Actinocatenispora thailandica gen. nov., sp. nov., a new member of the family Micromonosporaceae

Actinocatenispora comari sp. nov., an endophytic actinomycete isolated from aerial parts of Comarum salesowianum

A novel actinomycete, designated NUM-2625^T, was isolated as an endophytic bacterium in aerial parts of Comarum salesowianum, an endemic species in the Altai, Himalaya mountain chain area, collected from Khasagt Khairkhan Mountain in Mongolia. The 16S rRNA gene sequence of strain NUM-2625^T showed the highest similarity to Actinocatenispora thailandica TT2-10^T (99.4 %), Actinocatenispora sera KV-744^T (99.3 %), and Actinocatenispora rupis CS5-AC17^T (97.7 %). Chemotaxonomic properties of strain NUM-2625^T were essentially consistent with those of the genus Actinocatenispora, such as the presence of meso-diaminopimelic acid as the diagnostic diamino acid of the peptidoglycan, MK-9(H₄) and MK-9(H₆) as the major menaquinones, and iso-C_16 : 0, iso-C_15 : 0, iso-C_14 : 0 3-OH, and anteiso-C_17 : 0 as the major fatty acids. Meanwhile, digital DNA-DNA hybridization and average nucleotide identity values revealed a low relatedness between strain NUM-2625^T and the other type strains of the genus Actinocatenispora. In addition, strain NUM-2625^T exhibited several phenotypic properties that could be used to distinguish it from its closest relatives. Based on the results of polyphasic analyses, strain NUM-2625^T represents a novel species in the genus Actinocatenispora, for which the name Actinocatenispora comari sp. nov. is proposed. The type strain is NUM-2625^T (=NBRC 114660^T=TBRC 13496^T).

Diversity of the bacterial community in the rice rhizosphere managed under conventional and no-tillage practices

Bacterial diversity in the rice rhizosphere at different rice growth stages, managed under conventional and no-tillage practices, was explored using a culture-based approach. Actinobacteria are among the bacterial phyla abundant in the rice rhizosphere. Their diversity was further examined by constructing metagenomic libraries based on the 16S rRNA gene, using actinobacterial- and streptomycete-specific polymerase chain reaction (PCR) primers. The study included 132 culturable strains and 125 clones from the 16S rRNA gene libraries. In conventional tillage, there were 38% Proteobacteria, 22% Actinobacteria, 33% Firmicutes, 5% Bacteroidetes, and 2% Acidobacteria, whereas with no-tillage management there were 63% Proteobacteria, 24% Actinobacteria, 6% Firmicutes, and 8% Bacteroidetes as estimated using the culture-dependent method during the four stages of rice cultivation. Principal coordinates analysis was used to cluster the bacterial communities along axes of maximal variance. The different growth stages of rice appeared to influence the rhizosphere bacterial profile for both cultivation practices. Novel clones with low similarities (89-97%) to Actinobacteria and Streptomyces were retrieved from both rice fields by screening the 16S rRNA gene libraries using actinobacterial- and streptomycete-specific primers. By comparing the actinobacterial community retrieved by culture-dependent and molecular methods, it was clear that a more comprehensive assessment of microbial diversity in the rice rhizosphere can be obtained using a combination of both techniques than by using either method alone. We also succeeded in culturing a number of bacteria that were previously described as unculturable. These were in a phylogenetically deep lineage when compared with related cultivable genera.

Wangella harbinensis gen. nov., sp. nov., a new member of the family Micromonosporaceae

A novel endophytic actinomycete, designated strain NEAU-J3(T), was isolated from soybean root (Glycine max (L.) Merr) and characterized using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences suggested that strain NEAU-J3(T) fell within the family Micromonosporaceae. The strain was observed to form an extensively branched substrate mycelium, which carried non-motile oval spores with a smooth surface. The cell walls of strain NEAU-J3(T) were determined to contain meso-diaminopimelic acid and galactose, ribose and glucose were detected as whole-cell sugars. The major menaquinones were determined to be MK-9(H(4)) and MK-9(H(6)). The phospholipids detected were phosphatidylcholine and phosphatidylethanolamine. The major cellular fatty acids were determined to be C(16:0), C(18:1) ω9c, C(18:0), C(17:0), C(17:1) ω7c, anteiso-C(17:0), C(16:1) ω7c and C(15:0). The DNA G + C content was 62.5 mol%. On the basis of the morphological and chemotaxonomic characteristics, phylogenetic analysis and characteristic patterns of 16S rRNA gene signature nucleotides, strain NEAU-J3(T) is considered to represent a novel species of a new genus within the family Micromonosporaceae, for which the name Wangella harbinensis gen. nov., sp. nov. is proposed. The type strain of Wangella harbinensis is strain NEAU-J3(T) (=CGMCC 4.7039(T) = DSM 45747(T)).

Xiangella phaseoli gen. nov., sp. nov., a member of the family Micromonosporaceae

A novel endophytic actinomycete, designated strain NEAU-J5(T) was isolated from roots of snap bean (Phaseolus vulgaris L.). Comparative analysis of the 16S rRNA gene sequence indicated that NEAU-J5(T) is phylogenetically related to members of the family Micromonosporaceae. The whole-cell sugars were galactose, mannose and glucose. The predominant menaquinones were MK-9(H4) and MK-9(H6). The major fatty acids were C16:0, C18:0, C17:1ω7c, iso-C15:0 and C17:0. The phospholipids were phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol and phosphatidylinositol mannoside. The DNA G+C content was 72.2 mol%. On the basis of the morphological and chemotaxonomic characteristics, phylogenetic analysis and characteristic patterns of 16S rRNA gene signature nucleotides, strain NEAU-J5(T) represents a novel species of a new genus within the family Micromonosporaceae, for which the name Xiangella phaseoli gen. nov., sp. nov. is proposed. The type strain of Xiangella phaseoli is strain NEAU-J5(T) (=CGMCC 4.7038(T)=DSM 45730(T)).

Phytomonospora endophytica gen. nov., sp. nov., isolated from the roots of Artemisia annua L

A novel endophytic actinomycete, strain YIM 65646T, was isolated from the roots of Artemisia annua L. collected from Yunnan Province, south-west China. Growth was observed in the temperature range 10–40 °C (optimum 20–28 °C) and at pH 6.0–9.0 (optimum pH 7.0). The organism formed well-developed, branched substrate mycelia, but aerial mycelium was not produced. Phenotypic characterization and 16S rRNA gene sequence analysis indicated that strain YIM 65646T belonged to the family Micromonosporaceae (sharing ≤93.6 % sequence similarity with members of this family) and formed a distinct clade in the Micromonosporaceae phylogenetic tree. The strain contained meso-diaminopimelic acid in the cell wall and mannose, ribose, galactose and glucose in whole-cell hydrolysates. The major menaquinones were MK-10(H4), MK-10(H2), MK-8(H2), MK-9(H2) and MK-10(H6). The major fatty acids were iso-C15 : 0, anteiso-C15 : 0, anteiso-C17 : 0, iso-C17 : 0 and iso-C16 : 0. The DNA G+C content of strain YIM 65646T was 70.0 mol%. On the basis of morphological and chemotaxonomic properties and phylogenetic analysis based on 16S rRNA gene sequence data, it is proposed that this strain should be classified in a novel genus and species, Phytomonospora endophytica gen. nov., sp. nov., in the family Micromonosporaceae. The type strain is YIM 65646T ( = CCTCC AA 209041T  = DSM 45386T).

Allocatelliglobosispora scoriae gen. nov., sp. nov., isolated from volcanic ash

A novel actinomycete, designated strain Sco-B14T, was isolated from volcanic ash collected near Darangshi Oreum (a parasitic or satellite volcano) in Jeju, Republic of Korea. The organism formed well-developed, branched substrate mycelium, on which short chains of non-motile spores were arranged singly or in clusters. Aerial mycelium was not produced. Globose bodies were observed. The reverse colour of colonies was light brown to brown. Diffusible pigments were produced on ISP medium 3 and oatmeal-nitrate agar. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain Sco-B14T formed a lineage within the family Micromonosporaceae and was distinct from established genera. The 16S rRNA gene sequence similarity of strain Sco-B14T to members of related genera of the family was 95.0–95.7 % to type strains of Catellatospora species, 94.7 % to Hamadaea tsunoensis IMSNU 22005T, 94.7 % to Longispora albida K97-0003T and 94.0 % to Catelliglobosispora koreensis LM 042T. 3-Hydroxydiaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. Whole-cell sugars were glucose, rhamnose, ribose, xylose, arabinose, galactose and mannose. The polar lipids included diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol. The menaquinone profile contained MK-10(H4) (49 %), MK-9(H4) (24 %), MK-10(H6) (18 %) and MK-9(H6) (9 %). The predominant fatty acids were iso-C15 : 0 and C17 : 0. The DNA G+C content was 70.1 mol%. The combination of chemotaxonomic and phylogenetic data clearly separated the isolate from the type strains of all genera in the family Micromonosporaceae. On the basis of the phylogenetic and chemotaxonomic data presented in this paper, strain Sco-B14T is considered to represent a novel species of a new genus in the family Micromonosporaceae, for which the name Allocatelliglobosispora scoriae gen. nov., sp. nov. is proposed. The type strain of Allocatelliglobosispora scoriae is Sco-B14T (=KCTC 19661T =DSM 45362T).

Phytohabitans suffuscus gen. nov., sp. nov., an actinomycete of the family Micromonosporaceae isolated from plant roots

An actinomycete strain, K07-0523T, was isolated from the roots of an orchid collected in Okinawa prefecture, Japan. 16S rRNA gene sequence analysis indicated that the new strain belonged to the family Micromonosporaceae and the similarity values between strain K07-0523T and the type species of 24 genera in the family Micromonosporaceae were 93.3–97.7 %. Strain K07-0523T contained d-glutamic acid, glycine, d-alanine, meso-diaminopimelic acid, hydroxydiaminopimelic acid and l-lysine in the cell wall. The major menaquinones were MK-9(H6), MK-10(H4) and MK-10(H6). Galactose, glucose, mannose, ribose and xylose were present in the whole-cell sugars. The acyl type of the peptidoglycan was glycolyl. Major fatty acids were anteiso-C17 : 0, iso-C17 : 0, iso-C16 : 0 and iso-C15 : 0. Phosphatidylethanolamine was detected as the major phospholipid and corresponded to phospholipid type II. The G+C content of the genomic DNA was 73 mol%. On the basis of phylogenetic and chemotaxonomic data, the new strain represents a member of a new genus and novel species, namely Phytohabitans suffuscus gen. nov., sp. nov., in the family Micromonosporaceae. The type strain of the type species is K07-0523T (=DSM 45306T=NBRC 105367T).

Jishengella endophytica gen. nov., sp. nov., a new member of the family Micromonosporaceae

A novel endophytic actinomycete, designated strain 202201(T), was isolated from an Acanthus illicifolius root collected from the mangrove reserve zone in Hainan Province, China. Phylogenetic analysis based on 16S rRNA gene sequences suggested that strain 202201(T) fell within the family Micromonosporaceae. The strain formed an extensively branched substrate mycelium, which carried uneven warty-surfaced spores. Cell walls of strain 202201(T) contained meso-diaminopimelic acid and xylose, mannose, arabinose, ribose and glucose were detected as whole-cell sugars. The acyl type of the cell-wall polysaccharides was glycolyl. The major menaquinones were MK-9(H(4)), MK-9(H(6)), MK-9(H(8)) and MK-10(H(4)). The polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol mannoside and phosphatidylserine. The major cellular fatty acids were 10-methyl-C(17 : 0), iso-C(15 : 0), iso-C(16 : 0) and C(17 : 1)ω8c. The DNA G+C content was 72.3 mol%. On the basis of the morphological and chemotaxonomic characteristics, phylogenetic analysis and characteristic patterns of 16S rRNA gene signature nucleotides, strain 202201(T) ( = CGMCC 4.5597(T ) = DSM 45430(T)) represents a novel species of a new genus within the family Micromonosporaceae, for which the name Jishengella endophytica gen. nov., sp. nov. is proposed.

Actinaurispora siamensis gen. nov., sp. nov., a new member of the family Micromonosporaceae

Two actinomycete strains, CM2-8(T) and CM2-12, were isolated from temperate peat swamp forest soil in Chiang Mai Province, Thailand. Their taxonomic positions were determined using a polyphasic approach. Chemotaxonomic characteristics of these strains coincided with those of the family Micromonosporaceae, i.e. cell wall chemotype II, N-glycolyl type of muramic acid, and type II phospholipids. Phylogenetic analysis based on 16S rRNA gene sequence data also indicated that these strains fell within the family Micromonosporaceae and formed a distinct taxon in the Micromonosporaceae phylogenetic tree. On the basis of phylogenetic analysis, characteristic patterns of 16S rRNA gene signature nucleotides and chemotaxonomic data, it is proposed that the novel isolates belong to a new genus, Actinaurispora gen. nov. The type species of the genus is proposed as Actinaurispora siamensis sp. nov., with strain CM2-8(T) (=JCM 15677(T)=BCC 34762(T)) as the type strain.

Plantactinospora mayteni gen. nov., sp. nov., a member of the family Micromonosporaceae

A novel Gram-positive, aerobic, spore-forming, endophytic actinomycete, designated strain YIM 61359(T), was isolated from the roots of Maytenus austroyunnanensis plants collected from tropical rainforest in Xishuangbanna, Yunnan Province, south-west China. The strain formed single or cluster spores with smooth surfaces from substrate mycelia. The strain contained meso-diaminopimelic acid in the cell wall and arabinose, xylose, galactose and glucose in whole-cell hydrolysates. The acyl type of the cell-wall polysaccharides was glycolyl. MK-10(H(6)), MK-10(H(8)) and MK-10(H(4)) were the predominant menaquinones. The polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol and several unknown phospholipids. The major fatty acids were iso-C(15 : 0), anteiso-C(15 : 0), C(17 : 0), anteiso-C(17 : 0) and iso-C(16 : 0). The DNA G+C content of strain YIM 61359(T) was 69.7 mol%. These chemotaxonomic data indicated that the strain belongs to the family Micromonosporaceae. Phylogenetic analysis based on 16S rRNA gene sequences also suggested that strain YIM 61359(T) fell within the family Micromonosporaceae. On the basis of morphological and chemotaxonomic data, phylogenetic analysis and characteristic patterns of 16S rRNA gene signature nucleotides, strain YIM 61359(T) is considered to represent a novel species of a new genus within the family Micromonosporaceae, for which the name Plantactinospora mayteni gen. nov., sp. nov. is proposed. The type strain of Plantactinospora mayteni is YIM 61359(T) (=CCTCC AA 208022(T)=DSM 45238(T)).

An update of the structure and 16S rRNA gene sequence-based definition of higher ranks of the class Actinobacteria, with the proposal of two new suborders and four new families and emended descriptions of the existing higher taxa

The higher ranks of the class Actinobacteria were proposed and described in 1997. At each rank, the taxa were delineated from each other solely on the basis of 16S rRNA gene sequence phylogenetic clustering and taxon-specific 16S rRNA signature nucleotides. In the past 10 years, many novel members have been assigned to this class while, at the same time, some members have been reclassified. The new 16S rRNA gene sequence information and the changes in phylogenetic positions of some taxa influence decisions about which 16S rRNA nucleotides to define as taxon-specific. As a consequence, the phylogenetic relationships of Actinobacteria at higher levels may need to be reconstructed. Here, we present new 16S rRNA signature nucleotide patterns of taxa above the family level and indicate the affiliation of genera to families. These sets replace the signatures published in 1997. In addition, Actinopolysporineae subord. nov. and Actinopolysporaceae fam. nov. are proposed to accommodate the genus Actinopolyspora, Kineosporiineae subord. nov. and Kineosporiaceae fam. nov. are proposed to accommodate the genera Kineococcus, Kineosporia and Quadrisphaera, Beutenbergiaceae fam. nov. is proposed to accommodate the genera Beutenbergia, Georgenia and Salana and Cryptosporangiaceae fam. nov. is proposed to accommodate the genus Cryptosporangium. The families Nocardiaceae and Gordoniaceae are proposed to be combined in an emended family Nocardiaceae. Emended descriptions are also proposed for most of the other higher taxa.

Pseudosporangium ferrugineum gen. nov., sp. nov., a new member of the family Micromonosporaceae

An actinomycete strain 3-44-a(19)(T) was isolated from sandy soil collected in Bangladesh. The strain formed irregular pseudosporangia directly from aggregated spore chains above the rudimentary aerial mycelium. The pseudosporangia developed singly. Each pseudosporangium contained many small, non-motile, spherical, smooth-surfaced spores in chains. Strain 3-44-a(19)(T) contained meso- and 3-hydroxydiaminopimelic acid in the cell wall and MK-9(H(6)) as the major menaquinone and arabinose, galactose, glucose, mannose, ribose and xylose were present in the whole-cell hydrolysate. The diagnostic phospholipid was phosphatidylethanolamine and iso-C(15 : 0) (24.6 %), C(18 : 1)omega9c (15.5 %), C(16 : 0) (10.6 %), C(18 : 0) (9.4 %), iso-C(16 : 0) (8.6 %) and anteiso-C(15 : 0) (6.0 %) were detected as the major cellular fatty acids. The acyl type of the peptidoglycan was glycolyl and mycolic acids were not detected. The G+C content of the DNA was 73.6 mol%. The chemotaxonomic data indicated that the strain belonged to the family Micromonosporaceae. Phylogenetic analysis based on 16S rRNA gene sequence data also suggested that strain 3-44-a(19)(T) fell within the family Micromonosporaceae. On the basis of phylogenetic analysis and characteristic patterns of 16S rRNA gene signature nucleotides as well as morphological and chemotaxonomic data, this strain should be classified as a member of a new genus and species, Pseudosporangium ferrugineum gen. nov., sp. nov., in the family Micromonosporaceae. The type strain of Pseudosporangium ferrugineum is 3-44-a(19)(T) (=JCM 14710(T) =MTCC9007(T)).

Actinocatenispora sera sp. nov., isolated by long-term culturing

Two novel actinomycete strains, KV-744T and KV-856, were isolated by long-term cultivation. Aerial long-chain spores were produced directly from vegetative mycelia and possessed no motility. Vegetative mycelia developed very well and exhibited fragmentation. The cell-wall peptidoglycan contained meso-diaminopimelic acid, glycine, alanine and glutamic acid, and whole-cell hydrolysates contained arabinose, galactose and xylose. The acyl type of the peptidoglycan was glycolyl. The predominant menaquinone was MK-9(H4) and mycolic acids were not detected. The diagnostic phospholipid was phosphatidylethanolamine. The predominant cellular fatty acids were 14-methylhexadecanoic (ai-C17 : 0), 14-methylpentadecanoic (i-C16 : 0), 15-methylhexadecanoic (i-C17 : 0) and 13-methyltetradecanoic (i-C15 : 0) acids. The G+C content of the DNA was 72–73 mol%. The phenotypic and chemical properties indicated that the two isolates belong to the family Micromonosporaceae and the 16S rRNA gene sequence analysis suggested that the closest relationship was with Actinocatenispora thailandica. The DNA–DNA hybridization values between strain KV-744T or KV-856 and A. thailandica TT2-10T were 42–53 %. Based on the data above, strains KV-744T and KV-856 should be classified as representing a novel species of the genus Actinocatenispora, for which the name Actinocatenispora sera sp. nov. is proposed. The type strain is KV-744T (=NRRL B-24477T=NBRC 101916T).

Luedemannella gen. nov., a new member of the family Micromonosporaceae and description of Luedemannella helvata sp. nov. and Luedemannella flava sp. nov

Three actinomycete strains were isolated from soil samples collected in Bangladesh. The cultures formed spherical sporangia on short sporangiophores directly above the surface of the substrate mycelium. The sporangia developed singly or in clusters and each sporangium contained several nonmotile spherical to oval spores with a smooth surface. The strains 3-9(24)(T), 3-21(27) and 7-40(26)(T) contained meso-diaminopimelic acid in the cell walls, predominant menaquinone MK-9(H(6)) and MK-9(H(4)) and glucose, xylose, galactose, mannose, rhamnose, ribose and arabinose in the whole-cell hydrolysates. Diagnostic phospholipid is phosphatidylethanolamine and branched anteiso-C(17 : 0) (30.0-38.0%), anteiso-C(15 : 0) (12.5-14.0%), iso-C(16 : 0) (10.0-15.0%) and iso-C(15 : 0) (10.0-12.0%) were detected as the major cellular fatty acids. The acyl type of the peptidoglycan was glycolyl and mycolic acids were not detected. The G+C content of the DNA was 71 mol%. The chemotaxonomic data indicate that these strains belong to the family Micromonosporaceae. Phylogenetic analysis based on 16S rRNA gene sequence data suggested that the strains 3-9(24)(T), 3-21(27) and 7-40(26)(T) fall within the family Micromonosporaceae. On the basis of phylogenetic analysis and characteristic patterns of signature nucleotides as well as morphological and chemotaxonomic data, Luedemannella gen. nov. is proposed for our 3 isolates. DNA-DNA hybridization experiment and phenotypic characterization indicated that the new genus was constituted of 2 species, as Luedemannella helvata sp. nov. for the strain 3-9(24)(T) (=JCM 13249(T)=MTCC 8091(T)) and Luedemannella flava for the strain 7-40(26)(T) (=JCM 13250(T)=MTCC 8095(T)) in the family Micromonosporaceae.