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Genome analysis is one of the main criteria for description of new taxa. Availability of genome sequences for all the actinobacteria with a valid nomenclature will, however, require another decade’s works of sequencing. This paper describes the rearrangement of the higher taxonomic ranks of the members of the phylum ‘ Actinobacteria ’, using the phylogeny of 16S rRNA gene sequences and supported by the phylogeny of the available genome sequences. Based on the refined phylogeny of the 16S rRNA gene sequences, we could arrange all the members of the 425 genera of the phylum ‘ Actinobacteria ’ with validly published names currently in use into six classes, 46 orders and 79 families, including 16 new orders and 10 new families. The order Micrococcales Prévot 1940 (Approved Lists 1980) emend. Nouioui et al. 2018 is now split into 11 monophyletic orders: the emended order Micrococcales and ten proposed new orders Aquipuribacterales , Beutenbergiales , Bogoriellales , Brevibacteriales , Cellulomonadales , Demequinales , Dermabacterales , Dermatophilales , Microbacteriales and Ruaniales . Further, the class ‘ Actinobacteria ’ Stackebrandt et al. 1997 emend. Nouioui et al. 2018 was described without any nomenclature type, and therefore the name ‘ Actinobacteria ’ is deemed illegitimate. In accordance to Rule 8 of the International Code of Nomenclature of Prokaryotes, Parker et al. 2019, we proposed the name Actinomycetia which is formed by using the stem of the name Actinomycetales Buchanan 1917 (Approved Lists 1980) emend. Zhi et al. 2009, to replace the name ‘ Actinobacteria ’. The nomenclature type of the proposed new class Actinomycetia is the order Actinomycetales Buchanan 1917 (Approved Lists 1980) emend. Zhi et al. 2009.

A novel proteobacterial strain designated SYSU H10001T was isolated from a soil sample collected from plateau meadow in Hongyuan county, Sichuan province, south-western China. The taxonomic position of the strain was investigated using a polyphasic approach. On the basis of 16S rRNA gene sequence similarities and phylogenetic analysis, strain SYSU H10001T was most closely related to Lysobacter soli KCTC 22011T (98.6%, sequence similarity) and Lysobacter panacisoli JCM 19212T (98.2%). The prediction result of secondary metabolites based on genome shown that the strain SYSU H10001T contained 3 clusters of bacteriocins, 1 cluster of non-ribosomal peptide synthetase, 1 cluster of type 1 polyketide synthase and 1 cluster of arylpolyene. In addition, the major isoprenoid quinone was Q-8 and the major fatty acids were identified as iso-C15:0, iso-C17:0 and Summed feature 9. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and three unidentified phospholipids. The genomic DNA G + C content of strain SYSU H10001T was 66.5% (genome). On the basis of phenotypic, genotypic and phylogenetic data, strain SYSU H10001T represents a novel species of the genus Lysobacter, for which the name Lysobacter prati sp. nov. is proposed. The type strain is SYSU H10001T (= KCTC 72062T = CGMCC 1.16662T).

A novel actinobacterial strain, designated SYSU K10008T, was isolated from a soil sample collected from a karst cave in Xingyi County, Guizhou Province, south-western PR China. The taxonomic position of the strain was investigated by using a polyphasic approach. Cells of the strain were aerobic, Gram-stain-positive and non-motile. On the basis of 16S rRNA gene sequence similarities and the results of phylogenetic analysis, strain SYSU K10008T was most closely related to Streptomyces cyaneus CGMCC 4.1671T, and shared the highest sequence identity of 98.3 % based on the NCBI database. In addition, ll-diaminopimelic acid was the diagnostic diamino acid in cell-wall peptidoglycan. The whole-cell sugars were glucose and rhamnose. The major isoprenoid quinone was MK-9(H6), while the major fatty acids (>10 %) were C16 : 0, iso-C16 : 0, anteiso-C15 : 0 and summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c). The polar lipids contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside and one unidentified lipid. The genomic DNA G+C content of strain SYSU K10008T was 70.5 mol%. On the basis of phenotypic, genotypic and phylogenetic data, strain SYSU K10008T represents a novel species of the genus Streptomyces , for which the name Streptomyces cavernae sp. nov. is proposed. The type strain is SYSU K10008T (=KCTC 39850T=DSM 104115T).

Three closely related, facultative anaerobic, Gram-stain-negative, twitching motile, short rod-shaped, non-endospore-forming, moderately thermophilic bacteria, designated strains SYSU G05001T, SYSU G05003 and SYSU G05004, were isolated from a hot spring microbial mat, collected from Rehai National Park, Tengchong, Yunnan Province, south-western China. The results of phylogenetic analysis based on the 16S rRNA gene sequences indicated that these three strains were closely related to Thermus scotoductus SE-1T (97.97, 98.18, 97.90 % sequence similarity). Whole genome sequencing and polyphasic taxonomic approach were used to determine the genomic profile and taxonomic status of the novel strain SYSU G05001T. Cell growth occurred at 37–80 °C (optimum, 55 °C), pH 6.0–8.0 (optimum, pH 7.0) and with 0–3.0 % (w/v) NaCl (optimum, 1%). Thiosulfate enhanced cell growth. MK-8 was the predominant menaquinone. The major cellular fatty acids included iso-C15 : 0, iso-C17 : 0 and anteiso-C15 : 0. The major polar lipids were consisted of aminophospholipid, glycolipid and phospholipids. The whole genome of strain SYSU G05001T consisted of 2.55 Mbp and the DNA G+C content was 64.94 mol%. The average nucleotide identity (≤94.95 %) and digital DNA–DNA hybridization (≤62.3 %) values between strain SYSU G05001T and other members of the genus Thermus were all lower than the threshold values recommended for distinguishing novel prokaryotic species. On the basis of the presented polyphasic evidence and genotypic data, it is proposed that strain SYSU G05001T (=KCTC 82627T=MCCC 1K06118T) represents a novel species of the genus Thermus , for which the name Thermus brevis sp. nov. is proposed.

A few members of the bacterial genus Thermus have been shown to be incomplete denitrifiers, terminating with nitrite (NO2−) or nitrous oxide (N2O). However, the denitrification abilities of the genus as a whole remain poorly characterized. Here, we describe diverse denitrification phenotypes and genotypes of a collection of 24 strains representing ten species, all isolated from a variety of geothermal systems in China. Confirmed terminal products of nitrate reduction were nitrite or N2O, while nitric oxide (NO) was inferred as the terminal product in some strains. Most strains produced N2O; complete denitrification was not observed. Denitrification phenotypes were largely consistent with the presence of denitrification genes, and strains of the same species often had the same denitrification phenotypes and largely syntenous denitrification gene clusters. Genes for nirS and nirK coexisted in three Thermus brockianus and three Thermus oshimai genomes, which is a unique hallmark of some denitrifying Thermus strains and may be ecologically important. These results show that incomplete denitrification phenotypes are prominent, but variable, within and between Thermus species. The incomplete denitrification phenotypes described here suggest Thermus species may play important roles in consortial denitrification in high-temperature terrestrial biotopes where sufficient supply of oxidized inorganic nitrogen exists.

Microbes are widespread in the sea that covers more than two-thirds of the earth's surface and most microorganisms living in the marine environment have yet to be cultured. Previous studies showed that drying treatment, a strategy of sample pre-treatment widely applied in microbial isolation and incubation, may alter the cultivable microbial diversity, such as Actinomycetota, essential for exploring novel secondary metabolites from the marine environment, isolated from drying-treated samples. However, whether drying treatments actually can change microbial community diversity and how the drying treatments of samples influence the cultivable microbial diversity of marine samples have not yet adequately been evaluated. Here, three marine sediment samples were dried and incubated at 28 ºC, 37 ºC, and 45 ºC, and the microbial diversity was assessed with high-throughput sequencing. Our results suggested that drying treatments had different effects on different genera and some potential novel species could be cultured only from drying-treated samples, including the novel members from the families Paenibacillaceae and Thermoactinomycetaceae. Non-metric multidimensional scaling analysis showed that the treated samples were clustered according to the cultivation temperatures rather than the drying conditions at high cultivation temperatures. However, at the cultivation temperatures of 28 ºC, drying treatments were the larger separation between cultivable microbial communities in the process of microbial isolation. These results showed that the drying treatments influenced the cultivated microbes in a taxon-specific pattern and extended potential novel taxa. Combining high-throughput sequencing to various drying conditions and incubation temperatures, this study provides new insight into the effects of drying treatment on the cultivable microbial diversity of marine sediments.

The group Nitriliruptoria, recently classified as a separate class of phylum Actinobacteria, has five members at present, which belong to halophilic or halotolerant Actinobacteria. Here, we sequenced the genomes of Egicoccus halophilus EGI 80432T and Egibacter rhizosphaerae EGI 80759T, and performed a comparative genomics approach to analyze the genomic differences and salt adaptation mechanisms in Nitriliruptoria. Phylogenetic analysis suggested that Euzebya tangerina F10T has a closer phylogenetic relationship to Euzebya rosea DSW09T, while genomic analysis revealed highest genomic similarity with Nitriliruptor alkaliphilus ANL-iso2T and E. halophilus EGI 80432T. Genomic differences of Nitriliruptoria were mainly observed in genome size, gene contents, and the amounts of gene in per functional categories. Furthermore, our analysis also revealed that Nitriliruptoria possess similar synthesis systems of solutes, such as trehalose, glutamine, glutamate, and proline. On the other hand, each member of Nitriliruptoria species possesses specific mechanisms, K+ influx and efflux, betaine and ectoine synthesis, and compatible solutes transport to survive in various high-salt environments.

Two Francisella -like bacteria, designated strains SYSU SYW-5T and SYSU SYW-6T, were isolated from coastal seawater sampled at Huizhou Double-Moon Bay, Guangdong Province, PR China. Cells were found to be Gram-stain-negative, non-motile, non-spore-forming and of pleomorphic shape (coccobacilli or rod). Chemotaxonomic analysis of the plasma membrane revealed ubiquinone-8 as the respiratory quinone, and saturated branched-chain (anteiso-C15 : 0) and saturated straight-chain (C18 : 0) fatty acids as major components (>8 % of total fatty acid). The major polar lipids comprised diphosphatidylglycerol (cardiolipin), phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine, as well as an unidentified aminophospholipid and an unidentified phospholipid in SYSU SYW-5T, and two unknown polar lipids in SYSU SYW-6T. Comparison of 16S rRNA gene sequences showed that SYSU SYW-5T had maximum similarity to Fastidiosibacter lacustris SYSU HZH-2T (93.4 %), while SYSU SYW-6Thad maximum similarity to Cysteiniphilum litorale SYSU D3-2T (97.5 %). Phylogenetic dendrograms based on 16S rRNA genes and 31 concatenated protein markers revealed that the two novel strains represent a distinct lineage within the family Fastidiosibacteraceae . The average nucleotide identity and in silico DNA–DNA hybridization values between the two isolates and their related species were well below the threshold limit for species delineation (

A novel actinobacterium, designated strain CFH 30434T, was isolated from a soil sample collected from a karst cave in Luoyang, Henan Province, PR China. The taxonomic position of the strain was investigated by using a polyphasic approach. Cells of the strain were aerobic, Gram-stain-positive, non-motile and coccoid or short rods. The strain was found to be oxidase-positive and weakly catalase-positive. Strain CFH 30434T grew optimally at 28 °C, pH 7.0–9.0 and in the presence of up to 0–1.5 % NaCl (w/v). The whole-cell sugars were glucose, mannose and rhamnose. The major isoprenoid quinone was MK-9(H8) and the major fatty acids (>10 % of the total fatty acids compositions) were anteiso-C15 : 0, iso-C15:0 and iso-C14 : 0. The polar lipids detected were diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unidentified phosphoglycolipid, an unidentified phospholipid and an unidentified glycolipid. The genomic DNA G+C content was determined to be 72.3 mol%. The results of phylogenetic analysis of 16S rRNA gene sequences indicated that CFH 30434T clustered within the family Promicromonosporaceae , and closely with the type strains of Xylanimicrobium pachnodae DSM 12657T, Myceligenerans crystallogenes DSM 17134T and Promicromonospora xylanilytica CCTCC AA 208046T (97.3 %, 96.2 and 95.9 % sequence similarities, respectively). Phylogenetic analysis showed that strain CFH 30434T formed a separate evolutionary branch, and was parallel to other related genera of Promicromonosporaceae . Its phylogenetic distinctiveness and distinguishing phenotypic characteristics supported that strain CFH 30434T represents a novel genus of the family Promicromonosporaceae , for which the name Antribacter gilvus gen. nov., sp. nov. is proposed. The type strain is CFH 30434T (=CGMCC 1.13856T=KCTC 49093T).

Trace metals have been an important ingredient for life throughout Earth’s history. Here, we describe the genome-guided cultivation of a member of the elusive archaeal lineage Caldarchaeales (syn. Aigarchaeota), Wolframiiraptor gerlachensis, and its growth dependence on tungsten. A metagenome-assembled genome (MAG) of W. gerlachensis encodes putative tungsten membrane transport systems, as well as pathways for anaerobic oxidation of sugars probably mediated by tungsten-dependent ferredoxin oxidoreductases that are expressed during growth. Catalyzed reporter deposition-fluorescence in-situ hybridization (CARD-FISH) and nanoscale secondary ion mass spectrometry (nanoSIMS) show that W. gerlachensis preferentially assimilates xylose. Phylogenetic analyses of 78 high-quality Wolframiiraptoraceae MAGs from terrestrial and marine hydrothermal systems suggest that tungsten-associated enzymes were present in the last common ancestor of extant Wolframiiraptoraceae. Our observations imply a crucial role for tungsten-dependent metabolism in the origin and evolution of this lineage, and hint at a relic metabolic dependence on this trace metal in early anaerobic thermophiles.

Phylogenomic analyses were performed on the nine species of the genus Meiothermus and four species of the genus Calidithermus. Phylogenetic analysis, low values of genomic relatedness indices and functional diversity analysis indicated that Meiothermus silvanus should not be classified within the clades for Meiothermus and Calidithermus but instead be reclassified as a new genus, for which we propose the name Allomeiothermus gen. nov., with Allomeiothermus silvanus comb. nov. as type species. In addition, the species Meiothermus cateniformans Zhang et al. (Int J Syst Evol Microbial 60:840-844, 2010) should also be reclassified as a later heterotypic synonym of Meiothermus taiwanensis Chen et al. (Int J Syst Evol Microbiol 52:1647-1654, 2002) emend. Raposo et al. (2019). This reclassification is based on the high genomic relatedness indices (98.8% ANI; 90.2% dDDH; 99% AAI) that are above the threshold values necessary for defining a new species, as well as on the observation of overlapping functions on Principal Coordinate Analysis plot generated from Clusters of Orthologous Genes.

Biological denitrification is a significant process in nitrogen biogeochemical cycle of terrestrial geothermal environments, and Thermus species have been shown to be crucial heterotrophic denitrifier in hydrothermal system. Five Gram-stain negative, aerobic and rod-shaped thermophilic bacterial strains were isolated from hot spring sediments in Tibet, China. Phylogenetic analysis based on 16S rRNA gene and whole genome sequences indicated that these isolates should be assigned to the genus Thermus and were most closely related to Thermus caldifontis YIM 73026

“Candidatus Bathyarchaeia” is a phylogenetically diverse and widely distributed lineage often in high abundance in anoxic submarine sediments; however, their evolution and ecological roles in terrestrial geothermal habitats are poorly understood. In the present study, 35 Ca. Bathyarchaeia metagenome-assembled genomes (MAGs) were recovered from hot spring sediments in Tibet and Yunnan, China. Phylogenetic analysis revealed all MAGs of Ca. Bathyarchaeia can be classified into 7 orders and 15 families. Among them, 4 families have been first discovered in the present study, significantly expanding the known diversity of Ca. Bathyarchaeia. Comparative genomics demonstrated Ca. Bathyarchaeia MAGs from thermal habitats to encode a large variety of genes related to carbohydrate degradation, which are likely a metabolic adaptation of these organisms to a lifestyle at high temperatures. At least two families are potential methanogens/alkanotrophs, indicating a potential for the catalysis of short-chain hydrocarbons. Three MAGs from Family-7.3 are identified as alkanotrophs due to the detection of an Mcr complex. Family-2 contains the largest number of genes relevant to alkyl-CoM transformation, indicating the potential for methylotrophic methanogenesis, although their evolutionary history suggests the ancestor of Ca. Bathyarchaeia was unable to metabolize alkanes. Subsequent lineages have acquired the ability via horizontal gene transfer. Overall, our study significantly expands our knowledge and understanding of the metabolic capabilities, habitat adaptations, and evolution of Ca. Bathyarchaeia in thermal environments. IMPORTANCECa. Bathyarchaeia MAGs from terrestrial hot spring habitats are poorly revealed, though they have been studied extensively in marine ecosystems. In this study, we uncovered the metabolic capabilities and ecological role of Ca. Bathyarchaeia in hot springs and give a comprehensive comparative analysis between thermal and nonthermal habitats to reveal the thermal adaptability of Ca. Bathyarchaeia. Also, we attempt to determine the evolutionary history of methane/alkane metabolism in Ca. Bathyarchaeia, since it appears to be the first archaea beyond Euryarchaeota which contains the mcrABG genes. The reclassification of Ca. Bathyarchaeia and significant genomic differences among different lineages largely expand our knowledge on these cosmopolitan archaea, which will be beneficial in guiding the future studies.

"Candidatus Aenigmarchaeota" ("Ca. Aenigmarchaeota") represents one of the earliest proposed evolutionary branches within the Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, and Nanohaloarchaeota (DPANN) superphylum. However, their ecological roles and potential host-symbiont interactions are still poorly understood. Here, eight metagenome-assembled genomes (MAGs) were reconstructed from hot spring ecosystems, and further in-depth comparative and evolutionary genomic analyses were conducted on these MAGs and other genomes downloaded from public databases. Although with limited metabolic capacities, we reported that "Ca. Aenigmarchaeota" in thermal environments harbor more genes related to carbohydrate metabolism than "Ca. Aenigmarchaeota" in nonthermal environments. Evolutionary analyses suggested that members from the Thaumarchaeota, Aigarchaeota, Crenarchaeota, and Korarchaeota (TACK) superphylum and Euryarchaeota contribute substantially to the niche expansion of "Ca. Aenigmarchaeota" via horizontal gene transfer (HGT), especially genes related to virus defense and stress responses. Based on co-occurrence network results and recent genetic exchanges among community members, we conjectured that "Ca. Aenigmarchaeota" may be symbionts associated with one MAG affiliated with the genus Pyrobaculum, though host specificity might be wide and variable across different "Ca. Aenigmarchaeota" organisms. This study provides significant insight into possible DPANN-host interactions and ecological roles of "Ca. Aenigmarchaeota." IMPORTANCE Recent advances in sequencing technology promoted the blowout discovery of super tiny microbes in the Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, and Nanohaloarchaeota (DPANN) superphylum. However, the unculturable properties of the majority of microbes impeded our investigation of their behavior and symbiotic lifestyle in the corresponding community. By integrating horizontal gene transfer (HGT) detection and co-occurrence network analysis on "Candidatus Aenigmarchaeota" ("Ca. Aenigmarchaeota"), we made one of the first attempts to infer their putative interaction partners and further decipher the potential functional and genetic interactions between the symbionts. We revealed that HGTs contributed by members from the Thaumarchaeota, Aigarchaeota, Crenarchaeota, and Korarchaeota (TACK) superphylum and Euryarchaeota conferred "Ca. Aenigmarchaeota" with the ability to survive under different environmental stresses, such as virus infection, high temperature, and oxidative stress. This study demonstrates that the interaction partners might be inferable by applying informatics analyses on metagenomic sequencing data.

Strain DRQ-2T (type strain of Nonomuraea indica) is worthy for genome sequencing, due to its ability to produce a wide variety of industrially important enzymes such as amylase, asparaginase, cellulase, gelatinase, glutaminase, and protease. Genome sequencing and comparison of strain DRQ-2T is described in the present work. The genome size was estimated to be 8,288,417 (bp) that consisted of 59 contigs. The G + C content of the genome was 72.4%. A total of 7730 genes were predicted with two rRNAs and 64 tRNAs. The genome analysis of the strain DRQ-2T showed the presence of a wide range of secondary metabolite gene clusters. Pan-Genomes Analysis Pipeline (PGAP) indicated that strain DRQ-2T had large numbers of unique genes. The majority of N. indica DRQ-2T genes encode for hypothetical proteins, indicating the functions of these ortholog clusters were still remain to be determined.

A novel actinobacterial strain, designated SYSU K12189

A novel endophytic bacterium, designated strain SZ4R5S7T, was isolated from surface-sterilized root of an endangered medicinal plant (Ferula songorica Pall. ex Spreng) collected from Xinjiang, north-west China. The taxonomic position of the strain was investigated by using a polyphasic approach. The strain was found to be aerobic, Gram-stain-positive, oxidase-negative and catalase-positive, short rods and non-motile. Strain SZ4R5S7T grew at 4–37 °C (optimum, 28 °C), pH 5.0–9.0 (pH 6.0–8.0) and in the presence of 0–4 % (w/v) NaCl. The polar lipids detected for strain SZ4R5S7T were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and two unidentified lipids. The predominant menaquinone of strain SZ4R5S7T was MK-8(H4), and the major fatty acids were iso-C16 : 0 and anteiso-C14 : 0. The DNA G+C content was determined to be 72.4 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain SZ4R5S7T belongs to the genus Nocardioides and showed highest levels of 16S rRNA gene sequence similarity to members of the strain Nocardioides kribbensis KSL-2T (97.8 %). On the basis of phenotypic, genotypic and phylogenetic data, strain SZ4R5S7T represents a novel species in the genus Nocardioides, for which the name Nocardioides ferulae sp. nov. is proposed and the type strain is SZ4R5S7T (=CGMCC 4.7456T=KCTC 39994T).

Strain SYSU D60016T, a rod-shaped bacterium that tends to form clusters, was isolated from a soil sample collected from the Gurbantunggut desert, China. Cells were Gram-stain-negative, catalase-negative and oxidase-positive. The 16S rRNA gene sequence of strain SYSU D60016T shared less than 94 % sequence identity with members of the family Hymenobacteraceae . The strain exhibited growth at 15–50 °C, pH 6–8 and in the presence of up to 3 % (w/v) NaCl. Its chemotaxonomic features included MK-7 as the respiratory menaquinone, iso-C15 : 0 and summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B) as major cellular fatty acids and phosphatidylethanolamine as the main polar lipid. The DNA G+C content was determined to be 50.1 % (genome). Analyses of the phylogenetic data and differences in the chemotaxonomic and biochemical features from related genera in the family Hymenobacteraceae indicated that strain SYSU D60016T merits representation of a novel species of a novel genus in the family Hymenobacteraceae . The name Botryobacter ruber gen. nov., sp. nov. is, therefore, proposed to represent the phylogenetic position of strain SYSU D60016T in the family Hymenobacteraceae . The type strain of the proposed new taxon is SYSU D60016T (=KCTC 52794T=NBRC 112957T).

A motile, rod-shaped and yellow coloured proteobacterium, designated strain SYSU D60017T, was isolated from a desert soil sample. The bacterium was found to be an obligately aerobic, mesophilic and neutrophilic chemo-heterotroph. Cells were observed to be Gram-stain negative, catalase positive and oxidase positive. The major cellular fatty acids were identified as C19:0ω8c cyclo and Summed Feature 8 (C18:1ω7c and/or C18:1ω6c). The main respiratory quinone identified was ubiquinone-10. The DNA G + C content was determined to be 63.8% based on draft genome sequence data. The polar lipids detected were identified as diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and five unidentified polar lipids. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SYSU D60017T is a member of the order Rhizobiales, but forms a distinct phylogenetic lineage. The differences in the phenotypic characteristics from members of related genera and its distinct phylogenetic position suggested that the isolate SYSU D60017T represents a novel species of a novel genus within the order Rhizobiales, for which the name Flaviflagellibacter deserti gen. nov., sp. nov. is proposed. The type strain of the new taxon is SYSU D60017T (= CGMCC 1.16444T = NBRC 112958T).

Two bacterial strains SYSU G02173

Microbes are the most abundant and diverse cellular life forms on Earth and colonize a wide range of environmental niches. However, more than 99% of bacterial and archaeal species have not been obtained in pure culture [1] and we have only glimpsed the surface of this mysterious microbial world. This is so-called Microbial Dark Matter (MDM): the enormous diversity of yet-uncultivated microbes that microbiologists can only study by using cultivation-independent techniques. Recently, a number of international projects have dramatically increased our understanding of the extent and distribution of microbial diversity, including the Global Catalogue of Microorganisms (GCM), the Genomic Encyclopedia of Bacteria and Archaea (GEBA), the Earth Microbiome Project (EMP), the Genomic Encyclopedia of Bacteria and Archaea-Microbial Dark Matter (GEBA-MDM) and several primate microbiome projects; however, the functional diversity of MDM is still mysterious. This perspective addresses why MDM deserves scientific effort and illustrates challenges and opportunities in the future study of these enigmas.

Background: ‘Ca. Aenigmarchaeota’ represents an evolutionary branch within the DPANN superphylum. However, their ecological roles and potential host-symbiont interactions are poorly understood.Results: Here, we analyze eight metagenomic-assembled genomes from hot spring habitats and reveal their functional potentials. Although they have limited metabolic capacities, they harbor substantial carbohydrate metabolizing abilities. Further investigation suggests that horizontal gene transfer might be the main driver that endows these abilities to ‘Ca. Aenigmarchaeota’, including enzymes involved in glycolysis. Additionally, members from the TACK superphylum and Euryarchaeota contribute substantially to the niche expansion of ‘Ca. Aenigmarchaeota’, especially genes related to carbohydrate metabolism and stress responses. Based on co-occurrence network analysis, we conjecture that ‘Ca. Aenigmarchaeota’ may be symbionts associated with TACK archaea and Euryarchaeota, though host-specificity might be wide and variable across different ‘Ca. Aenigmarchaeota’ genomes. Conclusion: This study provides significant insights into possible host-symbiont interactions and ecological roles of ‘Ca. Aenigmarchaeota’.

A non-motile, coccobacilli-shaped and yellow-coloured bacterium, designated strain SYSU D60003T, was isolated from a desert soil sample. Cells were Gram-stain-positive, catalase-negative and oxidase-positive. The whole cell hydrolysates contained ll-diaminopimelic acid as the diagnostic amino acid. The major fatty acids were C16 : 0, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and iso-C16 : 0. The respiratory menaquinones were MK-9(H8), MK-9(H4) and MK-9(H6). The DNA G+C content was determined to be 70.2 % (genome). The polar lipids detected were diphosphatidylglycerol, an unidentified glycolipid and seven unidentified polar lipids. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SYSU D60003T belonged to the order Acidimicrobiales (class Acidimicrobiia ), but formed a clade closely linked to members of the genus Ilumatobacter . Data from a polyphasic taxonomy study suggested that the isolate represents a novel species of a novel genus in the order Acidimicrobiales , for which the name Desertimonas flava gen. nov., sp. nov. is proposed. The type strain of the proposed new taxon is SYSU D60003T (=KCTC 39917T=NBRC 112924T). Additionally, the new taxon along with the genus Ilumatobater (family unassigned) were distinctly separated from the related families Acidimicrobiaceae , Iamiaceae and ‘Microtrichaceae’ in the phylogenetic trees, besides presenting a unique 16S rRNA gene signature nucleotides. Therefore, we propose a new family Ilumatobacteraceae fam. nov. within the order Acidimicrobiales to accommodate members of these two genera.

Two closely related, thermophilic bacteria, designated strains YIM 76954T and YIM 76947, were isolated from the Rehai Geothermal Field, Tengchong, Yunnan province, south-west China. Polyphasic approach and whole genome sequencing were used to determine the taxonomy status and genomic profiles of the novel strains. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two isolates were closely related to Thermus scotoductus SE-1T (97.1% sequence similarity), and T. amyloliquefaciens YIM 77409T (96.6%). The strains could be differentiated from most recognized Thermus species by their whitish to slight reddish colony color, distinct DNA fingerprinting profiles and low ANI values. Cells stained Gram-negative, rod-shaped of diameter 0.2-0.5μm and length 1.5-5.0μm. Growth occurred at 50-75°C, pH 6.0-9.0 and in the presence of up to 1.0% (w/v) NaCl concentration. Thiosulfate was found to enhance cell growth, besides improving the intensity of its colony color. Oxygen, nitrate, sulfur, and Fe(III) could be used as terminal electron acceptors for growth. MK-8 was the major respiratory menaquinone. Major fatty acids were iso-C17:0, iso-C15:0, anteiso-C17:0, and anteiso-C15:0. The genome size was 2.26Mbp with 65.5% average GC content. A total of 2374 genes was predicted, comprising 2322 protein-coding and 52 RNA genes. On the basis of the polyphasic evidence presented, it is proposed that strain YIM 76954T represents a novel species of the genus Thermus, for which the name Thermus tenuipuniceus sp. nov. is proposed. The type strain is YIM 76954T (=JCM 30350T=KCTC 4677T).

Genome analysis is one of the main criteria for description of new taxa. Availability of genome sequences for all the actinobacteria with a valid nomenclature will, however, require another decade's works of sequencing. This paper describes the rearrangement of the higher taxonomic ranks of the members of the phylum '

Rapid growth of genome data provides opportunities for updating microbial evolutionary relationships, but this is challenged by the discordant evolution of individual genes. Here we build a reference phylogeny of 10,575 evenly-sampled bacterial and archaeal genomes, based on a comprehensive set of 381 markers, using multiple strategies. Our trees indicate remarkably closer evolutionary proximity between Archaea and Bacteria than previous estimates that were limited to fewer “core” genes, such as the ribosomal proteins. The robustness of the results was tested with respect to several variables, including taxon and site sampling, amino acid substitution heterogeneity and saturation, non-vertical evolution, and the impact of exclusion of candidate phyla radiation (CPR) taxa. Our results provide an updated view of domain-level relationships., The authors build a reference phylogeny of 10,575 evenly-sampled bacterial and archaeal genomes, based on 381 markers. The results indicate a remarkably closer evolutionary proximity between Archaea and Bacteria than previous estimates that used fewer “core” genes, such as the ribosomal proteins.

A novel actinobacterium, designated strain CFH 30183T, was isolated from a soil sample collected from a karst cave in Luoyang, Henan Province. The taxonomic position of the strain was investigated using a polyphasic approach. Cells of strain CFH 30183T were observed to be Gram-stain positive, motile, asporogenous and coccoid to rod shaped. The strain was found to be aerobic and oxidase positive. On the basis of 16S rRNA gene sequence analysis, strain CFH 30183T was found to be closely related to Ornithinimicrobium murale 01-Gi-040T (97.8% sequence identity). The ANIb/ANIm values between strain CFH 30183T and O. murale DSM 22056T were found to be 80.3%/85.9%. Strain CFH 30183T was found to grow optimally at 28–32 °C, at pH 8.0–9.0 and in the presence of up to 7% NaCl (w/v). Whole cell hydrolysates of strain CFH 30183T contained l-ornithine as the diagnostic diamino acid, and arabinose, glucose, mannose and rhamnose as whole cell sugars. The respiratory quinone was determined to be MK-8(H4), while the major fatty acids were found to consist of iso-C15:0 and iso-C16:0. The polar lipids profile was found to include diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, an unidentified phospholipid, an unidentified phosphoglycolipid and four unidentified lipids. The DNA G + C content of strain CFH 30183T was calculated to be 70.9%. Based on the phenotypic, genotypic and phylogenetic data obtained, strain CFH 30183T is considered to represent a novel species of the genus Ornithinimicrobium, for which the name Ornithinimicrobium cavernae sp. nov. is proposed. The type strain is CFH 30183T (= KCTC 49018T = CGMCC 1.16393T).

A novel actinobacterium, designated strain CFH 30205T, was isolated from a soil sample collected from a karst cave in Luoyang, Henan Province, China. The taxonomic position of the strain was investigated by using a polyphasic approach. Cells of the strain were aerobic, Gram-stain-positive, non-motile and rod-shaped. The strain was found to be catalase- and oxidase-positive. Strain CFH 30205T grew optimally at 28 °C, pH 9.0 and in the presence of up to 1.5 % NaCl (w/v). On the basis of 16S rRNA gene sequence analysis, strain CFH 30205T was most closely related to the type strains of Nocardioides terrigena DS-17T (97.6 % sequence similarity) and Nocardioides sediminis MSL-01T (97.0 %). The DNA G+C content was determined to be 69.9 mol%. ll-2,6-Diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The whole-cell sugars were mannose, xylose and galactose. The major isoprenoid quinone was MK-8 (H4), and the major fatty acids (>10 %) were iso-C16 : 0 and anteiso-C14 : 0. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unidentified phospholipid. On the basis of phenotypic, genotypic and phylogenetic data, strain CFH 30205T merits representation of a novel species of the genus Nocardioides , for which the name Nocardioides allogilvus sp. nov. is proposed. The type strain is CFH 30205T (=KCTC 49020T=CGMCC 4.7457T).

A Gram-negative bacterium, designated as strain YIM 690229T, was isolated from the roots of Limonium otolepis. The strain was able to grow at 10–40 °C (optimum, 28–37 °C), pH 6.0–8.0 (optimum, 7.0) and in the presence of up to 7% NaCl (w/v) (optimum, up to 2.5%). Comparative 16S rRNA gene sequence analysis revealed that strain YIM 690229T shared less than 93.9% sequence similarities with members within the order Rhizobiales, and was remotely related to members of the family Hyphomicrobiaceae. Strain YIM 690229T was characterized by the presence of Q-10 as the predominant respiratory lipoquinone. The major fatty acids (> 10%) detected were C18:1 ω7c, C16:0, anteiso-C15:0 and summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B). The polar lipids consisted of diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmethylethanoamine and two unidentified lipids. The genomic DNA G + C content was 57.2 mol%. Data from this polyphasic taxonomy study suggested that strain YIM 690229T should be classified as a new species of a new genus within the family Hyphomicrobiaceae for which the name Limoniibacter endophyticus gen. nov., sp. nov., is proposed. The type species of the genus Limoniibacter gen. nov. is Limoniibacter endophyticus. The type strain of the species Limoniibacter endophyticus sp. nov. is YIM 690229T (= KCTC 42097T = JCM 30141T = CCTCC AB 2014130T = CGMCC 1.12906T).

A Francisella -like bacterium, designated strain SYSU HZH-2T, was isolated from a water sample collected from Haizhu Lake, Guangzhou, China. The bacterium was fastidious, and required an exogenous source of l-cysteine for its growth on artificial media. Cells were Gram-stain-negative, coccobacilli, non-motile and non-spore-forming. The strain shared highest 16S rRNA gene sequence similarities with Cysteiniphilum litorale SYSU D3-2T (94.6 % identity), Fangia hongkongensis UST040201-002T (93.2 %) and Caedibacter taeniospiralis 51T (91.6 %). This strain possessed ubiquinone-8 as the respiratory quinone; diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine and phosphatidylglycerol as the known polar lipids, and anteiso-C15 : 0 and C18 : 0 as the major fatty acids (>10 % of total fatty acids). The dendrograms based on 16S rRNA gene sequence analysis showed that it formed a separate cluster along with Cysteiniphilum litorale SYSU D3-2T, Caedibacter taeiniospiralis 51T and Fangia hongkongensis UST040201-002T. Based on the 16S rRNA gene sequence identity and differences in other phenotypic characteristics, the strain is considered to represent a novel species of a novel genus, for which the name Fastidiosibacter lacustris gen. nov., sp. nov. is proposed. The type strain of the type species Fastidiosibacter lacustris is SYSU HZH-2T (=NBRC 112274T = CGMCC 1.15950T). Additionally, the new taxon along with the genera Caedibacter , Cysteiniphilum and Fangia (family unassigned) were distinctly separated from the related families Francisellaceae , Piscirickettsiaceae and Thiotrichaeae in the phylogenetic trees. Therefore, we proposed a new family Fastidiosibacteraceae fam. nov. within the order Thiotrichales to accommodate these four genera.

A draft genome sequence of Jiangella alba YIM 61503T revealed a genome size of 7,664,864 bp arranged in 33 scaffolds. The genome was predicted to contain 7196 predicted genes, including 51 coding for RNA. Phylogenetic and comparative analyses of the draft genome of J. alba YIM 61503T with the available genomes of other Jiangella species suggested a proximal similarity between strains J. alba YIM 61503T and J. muralis DSM 45357T, while indicating a high divergence between J. gansuensis YIM 002T and other Jiangella species. The genome of J. alba YIM 61503T also revealed genes involved in indole-3-acetic acid biosynthesis and an alkylresorcinols gene cluster. Further, detection of phosphotransferase genes in the genome of all Jiangella species indicated that they can uptake and phosphorylate sugars. The presences of TreX-Z, TreS and OtsA-OtsB genes in some of the Jiangella strains also indicated a possible mechanism for their tolerance of high salinity. Besides providing new insights into its genetic features, our results suggested that J. alba YIM 61503T could be a potential strain for further genome mining studies. The release of this genome may, therefore, provide a better prospect for understanding "evolutionary taxonomy" about this genus in future.

A novel Gram-stain-positive, obligately anaerobic and thermophilic bacterium, strain SYSU GA15001T, was isolated from a sample collected from a hot spring located in Tengchong, China. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain SYSU GA15001T belonged to the family Eubacteriaceae , and was closely related to ‘ Irregularibacter muris ’ 2PG-426-CC4.2T (93.6 % similarity), Garciella nitratireducens DSM 15102T (93.2 %) and Alkalibacter saccharofermentans Z-78920T (89.7 %). Cells were rods and motile by means of a subpolar flagellum. Spores were formed in old cultures. Optimum growth was observed at 45 °C, at pH 7 and in the presence of 1.5 % (w/v) NaCl. The strain utilized d-arabinose, dulcitol, d-galactose, glucose, lactose, maltose, d-mannose, raffinose, l-rhamnose, d-sorbitol, xylitol, l-alanine, l-arginine, glycine, l-isoleucine, l-leucine, dl-methionine, NH4Cl, l-proline and l-threonine as sole carbon/nitrogen sources. Additionally, complex substrates including beef extract, peptone, starch and yeast extract can also be used as sole energy sources. The major fatty acid methyl esters were C14 : 0, anteiso-C15 : 0 and C18 : 0. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, an unidentified polar lipid, three unidentified phospholipids and an unidentified glycolipid. The DNA G+C content was determined to be 35.6 mol%. Strain SYSU GA15001T was physiologically and phylogenetically distinguishable from its closely related genera, and merits assignment as representing the type species of a new genus Rhabdanaerobium, with the name Rhabdanaerobium thermarum gen. nov., sp. nov. The type strain of the type species is SYSU GA15001T (=CGMCC 1.5219T=KCTC 15623T).

Several recent studies have shown the presence of genes for the key enzyme associated with archaeal methane/alkane metabolism, methyl-coenzyme M reductase (Mcr), in metagenome-assembled genomes (MAGs) divergent to existing archaeal lineages. Here, we study the mcr-containing archaeal MAGs from several hot springs, which reveal further expansion in the diversity of archaeal organisms performing methane/alkane metabolism. Significantly, an MAG basal to organisms from the phylum Thaumarchaeota that contains mcr genes, but not those for ammonia oxidation or aerobic metabolism, is identified. Together, our phylogenetic analyses and ancestral state reconstructions suggest a mostly vertical evolution of mcrABG genes among methanogens and methanotrophs, along with frequent horizontal gene transfer of mcr genes between alkanotrophs. Analysis of all mcr-containing archaeal MAGs/genomes suggests a hydrothermal origin for these microorganisms based on optimal growth temperature predictions. These results also suggest methane/alkane oxidation or methanogenesis at high temperature likely existed in a common archaeal ancestor., Methane metabolism by some lineages of Archaea contributes to the cycling of carbon on Earth. Here, the authors show high diversity of methyl-coenzyme M reductase (Mcr), a key enzyme associated with archaeal methane/alkane metabolism, in hot spring Archaea, and investigate their ecological roles and evolution.

One thermophilic bacterium, designated strain SYSU G02662T, was isolated from hot spring sediment sampled in Tibet, PR China. Polyphasic taxonomic analyses and whole-genome sequencing were used to determine the taxonomy position of the strain. Phylogenetic analysis using 16S rRNA gene sequences indicated that strain SYSU G02662T showed the highest sequence similarity to Actinomarinicola tropica SCSIO 58843T (95.1 %). The strain could be differentiated from other species of the family Iamiaceae by its distinct phenotypic and genotypic characteristics. Cells of strain SYSU G02662T were aerobic, Gram-staining-positive and short rodshaped. Growth occurred optimally at 45 °C and pH 7.0. In addition, meso-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The respiratory quinone was MK-9 (H8), while the major fatty acids (>10 %) were C16 : 0, C17 : 0, C18 : 0 and iso-C16 : 0. The detected polar lipids included diphosphatidylglycerol, phosphatidylinositol mannoside and phosphatidylinositol. The G+C content of the genomic DNA was 70.5 % based on the draft genomic sequence. On the basis of phenotypic, genotypic and phylogenetic data, strain SYSU G02662T represents a novel species of a novel genus in the family Iamiaceae , for which the name Rhabdothermincola sediminis gen. nov., sp. nov. is proposed. The type strain of the proposed novel species is SYSU G02662T (=CGMCC 4.7688T=KCTC 49500T).

A Gram-stain-negative, aerobic, non-motile and rod-shaped bacterium, designated strain X7XT, was isolated from a rhizosphere soil sample of Nicotiana tabacum L. collected from a tobacco factory located in Kunming, south-western China. The cells showed oxidase-positive and catalase-positive reactions. Growth occurred at 20–40 °C and pH 6.0–8.0, with optimal growth at 30 °C and pH 7.0. The predominant respiratory quinone was MK-7. The major fatty acids were identified as iso-C15 : 0, iso-C17 : 0 3OH and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c). The cellular polar lipids contained phosphatidylethanolamine, an unidentified aminophospholipid, two unidentified glycolipids, four unidentified aminolipids and four unidentified lipids. The genomic DNA G+C content was 49.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain X7XT should be affiliated to the genus Flavisolibacter . Results from further analysis showed that strain X7XT had highest 16S rRNA gene sequence similarity to Flavisolibacter metallilatus TX0661T (96.4 %) and ‘ Flavisolibacter swuensis ’ SR2-4-2T (96.4 %), followed by other species of the genus Flavisolibacter . The polyphasic taxonomic characteristics indicated that strain X7XT represents a novel species of the genus Flavisolibacter , for which the name Flavisolibacter nicotianae sp. nov. (type strain X7XT=KCTC 62326T=CGMCC 16451T) is proposed.

In our search for novel anaerobes with potential carbohydrate polymers degrading activity, we have isolated a xylan-degrading bacterial strain SYSU GA17129T from an anammox bacteria dominant wastewater treatment plant. Phylogenetic analysis of the 16S rRNA gene sequence indicated the strain SYSU GA17129T belong to the order Clostridiales and shared highest sequence identity with Caldicoprobacter faecalis DSM 20678T (89.9%). The strain was thermophilic, obligately anaerobic, non-motile and rod shaped. Optimum growth of the strain was observed at 45 °C, pH 8.0 and in the presence of 0.5% NaCl (w/v). The chemotaxonomic features of the strain SYSU GA17129T comprised of C14:0 FAME, iso-C15:0 FAME and C16:0 FAME as the major fatty acids (>10%), diphosphatidylglycerol, phosphatidylinositol mannoside, an unidentified phospholipid, three unidentified polar lipids and two unidentified glycolipids as its polar lipids, and meso-diaminopimelic acid (meso-DAP) as the diamino acid in peptidoglycan. The G + C content of the genomic DNA was 35.9%. The strain could be distinguished from other defined families within the order Clostridiales by the differences in phenotypic and physiological characteristics, distinct phylogenetic lineage in 16S rRNA gene- and genome-based phylogenies and low genomic relatedness index. Based on these distinguishing properties, strain SYSU GA17129T is proposed to represent a new species of a new genus Xylanivirga thermophila gen. nov., sp. nov., within a new family Xylanivirgaceae fam. nov. The type species of the new taxon is SYSU GA17129T (=KCTC 15754T = CGMCC 1.5282T). This strain is characterized within the order Clostridiales, class Clostridia of the phylum Firmicutes.

Lignocellulose is considered a major source of renewable energy that serve as an alternative to the fossil fuels. Members of the genus Clostridium are some of the many microorganisms that have the ability to degrade lignocellulose efficiently to sugar, which can be further converted to biofuel. In this study, we isolated twelve Clostridium strains from hot spring samples of Yunnan and Tibet, of which isolates SYSU GA15002T and SYSU GA17076 showed low 16S rRNA gene sequence identity profiles to any of the validly named Clostridium strains (

A novel actinobacterium, designated strain SYSU K10002T, was isolated from a soil sample collected from a karst cave in Xingyi county, Guizhou province, south-western China. The taxonomic position of the strain was investigated using a polyphasic approach. Cells of the strain were aerobic and Gram-stain-positive. On the basis of 16S rRNA gene sequence similarities and phylogenetic analysis, strain SYSU K10002T was most closely related to the type strains of Nocardiaaltamirensis NBRC 108246T (99.0 % sequence similarity) and Nocardiatenerifensis NBRC 101015T (98.8 %) and is therefore considered to represent a member of the genus Nocardia . DNA–DNA hybridization values between strain SYSU K10002T and the closely related type strains of the genus Nocardia were less than 70 %. In addition, meso-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The whole-cell sugars were arabinose, ribose and galactose. The major isoprenoid quinone was MK-8(H4,ω-cycl), while the major fatty acids (>10 %) were C16 : 0, C18 : 1ω9c and C18 : 0 10-methyl. The polar lipids contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified glycolipid. Mycolic acids were present. The genomic DNA G+C content of strain SYSU K10002T was 67.4 mol%. On the basis of phenotypic, genotypic and phylogenetic data, strain SYSU K10002T represents a novel species of the genus Nocardia , for which the name Nocardia aurea sp. nov. is proposed. The type strain is SYSU K10002T (=KCTC 39849T=DSM 103986T).

A Gram-stain negative, facultatively anaerobic, rod-shaped, non-motile and non-spore forming bacterium, designated ZS-11T, was isolated from an artificial freshwater lake in Guangzhou city, Guangdong province, China. Growth of strain ZS-11T was observed at the temperature 18–42 °C (optimum 32–37 °C), pH 6.0–8.0 (optimum 7.0) and 0.5–3.0% (w/v) NaCl (optimum 0.5%, w/v), and also found to be enhanced in the presence of CO2. Pairwise comparison of 16S rRNA gene sequences showed that the strain shared high similarities with Serratia entomophila DSM 12358T (96.1%), Serratia ficaria DSM 4569T (96.0%), Serratia plymuthica DSM 4540T (96.0%), Rahnella victoriana FRB 225T (95.9%) and Rouxiella badensis DSM 100043T (95.8%). The phylogenomic dendrograms showed that strain ZS-11T formed a distinct cluster within the clade of the genus Serratia. The major fatty acids (> 20%) present in the cells were C16:0, C16:1ω7c/C16:1ω6c and C18:1ω7c/C18:1ω6c, which were consistent with those of S. entomophila CCUG 55496T and Serratia liquefaciens CCUG 9285T. The DNA G + C content for the genome was 49.3%. Based on these phenotypic and genotypic data, strain ZS-11T is considered to represent a new species of the genus Serratia, for which the name Serratia microhaemolytica sp. nov. is proposed. The type strain is ZS-11T (= CCTCC AB 2018040T = KCTC 62413T).

A novel actinobacterial strain, designated SYSU K12189T, was isolated from a soil sample collected from a Karst cave in Xingyi county, Guizhou province, south-western China. The taxonomic position of the strain was investigated using a polyphasic approach. Cells of the strain were observed to be aerobic and Gram-stain positive. On the basis of 16S rRNA gene sequence similarities and phylogenetic analysis, strain SYSU K12189T is closely related to the type strains of the genus Microlunatus, Microlunatus parietis 12-Be-011T (98.5% sequence similarity), Microlunatus nigridraconis CPCC 203993T (98.4%) and Microlunatus cavernae YIM C01117T (96.6%), and is therefore considered to represent a member of the genus Microlunatus. DNA–DNA hybridization values between strain SYSU K12189T and related type strains of the genus Microlunatus were 10%) were found to be anteiso-C15:0, iso-C15:0, iso-C16:0 and iso-C14:0. The polar lipids were found to contain diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, three glycolipids and two unidentified lipids. The genomic DNA G+C content of strain SYSU K12189T was determined to be 69.4 mol%. On the basis of phenotypic, genotypic and phylogenetic data, strain SYSU K12189T is concluded to represent a novel species of the genus Microlunatus, for which the name Microlunatus speluncae sp. nov. is proposed. The type strain is SYSU K12189T (= KCTC 39847T = DSM 103947T).

This paper presents a special piezoelectric energy harvester system which is obtained by separating the end of the upper piezoelectric layer of the traditional piezoelectric cantilever beam from its basic layer. A mass I is located at the end of the separated upper piezoelectric layer (SUPL), a mass II and a permanent magnet I are located at the end of the separated lower piezoelectric beam (SLPB) and a permanent magnet II is added in the opposite position of the permanent magnet I and they face each other with same polarities. A nonlinear magnetic force which can broaden the frequency bandwidth of the system is generated mutually on the two permanent magnets. Studies find that this special piezoelectric energy harvester has extremely high energy capture efficiency. In order to further explore the reason of high efficiency, experimental research on its dynamic behavior is carried out. The experimental results show that the vibrations of the SUPL and the SLPB are relatively simple. The dynamic behaviors of the SUPL, the SLPB and the unseparated part are different. The unseparated part of the piezoelectric shows relatively complex nonlinear phenomenon due to the interaction of nonlinear magnetic force and the collision. With the increase of the external excitation frequency, period doubling motion and almost periodic motion appear alternately.

A Gram-negative, aerobic, non-motile and non-spore forming bacterium, designated strain SYSU WZ-2T, was isolated from an estuarine seawater sample. Growth of strain SYSU WZ-2T was observed at temperature range of 10–40° C (optimum, 32 °C), pH range of 6–10 (optimum, pH 7–8) and in the presence of up to 5.0% NaCl (w/v). The DNA G+C content of the novel strain was determined to be 30.1% (genome). The major polar lipids were found to be diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, an unidentified aminolipid, two unidentified aminophospholipids and two unidentified phospholipids. The major fatty acids were C18:0 3-OH (27.5%), C18:1ω9c (19.3%), C16:0 (17.0%) and C14:0 (12.9%). The respiratory quinone was found to be ubiquinone Q8. Pairwise comparison of the 16S rRNA gene sequence showed that strain SYSU WZ-2T shares high identities with members of the genera Francisella (94.8–95.9%) and Allofrancisella (93.8–94.2%). The phylogenetic dendrograms based on 16S rRNA gene sequences with the members of the family Francisellaceae showed that the strain SYSU WZ-2T formed a distinct phylogenetic lineage well separated from the members of the genera Francisella and Allofrancisella. MALDI-TOF mass spectrometric analysis also depicted a different profile for strain SYSU WZ-2T compared with those of members of the genera Francisella and Allofrancisella. Based on the above results and differences in phenotypic and chemotaxonomic features, strain SYSU WZ-2T is characterized to represent a new species of a novel genus, for which the name Pseudofrancisella aestuarii gen. nov., sp. nov. is proposed (type strain SYSU WZ-2T = KCTC 52557T = CGMCC 1.13718T).

Hot springs indicate where hot water is emitted from the Earth; they are situated in many parts of the world, and most of them are known for their medical importance. Extensive research has been conducted to understand their chemical composition and microbial diversity. This chapter focuses on some important Indian hot springs, their locations, components, and importance. Much emphasis is placed on understanding their microbial diversity, including culture dependent, as well as independent methods. This chapter also sheds light on various Indian hot spring’s uniqueness, novel strains that have been reported, and information regarding the genome sequence for strains that have been isolated from Indian hot springs. The bioactive molecules, such as enzymes and antibiotics obtained from hot springs, are also listed here.

Bacterioplankton are the major driving force for biogeochemical cycles in estuarine ecosystems, but the communities that mediate these processes are largely unexplored. We sampled in the Pearl River Estuary (PRE) to examine potential differences in the taxonomic composition of resident (DNA-based) and active (RNA-based) bacterioplankton communities in free-living and particle-associated fractions. MiSeq sequencing data showed that the overall bacterial diversity in particle-associated fractions was higher than in free-living communities. Further in-depth analyses of the sequences revealed a positive correlation between resident and active bacterioplankton communities for the particle-associated fraction but not in the free-living fraction. However, a large overlapping of OTUs between free-living and particle-associated communities in PRE suggested that the two fractions may be actively exchanged. We also observed that the positive correlation between resident and active communities is more prominent among the abundant OTUs (relative abundance > 0.2%). Further, the results from the present study indicated that low-abundance bacterioplankton make an important contribution towards the metabolic activity in PRE.

A novel Gram-stain-negative, non-motile, rod-shaped and watermelon-red-pigmented aerobic bacterial strain, designated YIM 77969T, was isolated from a soil sample of Jiuxiang cave, a tourism cave located in Yiliang county, Yunnan province, south-west China. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain YIM 77969T belongs to the genus Hymenobacter, and was closely related to Hymenobacter tibetensis XTM003T (96.58 %), Hymenobacter gelipurpurascens Txg1T (96.02 %) and Hymenobacter xinjiangensis X2-1gT (95.80 %). Growth of strain YIM 77969T occurred at 5–35 °C, at pH 5.0–9.0 and in the presence of 0–1 % (w/v) NaCl. The predominant menaquinone was MK-7. The major fatty acids were iso-C15 : 0, C16 : 1ω5c and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The polar lipid profiles consisted of the major compound phosphatidylethanolamine, two unknown aminolipids, three unknown aminophospholipids, one glycolipid and one unknown polar lipid. Pigment analysis showed that the pigment belonged to the plectaniaxanthin series of carotenoid pigments. The genomic DNA G+C content was 55.2 mol%. On the basis of phylogenetic, phenotypic and chemotaxonomic characteristics, strain YIM 77969T is considered to represent a novel species of the genus Hymenobacter, for which the name Hymenobacter mucosus sp. nov. is proposed. The type strain is YIM 77969T ( = KCTC 32567T = DSM 28041T).

A draft genome sequence of Jiangella alba YIM 61503