Genus Microbispora Research Articles

Microbispora maris sp. nov., a novel actinobacterium isolated from the gill of the leopard coral grouper (Plectropomus leopardus).

A novel actinomycete, designated strain ZYX-F-249T, was isolated from the gill of a leopard coral grouper in Yongxing Island, Hainan Province, China. Based on 16S rRNA gene sequence analysis, strain ZYX-F-249T belonged to the genus Microbispora, with high similarities to Microbispora rosea ATCC 12950T (98.7 %), Microbispora hainanensis 211020T (98.5 %), Microbispora clausenae CLES2T (98.4 %), Microbispora bryophytorum NEAU-TX2-2T (98.1 %) and Microbispora oryzaeRL4-1ST (98.0 %). Phylogenetic analysis of the 16S rRNA gene sequence of strain ZYX-F-249T showed that the strain formed a stable subclade with Microbispora rosea ATCC 12950T in the genus Microbispora. The cell wall of the novel isolate contained meso-diaminopimelic acid, while whole-cell sugars were madurose, glucose and ribose. The predominant menaquinones were MK-9(H6), MK-9(H4), MK-9(H2) and MK-9(H0). The characteristic phospholipids (PLs) were phosphatidylethanolamine, phosphatidylinositol, diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylinositol mannoside, glycophospholipids and an unknown PL. The major cellular fatty acids (>10%) were iso-C16 : 0 and iso-C18 : 0. Genome sequencing showed a DNA G+C content of 71.6%. The low average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values demonstrated that strain ZYX-F-249T could be readily distinguished from closely related species. Based on data from these phylogenetic, chemotaxonomic and physiological characteristics, strain ZYX-F-249T represents a novel species of the genus Microbispora, for which the name Microbispora maris sp. nov. is proposed. The type strain is ZYX-F-249T (=CCTCC AA 2023030T =JCM 36778T).

Whole genome-based reclassification of several species of the genus Microbispora.

The classification of Microbispora, a bacterial genus of significant ecological, agricultural, biotechnological, and clinical importance, has traditionally been carried out based on 16S rRNA gene sequences or phenotypic characteristics, which may lead to equivocal conclusions and it is not in line with the current standards. Moreover, some of the recent species descriptions have not been made using whole genome sequences (WGS), or when used, not all the species were included in the analyses. Consequently, some of the taxonomic conclusions drawn are equivocal, and therefore some currently accepted species should be synonymized. In this study, we revised the taxonomy of the genus Microbispora using digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values, and by reconstructing phylogenetic relationships using whole genome sequences. Based on the clear phylogenomic separations and on the sequence divergence values, we propose to elevate Microbispora rosea subsp. rosea and Microbispora rosea subsp. aerata to the species level, and therefore to create Microbispora aerata sp. nov. with JCM 3076T (= DSM 43176T = ATCC 15448T = IFO 14624T = NBRC 14624T = VKM Ac-1507T) as the type strain. Hence, with this proposition, the correct name for Microbispora rosea subsp. rosea is M. rosea. Furthermore, we propose to reclassify M. camponoti as a subspecies within M. bryophytorum. Consequently, we propose the creation of the following two subspecies: Microbispora bryophytorum subsp. bryophytorum subsp. nov. with DSM 46710T (= CGMCC 4.7138T = NEAU TX2-2T) as the type strain, and Microbispora bryophytorum subsp. camponoti subsp. nov., comb. nov. with DSM 2C-HV3T (= DSM 100527T = CGMCC 4.7281T) as the type strain. In addition, we propose to reinstate M. amethystogenes as an independent species and not as a M. rosea synonym, and reclassify "M. cellulosiformans" as a subspecies within M. amethystogenes. Hence, we propose the creation of the following two subspecies: Microbispora amethystogenes subsp. amethystogenes subsp. nov. with NBRC 101907T (= DSM 43164T = JCM 3021T = NRRL B-2637T) as the type strain, and Microbispora amethystogenes subsp. cellulosiformans subsp. nov., comb. nov. with Gxj-6T (= DSM 109712T = CGMCC 4.7605T) as the type strain. Lastly, we propose M. fusca NEAU-HEGS1-5T and "M. tritici" MT50T as later homotypic synonyms of M. triticiradicis NEAU-HRDPA2-9T.

Microbispora oryzae sp. nov., isolated from leaves of rice plant (Oryza sativa L.).

An endophytic actinomycete, designated strain RL4-1ST, was isolated from surface-sterilized leaves of rice plant (Oryza sativa L.) collected from Buri Rum province, Thailand. Its taxonomic status was determined using a polyphasic approach. Phylogenetic analysis based on the 16S rRNA gene sequences showed that the strain RL4-1ST belongs to the genus Microbispora and is most closely related to Microbispora rosea subsp. rosea ATCC 12950T (98.5%). The strain forms pairs of spores on short sporophores borne on the aerial mycelium. Polar lipid profile of strain RL4-1ST is diphosphatidylglycerol, hydroxy-phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides, ninhydrin-positive glycophospholipid, two unidentified phospholipids, an unidentified aminolipid, and an unidentified glycolipid. MK-9(H4), MK-9(H2), and MK-9 are major menaquinones of this organism. The predominant cellular fatty acids are iso-C16:0, C17:0 and C16:0. Strain RL4-1ST contains meso-diaminopimelic acid, glucose, madurose and ribose in whole-cell hydrolysates. The draft genome of strain RL4-1ST consists of 7.46 Mbp and has a G + C content 71.2 mol%. Digital DNA-DNA hybridization and average nucleotide identity values between the genome sequence of strain RL4-1ST with Microbispora rosea subsp. rosea ATCC 12950T are 26.0% and 80.7%, respectively. Based on data of genotypic, phenotypic, phylogenetic and chemotaxonomic analysis, strain RL4-1ST represents a novel species of the genus Microbispora, for which the name Microbispora oryzae sp. nov. is proposed. The type strain is RL4-1ST (=TBRC 14817T = NBRC 115115T).

Microbispora cellulosiformans sp. nov., a novel actinomycete with cellulase activity isolated from soil in the cold region.

A novel cellulase-producing actinomycete strain Gxj-6T, isolated from soil in the cold region (Heihe city, Heilongjiang province, the northernmost part of China), subjected to a taxonomic study using a polyphasic approach. In the neighbour-joining phylogenetic tree based on 16S rRNA gene sequences, strain Gxj-6T fell within the clade comprising the type strains of species of the genus Microbispora. 16S rRNA gene sequence similarity studies exhibited that species Gxj-6T was most closely related to Microbispora bryophytorum NEAU-TX2-2T (99.45%), Microbispora fusca NEAU-HEGS1-5T (99.41%), Microbispora camponoti 2C-HV3T (99.31%) and Microbispora rosea subsp. rosea JCM 3006T (98.68%). Organism Gxj-6T contained MK-9(H2) as the predominant ubiquinone and C18:0 10-methyl as the major fatty acid. The major polar lipids of culture Gxj-6T were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol mannoside, three unidentified phospholipids, two unidentified glycolipids and two unidentified lipids. The DNA G+C content of strain Gxj-6T was 71.25mol%. The morphological and chemotaxonomic properties of the strain are also consistent with those members of the genus Microbispora. Combinated with the lower DNA-DNA relatedness values, phenotypic properties, physiology and biochemistry distinctiveness with other recognized species strains, revealed that strain Gxj-6T is separated from other phylogenetically closely species of the genus Microbispora. Therefore, strain Gxj-6T is considered to represent a novel species of the genus Microbispora, for which the name Microbispora cellulosiformans sp. nov. is proposed. The type strain is Gxj-6T (= CGMCC 4.7605T = DSM 109712T).

A novel diterpene agent isolated from Microbispora hainanensis strain CSR-4 and its in vitro and in silico inhibition effects on acetylcholine esterase enzyme

An actinomycete strain CSR-4 was isolated from the rhizosphere soil of Zingiber montanum. Taxonomic characterization revealed strain CSR-4 was a member of the genus Microbispora. Whole-genome sequence analysis exhibited the highest average nucleotide identity (ANI) value (95.34%) and digital DNA–DNA hybridization (DDH) value (74.7%) between strain CSR-4 and the closest relative M. hainanensis DSM 45428T, which was in line with the assignment to same species. In addition, a new diterpene compound, 2α-hydroxy-8(14), 15-pimaradien-17, 18-dioic acid, and nine known compounds were isolated from the ethyl acetate crude extract of fermentation broth. Interestingly, a new diterpene displayed the suppressive effect on the recombinant human acetylcholinesterase (rhAChE) enzymes (IC50 96.87 ± 2.31 μg/ml). In silico studies based on molecular docking and molecular dynamics (MD) simulations were performed to predict a binding mode of the new compound into the binding pocket of the rhAChE enzyme and revealed that some amino acids in the peripheral anions site (PAS), anionic subsite, oxyanion site and catalytic active site (CAS) of the rhAChE have interacted with the compound. Therefore, our new compound could be proposed as a potential active human AChE inhibitor. Moreover, the new compound can protect significantly the neuron cells (% neuron viability = 88.56 ± 5.19%) from oxidative stress induced by serum deprivation method at 1 ng/ml without both neurotoxicities on murine P19-derived neuron cells and cytotoxicity against Vero cells.

Isolation and 16S rRNA gene sequences analysis of thermophilic Actinobacteria isolated from soil in Cisolok geothermal area, West Java, Indonesia

The thermophilic Actinobacteria are known not only as producers of pharmaceutically important bioactive compounds, but also commercially important enzymes, yet their diversity in geothermal area in Indonesia have been rarely reported. In our previous study, a new thermophilic Actinobacteria genus belonging to the family Pseudonocardiaceae has been isolated from soil in Cisolok geothermal area. This current study reports the taxonomy and findings of potentially new taxa of thermophilic Actinobacteria, based on phylogenetic analysis of 16S rRNA gene sequences. Twenty-five isolates of thermophilic Actinobacteria were isolated from soil samples and maintained using previously described methods. The 16S rRNA gene sequence-similarity search against all related species was performed using EzTaxon-e database. The sequences of 25 isolates showed similarity to member of family Streptomycetaceae (genus Streptomyces; 10 isolates), Thermomonosporaceae (genus Actinomadura; 3 isolates), Streptosporangiaceae (genus Microbispora; 6 isolates), Micromonosporaceae (genus Micromonospora; 2 isolates), Pseudonocardiaceae (genus Amycolatopsis; 3 isolates), and Nocardiaceae (genus Nocardia; 1 isolate). Fifteen out of 25 isolates are belong to non-Streptomycetaceae family, thus regarded as rare Actinobacteria. Nineteen out of 25 isolates showed 16S rRNA gene sequence-similarity values 97 – 99% to their closely related species, suggested the potential for findings novel taxa of thermophilic Actinobacteria from Cisolok geothermal area.

Microbispora fusca sp. nov., a novel actinomycete isolated from the ear of wheat (Triticum aestivum L.).

A novel actinomycete, designated strain NEAU-HEGS1-5T, was isolated from the ear of wheat (Triticum aestivum L.) and characterized using a polyphasic approach. The morphological and chemotaxonomic characteristics of the strain coincided with those of members of the genus Microbispora. The results of 16S rRNA gene sequence analysis showed that the isolate was most closely related to Microbispora bryophytorum NEAU-TX2-2T (99.3 %), Microbispora camponoti 2C-HV3T (99.2 %), Microbispora amethystogenes JCM 3021T (99.1 %) and Microbispora rosea subsp. rosea JCM 3006T (98.5 %). However, two tree-making algorithms supported the position that strain NEAU-HEGS1-5T formed a distinct clade with M. bryophytorum NEAU-TX2-2T, M. camponoti 2C-HV3T and M. rosea subsp. rosea JCM 3006T. Furthermore, multilocus sequence analysis based on the 16S-gyr B-rpo B genes and a combination of DNA-DNA hybridization results and some physiological and biochemical properties demonstrated that the strain could be distinguished from its closest relatives. Therefore, it is proposed that strain NEAU-HEGS1-5T should be classified as representative of a novel species of the genus Microbispora, for which the name Microbispora fusca sp. nov. is proposed. The type strain is NEAU-HEGS1-5T (=CCTCC AA 2019030T=DSM 104648T).

Microbispora sitophila sp. nov., a novel actinobacterium isolated from rhizosphere soil of wheat (Triticum aestivum L.).

A novel actinobacterium, designated strain NEAU-D428T, was isolated from rhizosphere soil of wheat and characterized using a polyphasic approach. Morphological and chemotaxonomic characteristics of the strain coincided with members of the genus Microbispora. The 16S rRNA gene sequence analysis showed that the isolate was most closely related to Microbispora bryophytorum NEAU-TX2-2T (99.2 %). Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the strain clustered with Microbispora clausenae CLES2T (99.1 %), but formed a separate subclade in the phylogenomic tree within the genus Microbispora. The menaquinones were identified as MK-9(H4), MK-9(H2) and MK-9(H0). The phospholipid profile was found to consist of diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, ninhydrin-positive glycophospholipid, phosphatidylinositol and phosphatidylinositol mannoside. The major fatty acids were identified as iso-C16 : 0, C16 : 0, 10-methyl C17 : 0 and C18 : 0. Digital DNA-DNA hybridization and average nucleotide identity values between strain NEAU-D428T and M. bryophytorum NEAU-TX2-2T, Microbispora camponoti 2C-HV3T, M. clausenae CLES2T, 'Microbispora cellulosiformans' Gxj-6T and Microbispora fusca NEAU-HEGS1-5T were 47.6 and 92.2 %, 47.5 and 92.2 %, 55.9 and 94.0 %, 33.1 and 86.8 %, and 33.6 and 87.1 %, respectively. These results and some physiological and biochemical properties demonstrated that the strain could be distinguished from its closest relatives. Therefore, it is proposed that strain NEAU-D428T should be classified as representative of a novel species of the genus Microbispora, for which the name Microbispora sitophila sp. nov. is proposed. The type strain is NEAU-D428T (=CGMCC 4.7523T=DSM 109822T).

Microbispora tritici sp. nov., a novel actinomycete isolated from a root of wheat (Triticum aestivum L.).

A novel actinomycete, designated strain NEAU-HRGS1-13T, was isolated from a root of wheat (Triticum aestivum L.) and characterised using a polyphasic approach. Morphological and chemotaxonomic characteristics were consistent with those of members of the genus Microbispora. The major menaquinones were identified as MK-9(H2) and MK-9(H4) and the whole cell hydrolysates found to contain meso-diaminopimelic acid and madurose. The phospholipid profile was found to consist of diphosphatidylglycerol, a ninhydrin-positive glycophospholipid, phosphatidylinositol mannosides, phosphatidylmonomethylethanolamine, an unidentified glycolipid and an unidentified lipid. The major fatty acids were identified as iso-C16:0, C16:0, 10-methyl C17:0, C18:0 and C17:0. The 16S rRNA gene sequence analysis showed that the isolate is closely related to Microbispora triticiradicis NEAU-HRDPA2-9T (99.4%), Microbispora bryophytorum NEAU-TX2-2T (99.0%), Microbispora camponoti 2C-HV3T (98.8%), Microbispora hainanensis DSM 45428T (98.8%), Microbispora amethystogenes JCM 3021T (98.6%), Microbispora siamensis NBRC 104113T (98.5%), Microbispora corallina JCM 10267T (98.3%) and Microbispora rosea subsp. rosea JCM 3006T (98.2%). However, DNA-DNA relatedness and cultural, physiological and biochemical data showed that strain NEAU-HRGS1-13T can be distinguished from its close relatives. Therefore, it is concluded that strain NEAU-HRGS1-13T represents a novel species of the genus Microbispora, for which the name Microbispora tritici sp. nov. is proposed. The type stain is NEAU-HRGS1-13T (= CGMCC 4.7402T = DSM 104650T).

Microbispora soli sp. nov., isolated from soil of a hot spring.

A novel actinomycete, strain RTBAU4-9T, which produced longitudinally paired spores on aerial mycelia, was isolated from a soil sample of a hot spring area. This strain exhibited chemotaxonomic and genotypic properties typical of the genus Microbispora, such as meso-diaminopimelic acid in the cell-wall peptidoglycan, glucose, ribose and trace amount of madurose as the characteristic whole-cell sugars, phosphatidylethanolamine, diphosphatidylglycerol and phosphoglycolipids as the membrane phospholipids, MK-9(H4), MK-9(H2) and MK-9(H0) as the characteristic menaquinones, and iso-C16 : 0 and anteiso-C17 : 0 as the main fatty acids. The G+C content of the genomic DNA was 70.2 mol%. The result of 16S rRNA gene sequence analysis revealed the strain was a member of the genus Microbispora and was most closely related to Microbispora hainanensis 211020T (98.3 % 16S rRNA gene sequence similarity). In addition, the low percentage of DNA-DNA relatedness (<28.1±1.2 %) and several phenotypic differences confirmed that strain RTBAU4-9T should be considered as representing a novel species of the genus Microbispora, for which the name Microbispora soli sp. nov. is proposed. The type strain is RTBAU4-9T (=TBRC 7648T=NBRC 113147T).

Microbispora triticiradicis sp. nov., a novel actinomycete isolated from the root of wheat (Triticum aestivum L.).

A novel actinomycete, designated strain NEAU-HRDPA2-9T, was isolated from the roots of wheat (Triticumaestivum L.) and characterized using a polyphasic approach. The morphological and chemotaxonomic characteristics of the strain coincided with those of members of the genus Microbispora. The 16S rRNA gene sequence analysis showed that the isolate was most closely related to Microbispora bryophytorum NEAU-TX2-2T (98.6 %), Microbispora hainanensis DSM 45428T (98.5 %), Microbispora camponoti 2C-HV3T (98.5 %), Microbispora amethystogenes JCM 3021T (98.2 %), Microbispora siamensis NBRC 104113T (98.1 %), Microbispora corallina JCM 10267T (98.0 %) and Microbispora roseasubsp.rosea JCM 3006T (97.9 %). However, two tree-making algorithms supported the position that strain NEAU-HRDPA2-9T formed a distinct clade with M. siamensis NBRC 104113T and M. hainanensis DSM 45428T. Furthermore, a combination of DNA-DNA hybridization results and some physiological and biochemical properties demonstrated that the strain could be distinguished from its closest relatives. Therefore, it is proposed that strain NEAU-HRDPA2-9T should be classified as representative of a novel species of the genus Microbispora, for which the name Microbisporatriticiradicis sp. nov. is proposed. The type strain is NEAU-HRDPA2-9T (=CGMCC 4.7399T=DSM 104649T).

Molecular-signature analyses support the establishment of the actinobacterial genus Sphaerimonospora (Mingma et al. 2016)

The genera Microbispora and Sphaerimonospora were examined for GyrB and RecA amino-acid signatures to determine whether molecular-signature analyses support the recent establishment of the genus Sphaerimonospora. The creation of Sphaerimonospora was based mainly upon morphological differences between Microbispora and Sphaerimonospora and the clustering of the type strains of the two genera in phylogenetic trees based on a multilocus sequence analysis. The molecular-signature analyses showed that all members of Sphaerimonospora can be distinguished from all members of Microbispora at 14 amino acid positions in the GyrB protein and at four positions in the shorter RecA protein. These amino acid differences can be used as signatures to differentiate the members of these genera from each other and thus provide support for the establishment of the genus Sphaerimonospora. This is the first demonstration of the use of molecular signatures to support the establishment of a new genus in the family Streptosporangiaceae. Following the transfer of Microbispora mesophila and Microbispora thailandensis from Microbispora to Sphaerimonospora, all species in the genus Microbispora are characterised by the insertion of a small, hydrophobic amino acid after position 208 in the GyrB protein. This insertion is absent from the GyrB protein of members of the genus Sphaerimonospora.

16S-gyrB-rpoB multilocus sequence analysis for species identification in the genus Microbispora.

The genus Microbispora has been considered difficult to define taxonomically. While 16S rRNA gene analysis is required to determine phylogenetic relationships among species in this genus, most 16S rRNA gene-based phylogenetic tree topologies are not reliable. The genus Microbispora currently contains eight species along with six reclassified species (Microbispora chromogenes, Microbispora diastatica, Microbispora parva, Microbispora indica, Microbispora karnatakensis, Microbispora rosea) and Microbispora rosea subsp. aerata, a taxon composed of three further reclassified species (Microbispora aerata, Microbispora thermodiastatica, and Microbispora thermorosea). 16S rRNA, 23S rRNA, gyrB, and rpoB gene sequences were obtained for the type strains of Microbispora species, and eleven endophytic isolates from a Brazilian medicinal plant, Vochysia divergens. Using the concatenated sequence, most Microbispora type strains could be distinguished with high probability support. Based on these analyses, we propose that five of the species reclassified within the subspecies of M. rosea (M. chromogenes, M. karnatakensis, M. parva, M. aerata and M. thermorosea) are distinct from M. rosea and so should be retained as distinct species. The concatenated 16S-gyrB-rpoB gene phylogenic tree had significant probability support and topology. We propose the use of concatenated 16S-gyrB-rpoB gene sequences to determine phylogenetic relationships within the genus Microbispora. We also suggest that strains sharing >98.1% 16S-gyrB-rpoB gene sequences similarity be defined as a single species, based on results from this analysis. Seven of the strains isolated from V. divergens were not related to any previously described Microbispora species.

Proposal of Sphaerimonospora cavernae gen. nov., sp. nov. and transfer of Microbispora mesophila (Zhang et al., 1998) to Sphaerimonospora mesophila comb. nov. and Microbispora thailandensis (Duangmal et al., 2012) to Sphaerimonospora thailandensis comb. nov.

The actinomycete strain N74T, isolated from cave soil, was studied using a polyphasic taxonomic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain N74T formed a stable, distinct lineage cluster together with Microbispora thailandensis NN276T (99.3% similarity) and Microbispora mesophila JCM 3151T (97.5%). Strain N74T was observed to produce single spherical spores on aerial mycelium as reported for M. mesophila JCM 3151T and M. thailandensis NN276T but different from other known species of the genus Microbispora, which are characterized by pairs of spores on aerial hyphae. Multilocus sequence analyses based on concatenated partial gyrB, rpoB, atpD, recA and 16S rRNA gene sequences showed a clear distinction of strain N74T, M. mesophila JCM 3151T and M. thailandensis NN276T from other members of the genus Microbispora, although the chemotaxonomic characteristics of strain N74T were similar to the genus Microbispora; the cell wall contained meso-diaminopimelic acid and the whole-cell hydrolysate contained madurose as the diagnostic sugar. The major menaquinone was MK-9(H4). The fatty acid profile contained iso-C16:0. On the basis of morphological, chemotaxonomic and phylogenetic evidence, strain N74T is assigned to a novel species of a new genus, for which the name Sphaerimonospora cavernae gen. nov., sp. nov. is proposed. The type strain of Sphaerimonospora cavernae is N74T (=BCC 77604T=NBRC 111481T). It is also proposed that M. mesophila and M. thailandensis be transferred to this genus as Sphaerimonospora mesophila comb. nov. (type strain JCM 3151T=NBRC 14179T=DSM 43048T) and Sphaerimonospora thailandensis comb. nov. (type strain NN276T=BCC 41490T=NBRC 107569T), respectively.

Microbispora camponoti sp. nov., a novel actinomycete isolated from the cuticle of Camponotus japonicus Mayr.

A novel actinomycete, designated strain 2C-HV3(T), was isolated from the cuticle of Camponotus japonicus Mayr collected from Harbin, Heilongjiang province, north China and characterised using a polyphasic approach. The 16S rRNA gene sequence of strain 2C-HV3(T) showed that it has high sequence similarities with Microbispora bryophytorum NEAU-TX2-2(T) (99.9 %), Microbispora amethystogenes JCM 3021(T) (98.9 %) and Microbispora rosea subsp. rosea JCM 3006(T) (98.6 %). Phylogenetic analysis based on 16S rRNA and gyrB gene sequences demonstrated that strain 2C-HV3(T) clusters with M. bryophytorum NEAU-TX2-2(T) using two tree-making algorithms. Moreover, key morphological and chemotaxonomic properties also confirmed the affiliation of strain 2C-HV3(T) to the genus Microbispora. Longitudinal paired spores were observed to be born on short sporophores branching from the aerial hyphae. The cell wall was found to contain meso-diaminopimelic acid as the diagnostic diamino acid; madurose was found in the whole cell hydrolysate. The polar lipid profile was found to consist of diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositolmannoside, ninhydrin-positive glycophospholipids, an unidentified phospholipid and an unidentified glycolipid. The predominant menaquinones were identified as MK-9(H2) and MK-9(H4). The major fatty acids were identified as 10-methyl C17:0 and iso-C16:0. However, a combination of DNA-DNA hybridization results and some phenotypic characteristics demonstrated that strain 2C-HV3(T) can be distinguished from its closely related relatives. Consequently, it is proposed that strain 2C-HV3(T) represents a new species of the genus Microbispora, for which the name Microbispora camponoti sp. nov. is proposed. The type strain is 2C-HV3(T) (=CGMCC 4.7281(T) = DSM 100527(T)).

Brominated Variant of the Lantibiotic NAI-107 with Enhanced Antibacterial Potency.

We identified an Actinoallomurus strain producing NAI-107, a chlorinated lantibiotic effective against multidrug-resistant Gram-positive pathogens and previously reported from the distantly related genus Microbispora. Inclusion of KBr in the production medium of either the Actinoallomurus or the Microbispora producer readily afforded brominated variants of NAI-107, which were designated as NAI-108. The other post-translational modifications naturally occurring in this lantibiotic family (i.e., hydroxylation of Pro-14 and C-terminal decarboxylation) were unaffected by the presence of a brominated tryptophan. In addition to being the first example of a bromine-containing lantibiotic, NAI-108 displayed a small but consistent improvement in antibacterial activity against all tested strains. The brominated lantibiotic maintained the same rapid bactericidal activity as NAI-107 but at reduced concentrations, consistent with its increased potency and with the role played by the hydrophobicity of the first lanthionine ring. NAI-108 thus represents an interesting addition to a promising family of potent and effective lantibiotics.

Microbispora bryophytorum sp. nov., an actinomycete isolated from moss (Bryophyta).

A novel endophytic actinomycete, designated strain NEAU-TX2-2(T), was isolated from moss and characterized using a polyphasic approach. The isolate was found to have morphological characteristics typical of the genus Microbispora . The isolate formed longitudinally paired spores on the tips of short sporophores that branched from aerial hyphae. Analysis of the 16S rRNA gene sequence supported the assignment of the novel strain to the genus Microbispora , and strain NEAU-TX2-2(T) exhibited 99.08 and 98.62% gene sequence similarities to Microbispora amethystogenes JCM 3021(T) and Microbispora rosea subsp. rosea JCM 3006(T), respectively. However two tree-making algorithms supported the position that strain NEAU-TX2-2(T) formed a distinct clade with M. rosea subsp. rosea JCM 3006(T). A low level of DNA-DNA relatedness allowed the isolate to be differentiated from M. amethystogenes JCM 3021(T) and M. rosea subsp. rosea JCM 3006(T). Moreover, strain NEAU-TX2-2(T) could also be distinguished from its closest phylogenetic relatives by morphological and physiological characteristics. Therefore, it is proposed that strain NEAU-TX2-2(T) represents a novel species of the genus Microbispora for which the name Microbispora bryophytorum sp. nov. is proposed. The type strain is NEAU-TX2-2(T) ( = CGMCC 4.7138(T) = DSM 46710(T)).

Linfuranone A, a new polyketide from plant-derived Microbispora sp. GMKU 363

Actinomycetes are well-known producers of an enormous variety of secondary metabolites, many of which have beneficial applications in the field of medicine and agriculture. More recently, endophytic actinomycetes residing in plants revealed the potential sources of biodiversity carrying a variety of bioactive metabolites and acting as potential biocontrol agents.1–3 Particularly, endophytic actinomycetes isolated from tropical plants have been examined to possess significant biosynthetic potential, particularly polyketide synthase and nonribosomal peptide synthetase genes.4 We have recently reported a new polyketide compound from an endophytic actinomycete isolated from a Thai medicinal plant collected at the Eastern Botanical Garden (Khao Hin Son), Chachoengsao province, Thailand.5 Here, we now report a new furanone-containing polyketide, linfuranone A (Figure 1), produced by an endophytic actinomycete isolated from a Thai medicinal plant collected at the same location. An endophytic Microbispora sp. GMKU363 was isolated from a root of Thai medicinal plant ‘Lin Ngu Hao’ (Clinacanthus siamensis Bremek.) according to the reported protocol.6 The strain was identified as a member of the genus Microbispora on the basis of 99.9% 16S ribosomal RNA gene sequence identity (1387 nucleotides; GenBank accession number GU459171) with the Microbispora mesophila JCM 3151T type strain (accession number AF002266). Strain GMKU363 was cultured on Bn-2 slant agar medium consisting of soluble starch 0.5%, glucose 0.5%, meat extract (Kyokuto Pharmaceutical Industrial Co., Ltd., Tokyo, Japan) 0.1%, yeast extract (Difco Laboratories, Detroit, MI, USA) 0.1%, NZ-case (Wako Pure Chemical Industries, Ltd., Osaka, Japan) 0.2%, NaCl 0.2%, CaCO3 0.1%, agar 1.5% and was inoculated into 500-ml K-1 flasks each containing 100ml of the V-22 seed medium (pH 7.0) consisting of soluble starch 1%, glucose 0.5%, NZ-case 0.3%, yeast extract 0.2%, triptone (Difco Laboratories) 0.5%, K2HPO4 0.1%, MgSO4 � 7H2O 0.05% and CaCO3 0.3%. The cultures were cultivated on a rotary shaker (200 r.p.m.) at 30 1C for 4 days. The seed culture (3ml) was transferred into 500-ml K-1 flasks each containing 100ml of the A-11M production medium (pH 7.0) consisting of soluble starch 2.5%, glucose 0.2%, yeast extract 0.5%, polypeptone (Wako Pure Chemical Industries, Ltd.) 0.5%, NZ-amine 0.5%, CaCO3 0.3% and Diaion HP-20 (Mitsubishi Chemical Co.) 1%. The cultures inoculated in flasks were cultured on a rotary shaker (200 r.p.m.) at 30 1C for 6 days, and the whole culture broth was extracted with 100ml of 1butanol on each flask by shaking for an additional hour. The organic layer was evaporated to give 3.0 g of crude extract from 1.5 l of culture. The crude extract (3.0 g) was subjected to silica gel column chromatography with a step gradient of CHCl3-MeOH (1:0, 20:1, 10:1, 4:1, 2:1, 1:1 and 0:1 v/v). The concentration of the fraction eluted with a 2:1 mixture of CHCl3-MeOH provided 0.23 g of dark viscous oil, which was further purified by preparative HPLC (Cosmosil AR-II, San Diego, CA, USA, 250� 10mm2) using 30%MeCN in distilled water at 4mlmin�1 to give linfuranone A (2.0mg, tR1⁄4 12.1min). Linfuranone A (Figure 1) was obtained as an optically active ([a]D �9.9 (c 0.16, MeOH)), colorless and amorphous compound that gave an [MþNa]þ peak at m/z 417.2257 in the high resolution electrospray ionization time-of-flight mass spectrometry appropriate for a molecular formula of C22H34O6, (calculated for C22H34O6Na, 417.2248), which was consistent with the 1H and 13C NMR data (Table 1). The IR spectrum of linfuranone A showed absorption bands for hydroxyl (3333 cm�1) and carbonyl (1691 cm�1) functionalities. The UV spectrum showed absorption maxima at 282 (e 23600) and 232 (e 75300) in MeOH. 13C NMR and HMQC spectral data confirmed the presence of 22 carbons, which were assigned to two oxygenated-quaternary sp2 carbons, seven olefinic carbons (five are proton-bearing), one quaternary sp3 carbon, four sp3 methines (three are oxygen-bearing), three sp3 methylenes and five methyl carbons. Analysis of the COSY spectrum led to the identification of four proton-bearing fragments, H-17–H-19, H-15/H-14/H-21, H-12/H-13 and H-6–H-11 (Figure 1). HMBC correlations were detected from the

Microbispora thailandensis sp. nov., an actinomycete isolated from cave soil

The taxonomic position of actinomycete strain NN276(T), isolated from cave soil, was studied using the polyphasic taxonomic approach. A phylogenetic tree based on 16S ribosomal RNA (rRNA) gene sequences showed that the isolate formed a distinct evolutionary linage with the genus Microbispora, with M. mesophila JCM 3151(T) as its closest phylogenetic neighbor (97.9% similarity). The organism contained meso-diaminopimelic acid and the N-acetyl type of peptidoglycan. Madurose was detected in the whole-cell hydrolasate. The predominant menaquinones were MK-9(H(4)), MK-9(H(2)) and MK-9. Mycolic acids were not detected. Major phospholipids were diphosphatidylglycerol, hydroxy-phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The major cellular fatty acid was iso-C(16: 0) and G+C content 70 mol%. DNA-DNA hybridization demonstrated that the isolate was distinct from M. mesophila JCM 3151(T). On the basis of phenotypic and genotypic data, it is proposed that strain NN276(T) represents a novel species of the genus Microbispora, hence the name Microbispora thailandensis sp. nov. The type strain is strain NN276(T) (=BCC 41490(T)=NRRL B-24806(T)=NBRC 107569(T)).

Microbispora siamensis sp. nov., a thermotolerant actinomycete isolated from soil

An actinomycete, strain DMKUA 245(T), isolated from soil, was investigated using a polyphasic approach. The isolate formed longitudinally paired spores on the tips of short sporophores that branched alternately from aerial hyphae. The morphological and chemotaxonomic properties clearly demonstrated that the new isolate belonged to the genus Microbispora. 16S rRNA gene sequence analysis supported the assignment of the novel strain to the genus Microbispora. The gene sequence similarity values between the novel strain and the closely related species Microbispora corallina, Microbispora rosea subsp. rosea, Microbispora rosea subsp. aerata and Microbispora amethystogenes were 98.4 %, 97.4 %, 97.0 % and 96.9 %, respectively. The DNA-DNA hybridization values and some physiological and biochemical properties indicated that strain DMKUA 245(T) could be distinguished from its phylogenetically closest relatives. Based on these genotypic and phenotypic data, strain DMKUA 245(T) represents a novel species in the genus Microbispora for which the name Microbispora siamensis sp. nov. is proposed. The type strain is strain DMKUA 245(T) (=BCC 14407(T)=NBRC 104113(T)). In addition, DNA-DNA relatedness values in reciprocal hybridization experiments showed that M. amethystogenes was a separate genomic species from M. rosea subsp. rosea. A combination of genotypic and phenotypic data supported the classification of M. amethystogenes as a separate species.