and 23.3-27.7 %, respectively. Phylogenomic analysis indicated that strain HLT2-17T clustered together with strains P. phosphoraccumulans M0-14T and P. sicca LRZ-2T. Strain HLT2-17T contained C16 : 0 and anteiso-C15 : 0 as the major fatty acids, and MK-9(H4) as the menaquinone. Therefore, based on a polyphasic approach, we propose that strain HLT2-17T (=CGMCC 1.11116T= NBRC 110443T) represents a novel species of the genus Pengzhenrongella and suggest the name Pengzhenrongella frigida sp. nov.

Identification of Flavobacterium algoritolerans sp. nov. and Flavobacterium yafengii sp. nov., two novel members of the genus Flavobacterium.

Six psychrotolerant, Gram-stain-negative, aerobic bacterial strains, designated as LB1P51T, LB2P87T, LB2P84, LB3P48, LB3R18 and XS2P67, were isolated from glaciers on the Tibetan Plateau, PR China. The results of 16S rRNA gene analysis confirmed their classification within the genus Flavobacterium. Strain LB2P87T displayed the highest sequence similarity to Flavobacterium sinopsychrotolerans 0533T (98.18 %), while strain LB1P51T exhibited the highest sequence similarity to Flavobacterium glaciei CGMCC 1.5380T (98.15 %). Strains LB2P87T and LB1P51T had genome sizes of 3.8 and 3.9 Mb, respectively, with DNA G+C contents of 34.2 and 34.1 %, respectively. Pairwise average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) calculations revealed that these strains represented two distinct species within the genus Flavobacterium. The results of phylogenomic analysis using 606 core genes indicated that the six strains formed a distinct clade and were most closely related to F. glaciei CGMCC 1.5380T. The ANI and dDDH values between the two species and other members of the genus Flavobacterium were below 90.3 and 40.1 %, respectively. Genome relatedness, the results of phylogenomic analysis and phenotypic characteristics collectively support the proposal of two novel species of the genus Flavobacterium: Flavobacterium algoritolerans sp. nov. (LB1P51T = CGMCC 1.11237T = NBRC 114813T) and Flavobacterium yafengii sp. nov. (LB2P87T = CGMCC 1.11249T = NBRC 114814T).

Analysis of Microbial Diversity in South Shetland Islands and Antarctic Peninsula Soils Based on Illumina High-Throughput Sequencing and Cultivation-Dependent Techniques.

To assess the diversity of bacterial taxa in Antarctic soils and obtain novel microbial resources, 15 samples from 3 sampling sites (DIS5, GWS7, FPS10) of South Shetland Islands and 2 sampling sites (APS18, CIS17) of Antarctic Peninsula were collected. High-throughput sequencing (HTS) of 16S rRNA genes within these samples was conducted on an Illumina Miseq platform. A total of 140,303 16S rRNA gene reads comprising 802 operational taxonomic units (OTUs) were obtained. After taxonomic classification, 25 phyla, 196 genera, and a high proportion of unidentified taxa were detected, among which seven phyla and 99 genera were firstly detected in Antarctica. The bacterial communities were dominated by Actinomycetota (40.40%), Pseudomonadota (17.14%), Bacteroidota (10.55%) and Chloroflexota (10.26%). Based on the HTS analyses, cultivation-dependent techniques were optimized to identify the cultivable members. A total of 30 different genera including 91 strains were obtained, the majority of which has previously been reported from Antarctica. However, for the genera Microterricola, Dyadobacter, Filibacter, Duganella, Ensifer, Antarcticirhabdus and Microvirga, this is the first report in Antarctica. In addition, seven strains represented novel taxa, two of which were psychropoilic and could be valuable resources for further research of cold-adaptability and their ecological significance in Antarctica.

Antarcticirhabdus aurantiaca gen. nov., sp. nov., isolated from Antarctic gravel soil.

Strain R10T was isolated from a gravel soil sample obtained from Deception Island, Antarctica. The isolate was a Gram-stain-negative, strictly aerobic, motile, short-rod-shaped bacterium, and its colonies were orange yellow in colour. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain R10T belonged to the family Aurantimonadaceae and shared highest sequence similarity with Jiella aquimaris LZB041T (96.3 % sequence similarity), Aurantimonas aggregata R14M6T (96.0 %) and Aureimonas frigidaquae JCM 14755T (96.0 %). Phylogenetic analysis showed that strain R10T affiliated with members of the family Aurantimonadaceae and represented an independent lineage. Growth occurred at 10-37 °C (optimum, 28-32 °C), up to 1.0 % (w/v) NaCl (optimum, 0 %) and pH 5.5-9.0 (optimum, pH 7.0). The major respiratory quinone of strain R10T was Q-10. Its major fatty acids were C18 : 1 ω7c and C16 : 0. The polar lipid profile of strain R10T comprised diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, two unknown phospholipids and two unknown aminophospholipids. The genome of strain R10T was 5.92 Mbp with a G+C content of 69.1 % based on total genome calculations. Average nucleotide identity (ANI) values between R10T and other related species of the family Aurantimonadaceae were found to be low (ANIm <87.0 %, ANIb <75.0 % and OrthoANIu <77.0 %). Furthermore, digital DNA-DNA hybridization (dDDH) and average amino acid identity (AAI) values between strain R10T and the closely related species ranged from 19.5-20.6% and from 60.6-64.0 %, respectively. Based on the results of our phylogenetic, phenotypic, genotypic and chemotaxonomic analyses, it is concluded that strain R10T represents a novel genus and species of the family Aurantimonadaceae, for which the name Antarcticirhabdus aurantiaca gen. nov., sp. nov. is proposed. The type strain is R10T (=KCTC 72466T=CGMCC 1.17155T).

Diversity of the genus Cryobacterium and proposal of 19 novel species isolated from glaciers.

The bacterial genus Cryobacterium includes at present 14 species that live in cryospheric environments. In this study, we analyzed 101 genomes of Cryobacterium with pure cultures obtained from GenBank. They could be classified into 44 species based on average nucleotide identity (ANI) analysis, showing the diversity of Cryobacterium. Among these, 19 strains in our laboratory were isolated from the glacier samples in China. The pairwise ANI values of these 19 strains and known species were <95%, indicating that they represented 19 novel species. The comparative genomic analysis showed significant differences in gene content between the two groups with a maximum growth temperature (T max) of ≤ 20°C and a T max of >20°C. A comprehensive and robust phylogenetic tree, including 14 known species and 19 novel species, was constructed and showed five phylogenetic branches based on 265 concatenated single-copy gene sequences. The T max parameter had a strong phylogenetic signal, indicating that the temperature adaptation of Cryobacterium was largely through vertical transfer rather than horizontal gene transfer and was affected by selection. Furthermore, using polyphasic taxonomy combined with phylogenomic analysis, we proposed 19 novel species of the genus Cryobacterium by the following 19 names: Cryobacterium serini sp. nov., Cryobacterium lactosi sp. nov., Cryobacterium gelidum sp. nov., Cryobacterium suzukii sp. nov., Cryobacterium fucosi sp. nov., Cryobacterium frigoriphilum sp. nov., Cryobacterium cryoconiti sp. nov., Cryobacterium lyxosi sp. nov., Cryobacterium sinapicolor sp. nov., Cryobacterium sandaracinum sp. nov., Cryobacterium cheniae sp. nov., Cryobacterium shii sp. nov., Cryobacterium glucosi sp. nov., Cryobacterium algoritolerans sp. nov., Cryobacterium mannosilyticum sp. nov., Cryobacterium adonitolivorans sp. nov., Cryobacterium algoricola sp. nov., Cryobacterium tagatosivorans sp. nov., and Cryobacterium glaciale sp. nov. Overall, the taxonomy and genomic analysis can improve our knowledge of phenotypic diversity, genetic diversity, and evolutionary characteristics of Cryobacterium.

Flavobacterium frigoritolerans sp. nov. and Flavobacterium shii sp. nov., isolated from glaciers on the Tibetan Plateau.

The genus Flavobacterium belongs to the family Flavobacteriaceae and its members are widely distributed in the environment. Taxonomic descriptions of strains LS1R47T and LS1R49T isolated from the Laigu glacier on the Tibetan Plateau, China, are presented in this study. Both strains were psychrotolerant, Gram-stain-negative, aerobic and rod-shaped. The comparative analysis of 16S rRNA gene sequences showed that strain LS1R47T was closest to Flavobacterium bizetiae CIP 105534T (98.90 %) and strain LS1R49T was closest to Flavobacterium collinsii 983-08T (98.73 %). The 16S rRNA gene sequence similarity, average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two novel isolates were 99.4, 86.0 and 30.9 %, respectively. The ANI and dDDH values between strains LS1R47T and LS1R49T and their closely relatives were below 87.6 and 33.3 %, respectively. Phylogenomic analysis showed that the two strains cluster together with Flavobacterium hydatis ATCC 29551T. Both strains contained MK-6 as sole quinone, phosphatidylethanolamine as the principal polar lipid, and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1 ω7c), iso-C15 : 0 3-OH, C15 : 0 3-OH and iso-C17 : 0 3-OH as the main fatty acids. These results indicated that strains LS1R47T and LS1R49T represented two novel species within the genus Flavobacterium. Therefore, we propose two novel species, Flavobacterium frigoritolerans sp. nov. (LS1R47T=CGMCC 1.11577T=NBRC 113654T) and Flavobacterium shii sp. nov. (LS1R49T=CGMCC 1.11581T=NBRC 113652T).

Genomic and Epidemiological Features of COVID-19 in the Novosibirsk Region during the Beginning of the Pandemic.

In this retrospective, single-center study, we conducted an analysis of 13,699 samples from different individuals obtained from the Federal Research Center of Fundamental and Translational Medicine, from 1 April to 30 May 2020 in Novosibirsk region (population 2.8 million people). We identified 6.49% positive for SARS-CoV-2 cases out of the total number of diagnostic tests, and 42% of them were from asymptomatic people. We also detected two asymptomatic people, who had no confirmed contact with patients with COVID-19. The highest percentage of positive samples was observed in the 80+ group (16.3%), while among the children and adults it did not exceed 8%. Among all the people tested, 2423 came from a total of 80 different destinations and only 27 of them were positive for SARS-CoV-2. Out of all the positive samples, 15 were taken for SARS-CoV-2 sequencing. According to the analysis of the genome sequences, the SARS-CoV-2 variants isolated in the Novosibirsk region at the beginning of the pandemic belonged to three phylogenetic lineages according to the Pangolin classification: B.1, B.1.1, and B.1.1.129. All Novosibirsk isolates contained the D614G substitution in the Spike protein, two isolates werecharacterized by an additional M153T mutation, and one isolate wascharacterized by the L5F mutation.

Hymenobacter terricola sp. nov., isolated from Antarctic soil.

Strain 3F2T was isolated from a soil sample obtained from the surface of Deception Island, Antarctica. The isolate was a Gram-stain-negative, aerobic, non-motile, rod-shaped bacterium, and its colonies were red to pink in colour. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 3F2T belonged to the genus Hymenobacter, family Hymenobacteraceae and was most closely related to Hymenobacter sedentarius DG5BT (97.0% sequence similarity), Hymenobacter soli PB17T (96.9%), Hymenobacter terrae DG7AT (96.8%) and Hymenobacter rufus S1-2-2-6T (96.5%). Growth occurred at 4-20 °C (optimum, 10 °C), up to 1.0 % (w/v) NaCl (optimum, 0%) and pH 6.0-8.0 (optimum, pH 7.0). The chemotaxonomic characteristics of strain 3F2T, which had MK-7 as its predominant menaquinone and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), iso-C15:0, anteiso-C15:0 and C16:1 ω5c as its major fatty acids, were consistent with classification in the genus Hymenobacter. The polar lipid profile of strain 3F2T comprised phosphatidylethanolamine, two unidentified aminolipids, two unidentified aminophospholipids and three unidentified polar lipids. The genome of strain 3F2T was 6.56 Mbp with a G+C content of 61.5 mol%. Average nucleotide identity (ANI) values between 3F2T and the other species of the genus Hymenobacter were found to be low (ANIm <87.0%, ANIb <82.0% and OrthoANIu <83.0%). Furthermore, digital DNA-DNA hybridization and average amino acid identity values between strain 3F2T and the closely related species ranged from 20.0 to 26.3% and from 64.0 to 81.1 %, respectively. Based on the results of our phylogenetic, phenotypic, genotypic and chemotaxonomic analyses, it is concluded that strain 3F2T represents a novel species within the genus Hymenobacter, for which the name Hymenobacter terricola sp. nov. is proposed. The type strain is 3F2T (=KCTC 72468T=CGMCC 1.13716T).

Mucilaginibacter aurantiaciroseus sp. nov. and Mucilaginibacter flavidus sp. nov., isolated from Renlongba glacier on the Tibetan Plateau.

Strains RB4R14T and RT5R15T, two Gram-stain-negative, aerobic, rod-shaped, non-motile bacteria, were isolated from ice and cryoconite of Renlongba glacier, respectively, on the Tibetan Plateau, PR China. The results of phylogenetic analysis based on 16S rRNA genes indicated that strains RB4R14T and RT5R15T belonged to the genus Mucilaginibacter with the highest similarities to Mucilaginibacter rigui WPCB133T (98.78 %) and Mucilaginibacter xinganensis BJC16-A31T (97.64 %), respectively. The genomic DNA G+C contents of strains RB4R14T and RT5R15T were 42.8 and 43.1 mol%, respectively. The digital DNA-DNA hybridization values between strains RB4R14T, RT5R15T and their close relatives were below 31.9 and 17.4 %, respectively. The average nucleotide identity values between the two novel strains and their close relatives were 79.5-82.0 and 77.9-79.3 % respectively, indicating the novelty of the two isolates at a species level. The two novel strains contained MK-7 as the major menaquinone, and summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c), iso-C15 : 0 and iso-C17 : 0-3OH as the major fatty acids. The major polar lipid of the two novel strains were phosphatidylethanolamine. Based on phenotypic, chemotaxonomic and phylogenetic results, we propose two novel species, Mucilaginibacter aurantiaciroseus sp. nov. (RB4R14T=CGMCC 1.11911T=NBRC 114020T) and Mucilaginibacter flavidus sp. nov. (RT5R15T=CGMCC 1.23117T=NBRC 113930T).

The monkey microbial biobank brings previously uncultivated bioresources for nonhuman primate and human gut microbiomes.

Nonhuman primates (NHPs) such as monkeys are the closest living relatives to humans and are the best available models for causative studies of human health and diseases. Gut microbiomes are intensively involved in host health. In this study, by large-scale cultivation of microbes from fecal samples of monkeys, we obtained previously uncultured bacterial species and constructed a Macaca fascicularis Gut Microbial Biobank (MfGMB). The MfGMB consisted of 250 strains that represent 97 species of 63 genera, 25 families, and 4 phyla. The information of the 250 strains and the genomes of 97 cultured species are publicly accessible. The MfGMB represented nearly 50% of core gut microbial compositions at the genus level and covered over 80% of the KO-based known gut microbiome functions of M. fascicularis. Data mining showed that the bacterial species in the MfGMB were prevalent not only in NHPs gut microbiomes but also in human gut microbiomes. This study will help the understanding and future investigations on how gut microbiomes interact with their mammalian hosts.

Arthrobacter cheniae and Arthrobacter frigidicola sp. nov., isolated from a glacier.

Two Gram-stain-positive, aerobic, rod-shaped, pink and light pink colony-forming bacteria, designated as Hz2T and MDT2-14T, respectively, were isolated from glacier cryoconite samples. Comparisons based on 16S rRNA gene sequences showed that strains Hz2T and MDT2-14T take Arthrobacter bussei KR32T and Arthrobacter zhaoguopingii J391T as their closest neighbours, respectively. The average nucleotide identity values between the two novel strains and their closest relatives were 83.56 and 93.06 %, respectively. The two strains contain MK-9(H2) as their predominant menaquinone. The polar lipids of both strains were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and an unidentified glycolipid. The major fatty acids of strain Hz2T were anteiso-C15 : 0, summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c) and iso-C15 : 0, while the major fatty acids of strain MDT2-14T were anteiso-C15 : 0 and anteiso-C17 : 0. Based on these data, we propose two novel species, Arthrobacter cheniae sp. nov. (Hz2T = CGMCC 1.9262T=NBRC 113086T) and Arthrobacter frigidicola sp. nov. (MDT2-14T=CGMCC 1.9882T=NBRC 113089T).

Glacieibacterium frigidum gen. nov., sp. nov., a novel member of the family Sphingosinicellaceae isolated from a glacier.

A novel Gram-stain-negative, rod-shaped, yellow bacterium, designated as LB1R16T, was isolated from the Laigu glacier on the Tibetan Plateau, PR China. Strain LB1R16T was catalase-positive, oxidase-negative and grew at 0-28 °C, pH 6.0-8.0 and in the absence of NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain LB1R16T belongs to the family Sphingosinicellaceae but formed an independent lineage. The highest level of 16S rRNA gene sequence similarities were found to Polymorphobacter arshaanensis DJ1R-1T (95.24 %), Sphingoaurantiacus capsulatus YLT33T (94.78 %) and Sandarakinorhabdus limnophila DSM 17366T (94.67 %). The genomic DNA G+C content was 68.8 mol%. The main cellular fatty acids were summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c), summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c), C16 : 0 and C12 : 0-OH. The respiratory quinone was ubiquinone-10. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, one sphingoglycolipid, one unidentified aminolipid, one unidentified phospholipid and two unidentified polar lipids, which were different from the type strains of Polymorphobacter arshaanensis, Sphingoaurantiacus capsulatus and Sandarakinorhabdus limnophila. Based on a polyphasic approach, a novel species of a new genus, Glacieibacterium frigidum gen. nov., sp. nov., within the family Sphingosinicellaceae is proposed. The type strain is LB1R16T (=CGMCC 1.11941T=NBRC 113873T).

Flavobacterium franklandianum sp. nov. and Flavobacterium gawalongense sp. nov., isolated from glaciers on the Tibetan Plateau.

The genus Flavobacterium (family Flavobacteriaceae) can be found in diverse environments. In this study, seven novel strains were isolated from glaciers in PR China and subjected to taxonomic research. Phylogenetic analyses based on the 16S rRNA gene revealed that the strains belonged to the genus Flavobacterium. None of the seven strains grew at temperatures above 22 °C, indicating that they are psychrophilic. Furthermore, the average nucleotide identity (ANI) values of the seven strains were calculated and indicated that they represented two novel species in Flavobacterium. Strain LB3P56T was most closely related to Flavobacterium soyangense IMCC26223T (97.70 %) and strain GSP16T was most closely related to Flavobacterium sinopsychrotolerans 0533T (98.03 %). The ANI values between the two Flavobacterium strains and their closest relatives were less than 83.47 %, which was much lower than the threshold for species delineation of 95-96 %. Therefore, we propose two novel species, Flavobacterium franklandianum sp. nov. (LB3P56T=CGMCC 1.11934T=NBRC 113651T) and Flavobacterium gawalongense sp. nov. (GSP16T=CGMCC 1.24642T=NBRC 113664T).

Enlightening the taxonomy darkness of human gut microbiomes with a cultured biobank.

BACKGROUND: In gut microbiome studies, the cultured gut microbial resource plays essential roles, such as helping to unravel gut microbial functions and host-microbe interactions. Although several major studies have been performed to elucidate the cultured human gut microbiota, up to 70% of the Unified Human Gastrointestinal Genome species have not been cultured to date. Large-scale gut microbial isolation and identification as well as availability to the public are imperative for gut microbial studies and further characterizing human gut microbial functions. RESULTS: In this study, we constructed a human Gut Microbial Biobank (hGMB; homepage: hgmb.nmdc.cn ) through the cultivation of 10,558 isolates from 31 sample mixtures of 239 fresh fecal samples from healthy Chinese volunteers, and deposited 1170 strains representing 400 different species in culture collections of the International Depository Authority for long-term preservation and public access worldwide. Following the rules of the International Code of Nomenclature of Prokaryotes, 102 new species were characterized and denominated, while 28 new genera and 3 new families were proposed. hGMB represented over 80% of the common and dominant human gut microbial genera and species characterized from global human gut 16S rRNA gene amplicon data (n = 11,647) and cultured 24 "most-wanted" and "medium priority" taxa proposed by the Human Microbiome Project. We in total sequenced 115 genomes representing 102 novel taxa and 13 previously known species. Further in silico analysis revealed that the newly sequenced hGMB genomes represented 22 previously uncultured species in the Unified Human Gastrointestinal Genome (UHGG) and contributed 24 representatives of potentially "dark taxa" that had not been discovered by UHGG. The nonredundant gene catalogs generated from the hGMB genomes covered over 50% of the functionally known genes (KEGG orthologs) in the largest global human gut gene catalogs and approximately 10% of the "most wanted" functionally unknown proteins in the FUnkFams database. CONCLUSIONS: A publicly accessible human Gut Microbial Biobank (hGMB) was established that contained 1170 strains and represents 400 human gut microbial species. hGMB expands the gut microbial resources and genomic repository by adding 102 novel species, 28 new genera, 3 new families, and 115 new genomes of human gut microbes. Video abstract.

Planococcus soli sp. nov., isolated from antarctic soil.

A novel bacterial strain, designated C23T, was isolated from a soil sample obtained from King George Island, Antarctica. Phenotypic, phylogenetic, chemotaxonomic and molecular analyses were performed on the new isolate. Strain C23T formed orange colonies on agar plates and was Gram-stain-positive. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain C23T was a member of the genus Planococcus and was closely related to Planococcus salinarum DSM 23802T (98.5% sequence similarity), Planococcus halotolerans SCU63T (98.3%), Planomicrobium okeanokoites IFO 12526T (98.3%), Planococcus donghaensis DSM 22276T (98.3%) and Planococcus maitriensisi S1T (98.2%). This organism grew at 2-38 °C (optimum, 25-30 °C), pH 6.0-12.0 (optimum, pH 7.5) and 0-14% (w/v) NaCl (optimum, 2%). The predominant menaquinone was MK-8. The major cellular fatty acids were anteiso-C15:0, iso-C14:0 and C16:1 ω7c alcohol. The whole genome DNA of C23T was deposited in the GenBank database under accession number WXYN00000000. According to the whole genome, the DNA G + C content of strain C23T was determined to be 46.8 mol%; the average nucleotide identity (ANI) of strain C23T and P. salinarum DSM 23802T, P. halotolerans SCU63T, P. okeanokoites IFO 12526T, P. donghaensis DSM 22276T and P. maitriensis S1T were 74.1%, 74.3%, 74.1%, 78.8 and 73.6%; the digital DNA-DNA hybridization (dDDH) values between strain C23T and the five closely related species were 19.7%, 19.6%, 19.5%, 22.4 and 18.6%; the average amino acid identity (AAI) values between strain C23T and the five closely related species were 73.9%, 74.5%, 74.4%, 84.6 and 74.5%. All data were below the threshold range for species determination. Based on the polyphasic taxonomic study, we considered that strain C23T represented a novel species of the genus Planococcus for which the name Planococcus soli sp. nov. is proposed. The type strain is C23T (= KCTC 33644T = CGMCC 1.15115T).

Light stimulates anoxic and oligotrophic growth of glacial Flavobacterium strains that produce zeaxanthin.

Bacteria that inhabit glaciers usually produce carotenoids. Here, we report that a group of zeaxanthin-producing glacial Flavobacterium exhibited light-promoted growth. Of the tested 47 strains, 45 showed increased growths but two died under illumination at 50 µmol photon m-2 s-1. Light stimulation occurred mainly in either anoxic or nutrient-poor cultures, while the same levels of light promotion were found for that grown at 14 and 7 °C. Pigment assays identified overrepresentative zeaxanthin but trace retinal in the light promoted 45 strains, while flexirubin was exclusively in the light-lethal two. Genomic analysis revealed the gene cluster for zeaxanthin synthesis in the 45 strains, in which 37 strains also harbored the proteorhodopsin gene prd. Transcriptomic analysis found that light-induced expressions of both the zeaxanthin synthesis and proteorhodopsin genes. Whereas, deletion of the prd gene in one strain did not diminish light promotion, inhibition of zeaxanthin synthesis did. In comparison, no light promotion was determined in a glacier Cryobacterium luteum that produced a non-zeaxanthin-type carotenoid. Therefore, light stimulation on the glacial Flavobacterium is mostly likely related to zeaxanthin, which could provide better photoprotection and sustain membrane integrity for the organisms living in cold environments.

Mucilaginibacter glaciei sp. nov. and Mucilaginibacter pankratovii sp. nov., isolated from a glacier on the Tibetan Plateau.

Two Gram-stain-negative, aerobic, rod-shaped, non-motile, bacterial strains, designated as ZB1P21T and ZT4R22T, were isolated from ice and cryoconite samples collected from Zepu glacier on the Tibetan Plateau, PR China. The phylogenetic analysis of 16S rRNA gene showed that the two strains belong to the genus Mucilaginibacter. Strain ZB1P21T showed the highest similarity to Mucilaginibacter rigui WPCB133T (97.35 %), while strain ZT4R22T showed the highest similarity to Mucilaginibacter gilvus F01003T (99.11 %). The average nucleotide identity values between the two novel strains and their closest relatives were 79.42 and 85.72 % respectively. The two novel strains contained MK-7 as the major menaquinone, and summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c), iso-C15:0, iso-C17 : 03-OH and C16 : 1 ω5c as the major fatty acids. The major polar lipid of the two novel strains were phosphatidylethanolamine. Based on these data, we propose two novel species, Mucilaginibacter glaciei sp. nov. (ZB1P21T=CGMCC 1.23981T=NBRC 113932T) and Mucilaginibacter pankratovii sp. nov. (ZT4R22T=CGMCC 1.23487T=NBRC 113931T).

Flavobacterium restrictum sp. nov., Flavobacterium rhamnosiphilum sp. nov., and Flavobacterium zepuense sp. nov. isolated from glaciers.

Three strains, designated as LB1R34T, LB3P52T and ZT4R6T, were isolated from glaciers located on the Tibetan Plateau, PR China. The strains were Gram-stain-negative, aerobic, rod-shaped, non-motile and yellow. Phylogenetic analysis based on the 16S rRNA gene and genomic sequences indicated that they were related to the members of the genus Flavobacterium. The 16S rRNA gene sequences similarities between the three strains were 92.31-96.93 %. The average nucleotide identity values and digital DNA-DNA hybridization values between these three strains and their closest relatives were 76.80-91.33 % and 21.3-44.2 %, respectively. LB1R34T, LB3P52T and ZT4R6T contained MK-6 as the major menaquinone, summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c) and iso-C15 : 0 as the major fatty acids. Phosphatidylethanolamine was present in their polar lipids profiles. On the basis of the phenotypic characteristics, he results of phylogenetic analysis and genotypic data, three novel species, Flavobacterium restrictum sp. nov. (type strain=LB1 R34T=CGMCC 1.11493T=NBRC 113650T), Flavobacterium rhamnosiphilum sp. nov. (type strain=LB3 P52T=CGMCC 1.11446T=NBRC 113776T) and Flavobacterium zepuense sp. nov. (type strain=ZT4 R6T=CGMCC 1.11919T=NBRC 113653T) are proposed.