Streptomyces mahasarakhamensis sp. nov., an Endophytic Actinobacterium Isolated from Jasmine Rice and its Potential as plant Growth Promoter.

Two endophytic actinobacteria, strains MK5T and MK7, were isolated from the surface-sterilized root of Jasmine rice (Oryza sativa KDML 105). These strains were aerobic actinobacteria with a well-developed substrate and aerial mycelia that formed spiral spore chains. The type strains that shared the high 16S rRNA gene sequence similarity with both strains were Streptomyces naganishii NBRC 12892T (99.4%), "Streptomyces griseicoloratus" TRM S81-3T (99.2%), and Streptomyces spiralis NBRC 14215T (98.9%). Strains MK5T and MK7 are the same species sharing a digital DNA-DNA hybridization (dDDH) value of 95.3% and a 16S rRNA gene sequence similarity of 100%. Chemotaxonomic data confirmed the affiliation of strains MK5T and MK7 to the genus Streptomyces. Strains MK5T and MK7 contained MK-9(H4) as a major menaquinone; the whole-cell sugar of both strains was galactose and glucose. The strain MK5T shared 93.4% average nucleotide identity (ANI)-Blast, 95.5% ANI-MUMmer, 93% average amino acid identity, and 61.3% dDDH with S. spiralis NBRC 14215T. The polyphasic approach confirmed that strain MK5T represents a novel species, and the name Streptomyces mahasarakhamensis sp. nov. is proposed. The type strain is MK5T (= TBRC 17754 = NRRL B-65683). Genome mining, using an in silico approach and searching biosynthesis gene clusters of strains MK5T and MK7, revealed that the genomes contained genes encoding proteins relating to plant growth promotion, bioactive compounds, and beneficial enzymes. Strains MK5T and MK7 could produce indole acetic acid and solubilize phosphate in vitro.

Description of Streptomyces naphthomycinicus sp. nov., an endophytic actinobacterium producing naphthomycin A and its genome insight for discovering bioactive compounds.

Endophytic actinobacteria are a group of bacteria living inside plant tissue without harmful effects, and benefit the host plant. Many can inhibit plant pathogens and promote plant growth. This study aimed to identify a strain of Streptomyces as a novel species and study its antibiotics production. An endophytic actinobacterium, strain TML10T was isolated from a surface-sterilized leaf of a Thai medicinal plant (Terminalia mucronata Craib and Hutch). As a result of a polyphasic taxonomy study, strain TML10T was identified as a member of the genus Streptomyces. Strain TML10T was an aerobic actinobacterium with well-developed substrate mycelia with loop spore chains and spiny surface. Chemotaxonomic data, including cell wall components, major menaquinones, and major fatty acids, confirmed the affiliation of strain TML10T to the genus Streptomyces. The results of the phylogenetic analysis, including physiological and biochemical studies in combination with a genome comparison study, allowed the genotypic and phenotypic differentiation of strain TML10T and the closest related type strains. The digital DNA-DNA hybridization (dDDH), Average nucleotide identity Blast (ANIb), and ANIMummer (ANIm) values between strain TML10T and the closest type strain, Streptomyces musisoli CH5-8T were 38.8%, 88.5%, and 90.8%, respectively. The name proposed for the new species is Streptomyces naphthomycinicus sp. nov. (TML10T = TBRC 15050T = NRRL B-65638T). Strain TML10T was further studied for liquid and solid-state fermentation of antibiotic production. Solid-state fermentation with cooked rice provided the best conditions for antibiotic production against methicillin-resistant Staphylococcus aureus. The elucidation of the chemical structures from this strain revealed a known antimicrobial agent, naphthomycin A. Mining the genome data of strain TML10T suggested its potential as a producer of antbiotics and other valuable compounds such as ε-Poly-L-lysine (ε-PL) and arginine deiminase. Strain TML10T contains the arcA gene encoding arginine deiminase and could degrade arginine in vitro.

Distribution of Blastocystis subtypes isolated from various animal hosts in Thailand.

Blastocystis is a parasitic protist of a variety of hosts, including humans. Mapping the distribution of Blastocystis and its genetic variants across different host species can help us understand the epidemiology of this organism and its role in health and disease. This study aimed to identify subtypes of Blastocystis detected in different animal hosts in Thailand. A total of 825 fecal samples belonging to 18 vertebrate orders, 36 families, 68 genera, and 80 species were collected. Of these, 111 specimens were Blastocystis-positive by culture. Seventy-nine samples were subjected to small subunit (SSU) ribosomal DNA amplification by PCR, and reliable subtype data were obtained for 61 specimens. At least 14 subtypes (ST), namely ST1 to ST10, ST14/ST24/ST25 complex, ST23, ST26, and ST29 were detected. In addition, Blastocystis was found in tortoises. ST1 (3.2%) and ST5 (11.5%) were found in pigs, ST2 (1.6%) and ST3 (3.2%) in non-human primates, ST4 (14.7%) in rodents and ruminants, ST6 (4.9%), ST7 (30%), ST9 (1.6%), and ST29 (1.6%) in birds, ST8 (6.6%) in Green peafowl and East Asian Porcupine, and ST10 (4.9%), ST14/ST24/ST25 (9.8%), ST23 (1.6%) and ST26 (1.6%) in ruminants. The sequence recovered from the elongated tortoises (Indotestudo elongata) (3.2%) was phylogenetically placed within the reptilian cluster of Blastocystis, for which no subtype system is available yet. Of note, we did not obtain Blastocystis sequences from any of the many canids and felids sampled in the study, and our data are in support of host specificity of Blastocystis, according to both colonization and subtype distribution.

Streptomyces phytophilus sp. nov., an endophytic actinobacterium with biosynthesis potential as an antibiotic producer.

An endophytic actinobacterium, strain PIP175T, was isolated from the root sample of a native apricot tree (Pittosporum angustifolium) growing on the Bedford Park campus of Flinders University, Adelaide, South Australia. This strain is a Gram stain-positive, aerobic actinobacterium with well-developed substrate mycelia. Aerial mycelia rarely produce spores and the spore chain is spiral. Strain PIP175T showed the highest 16S rRNA gene sequence similarity to Streptomyces aculeolatus DSM 41644T (99.4 %). Other closely related phylogenetic representatives include Streptomyces synnematoformans DSM 41902T (98.3 %), Streptomyces albospinus NBRC 13846T (97.6 %), Streptomyces cacaoi subsp. cacaoi NRRL B-1220T (97.5 %) and Streptomyces ruber NBRC 14600T (97.4 %). The major cellular fatty acid of this strain was iso-C16 : 0 and the major menaquinone was MK-9(H6). The whole-cell sugar contained galactose, glucose and mannose. Chemotaxonomic data confirmed that strain PIP175T belonged to the genus Streptomyces. Digital DNA-DNA hybridization, average nucleotide identity based on blast and OrthoANIu results between strain PIP175T and S. aculeolatus DSM 41644T were 60.0, 94.1 and 94.9 %, respectively. Genotypic and phenotypic data and genome analysis results allowed the differentiation of strain PIP175T from its closest species with validly published names. Strain PIP175T showed good activity against methicillin-resistant Staphylococcus aureus 03120385. Genome mining of strain PIP175T revealed biosynthetic genes encoding proteins relating to antibiotic production, plant growth promotion and biodegradation enzymes. The name proposed for the new species is Streptomyces phytophilus sp. nov. The type strain is PIP175T (=DSM 103379T=TBRC 6026T).

Streptomyces spinosus sp. nov. and Streptomyces shenzhenensis subsp. oryzicola subsp. nov. endophytic actinobacteria isolated from Jasmine rice and their genome mining for potential as antibiotic producers and plant growth promoters.

Two endophytic actinobacteria, strains SBTS01T and W18L9T, were isolated from leaf sheath and leaf tissue, respectively, of Jasmine rice (Oryza sativa KDML 105) grown in a rice paddy field in Roi Et Province, Thailand. A polyphasic taxonomic study showed that both strains belong to the genus Streptomyces; they are aerobic, forming well-developed substrate mycelia and aerial mycelia with long chains of spores. Strain SBTS01T shares high 16S rRNA gene sequence similarity with Streptomyces rochei NRRL B-2410 T (99.0%) and Streptomyces naganishii NRRL ISP-5282 T (99.0%). Strain W18L9T shares high 16S rRNA gene sequence similarity with Streptomyces shenzhenensis DSM 42034 T (99.7%). The genotypic and phenotypic properties of strains SBTS01T and W18L9T distinguish these two strains from the closely related species with validly published names. The genome analysis showed the dDDH, ANIb and ANIm values of the draft genome between strain SBTS01T and its close neighbour in the phylogenomic tree, Streptomyces corchorusii DSM 40340T to be 54.1, 92.6, and 94.3%, respectively; similarly for strain W18L9T and the closely related species S. shenzhenensis DSM 42034 T values were 72.5, 95.1 and 97.0%. The name proposed for the new species represented by the type strain SBTS01T is Streptomyces spinosus (= NRRL B-65636 T = TBRC 15052T). The name proposed for the novel subspecies of strain W18L9T is Streptomyces shenzhenensis subsp. oryzicola (= NRRL B-65635 T = TBRC 15051T). Recognition of this subspecies also permits the description of Streptomyces shenzhenensis subsp. shenzhenensis. Strains SBTS01T and W18L9T can produce antibiotic against rice and human pathogens and showed plant growth promoting properties such as production of indole acetic acid, cytokinin, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, siderophores and cellulase. Genomic data mining of these two strains confirmed their potential as antibiotic producers and plant growth promoters. Their genomes contain multiple biosynthetic gene clusters including those for terpene, type 1, 2 and 3 polyketide synthase, Non-ribosomal peptide synthetase and lanthipeptides. Genes encoding plant growth promoting traits such; nitrogen fixation, ACC deaminase, siderophore production and stress-related adaption may have ecological significance.

Streptomyces adelaidensis sp. nov., an actinobacterium isolated from the root of Callitris preissii with potential for plant growth-promoting properties.

An endophytic actinobacterium, strain CAP261T was isolated from the surface sterilized root of Callitris preissii (Australian native pine tree). As a result of a polyphasic taxonomy study, this strain was identified as a member of the genus Streptomyces. This strain was an aerobic actinobacterium with well-developed substrate mycelia with loop spore chains and the spore surfaces are verrucose. The closest phylogenetic members which shared the highest 16S rRNA gene sequences similarity was Streptomyces bottropensis ATCC 25435 T at 98.1%. Chemotaxonomic data including cell wall components, major menaquinones, and major fatty acids confirmed the affiliation of strain CAP261T to the genus Streptomyces. The results of the phylogenetic analysis, including physiological and biochemical studies in combination with genome comparison study, allowed the genotypic and phenotypic differentiation of strain CAP261T and the closest species with validly published names. ANIb, ANIm and dDDH values of strain CAP261T and S. bottropensis ATCC 25435 T were 86.7%, 89.2% and 33.9%, respectively. The name proposed for the new species is Streptomyces adelaidensis sp. nov. The type strain is CAP261T (= DSM 42026 T = NRRL B-24814 T).

Pseudonocardia pini sp. nov., an endophytic actinobacterium isolated from roots of the pine tree Callitris preissii.

A Gram-positive, aerobic, actinobacterial strain with rod-shaped spores, CAP47RT, which was isolated from the surface-sterilized root of a native pine tree (Callitris preissii), grown in South Australia is described. The major cellular fatty acid of this strain was iso-H-C16:1 and major menaquinone was MK-8(H4). The diagnostic diamino acid in the cell-wall peptidoglycan was identified as meso-diaminopimelic acid. These chemotaxonomic data confirmed the affiliation of strain CAP47RT to the genus Pseudonocardia. Phylogenetic evaluation based on 16S rRNA gene sequence analysis placed this strain in the family Pseudonocardiaceae, being most closely related to Pseudonocardia xishanensis JCM 17906T (98.8%), Pseudonocardia oroxyli DSM 44984T (98.7%), Pseudonocardia thailandensis CMU-NKS-70T (98.7%), and Pseudonocardia ailaonensis DSM 44979T (97.9%). The results of the polyphasic study which contain genome comparisons of ANIb, ANIm, and digital DNA-DNA hybridization revealed the differentiation of strain CAP47RT from the closest species with validated names. This strain represents a novel species and the name proposed for this microorganism is Pseudonocardia pini sp. nov., indicating the source of this actinobacterium from a pine tree. The type strain is CAP47RT (= DSM 108967T = NRRL B-65534T). Genome mining revealed that this strain contained a variety of genes encoding enzymes that can degrade hazardous chemicals.

Genome mining and description of Streptomyces albidus sp. nov., an endophytic actinobacterium with antibacterial potential.

An endophytic actinobacterium, strain CAP215T was isolated from the root sample of a native pine tree (Callitris preissii), Adelaide, South Australia. This strain was a Gram stain-positive, aerobic actinobacterium with well-developed substrate mycelia. It produced spiral chains of spores. The closest phylogenetic members which shared the highest 16S rRNA gene sequence similarity were Streptomyces marinus DSM 41968T, Streptomyces haliclonae DSM 41970T and Streptomyces karpasiensis K413T at 98.2%, 98.0% and 97.9%, respectively. The major cellular fatty acid of this strain was anteiso-C15:0 and major menaquinone was MK-9(H4). Polar lipids of strain CAP215T contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol dimannoside and two unknown glycolipids. Chemotaxonomic data confirmed strain CAP215T belonged to the genus Streptomyces. Genome of strain CAP215T was 6.65 Mb with 69.8% DNA G + C content and contains 5992 coding sequences (CDS). Biosynthesis Genes Clusters (BGCs) comprised post-translationally modified peptides (RiPPs) cluster, genes encoding enzyme relating to antibiotic production; actinorhodin, surfactin and tetracenomycin. Genome mining of this strain identified genes encoding proteins relating to plant growth promotion such as pyrophosphatase, ectoine synthase, superoxide dismutase and siderophore production; penibactin and desferrioxamine E. Genes encoding beneficial enzymes; amylase, ß-xylosidase, chitinase, lipase and protease were detected. The genome of this strain contained genes encoding enzymes degrading xenobiotic compounds such as 2,4-dichlorophenol 6-monooxygenase, nitroreductase and epoxide hydrolase. Also, genes encoding squalene, hopene and betacarotenoid production were observed. Digital DNA-DNA (dDDH) hybridization, Average Nucleotide Identity BLAST (ANIb), ANI-MUMmer (ANIm) between strain CAP215T and S. marinus DSM 41968T were 25.4 %, 82% and 86.4%, respectively. The data on the genotypic and phenotypic characteristics and genome analysis recognized the differentiation of strain CAP215T with the closest species with valid names. The name Streptomyces albidus sp. nov. was proposed for which the type strain is CAP215T (= DSM 42025T = NRRL B-24815T).

Micromonospora veneta sp. nov., an endophytic actinobacterium with potential for nitrogen fixation and for bioremediation.

Strain CAP181T, an endophytic actinobacterium, was isolated from a surface sterilized root sample of a native pine tree, Flinders University, Adelaide, South Australia. Chemotaxonomic data including cell wall components, major fatty acids, and major menaquinones confirmed the affiliation of strain CAP181T to the genus Micromonospora. This strain was Gram stain positive with well-developed substrate mycelia to form a single spore with hairy surface. The phylogenetic tree showed that M. coerulea NBRC 13504 T is the closest phylogenetic neighbour, sharing 99.2% 16S rRNA gene similarity and the next closest neighbor is M. chaiyaphumensis DSM 45246 T (98.7%). Genome mining of this strain revealed genes encoding to enzymes relating to nitrogen fixation and bioremediation. Based on genotypic and phenotypic studies including DNA-DNA hybridization data, strain CAP181T was different from any of the closely related species with valid names. The name proposed for the new species is Micromonospora veneta sp. nov. The type strain is CAP181T (= DSM 109713 T = NRRL B-65535 T).

Amycolatopsis pittospori sp. nov., an endophytic actinobacterium isolated from native apricot tree and genome mining revealed the biosynthesis potential as antibiotic producer and plant growth promoter.

An endophytic actinobacterium, strain PIP199T, was isolated from a root sample of a native apricot growing on the Bedford Park campus of Flinders University, Adelaide, South Australia. The result of a polyphasic study showed that this strain was identified as a new member of the genus Amycolatopsis. Strain PIP199T is an aerobic actinobacterium with well-developed substrate mycelia and aerial mycelia that form short chains of spores. Amycolatopsis keratiniphila subsp. keratiniphila DSM 44409T (99.7%), Amycolatopsis lurida DSM 43134T (99.6%) and Amycolatopsis keratiniphila subsp. nogabecina DSM 44586T (99.4%) shared the highest 16S rRNA gene sequence similarity. A. keratiniphila subsp. keratiniphila DSM 44409T and A. lurida DSM 43134T were the closest phylogenetic neighbors. Chemotaxonomic data including major fatty acids, cell wall components and major menaquinones confirmed the affiliation of strain PIP199T to the genus Amycolatopsis. The phylogenetic analysis, physiological and biochemical studies and genomic study, allowed the genotypic and phenotypic differentiation of strain PIP199T and the closely related species with valid names. ANIb and dDDH values when compared to Amycolatopsis keratiniphila subsp. keratiniphila DSM 44409T were 87.3% and 36.4%, respectively. The name proposed for the new species is Amycolatopsis pittospori sp. nov. The type strain is PIP199T (= NRRL B-65536T = TBRC 10618T).

Microbispora clausenae sp. nov., an endophytic actinobacterium isolated from the surface-sterilized stem of a Thai medicinal plant, Clausena excavala Burm. f.

An endophytic actinobacterium, strain CLES2T, was discovered from the surface-sterilized stem of a Thai medicinal plant, Clausena excavala Burm. f., collected from the Phujong-Nayoa National Park, Ubon Ratchathani Province, Thailand. The results of a polyphasic taxonomic study identified this strain as a member of the genus Microbispora and a Gram-stain-positive, aerobic actinobacterium. It had well-developed substrate mycelia, which were non-motile and possessed paired spores. A phylogenetic evaluation based on 16S rRNA gene sequence analysis placed this strain in the family Streptosporangiaceae, being most closely related to Microbispora bryophytorum NEAU-TX2-2T (99.4 %), Microbispora camponoti 2C-HV3T (99.2 %), Microbispora catharanthi CR1-09T (99.2 %) and Microbispora amethystogenes JCM 3021T and Microbispora fusca NEAU-HEGS1-5T (both at 99.1 %). The major cellular fatty acid of this strain was iso-C16 : 0 and major menaquinone was MK-9(H4). The polar lipid profile of strain CLES2T contained diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylinositol and phosphatidylinositol dimannosides. These chemotaxonomic data confirmed the affiliation of strain CLES2T to the genus Microbispora. The DNA G+C content of this strain was 70 mol%. Digital DNA-DNA hybridization and average nucleotide identity blast values between strain CLES2T and M. catharanthi CR1-09T were 62.4 and 94.0 %, respectively. The results of the polyphasic study allowed the genotypic and phenotypic differentiation of strain CLES2T from its closest species with valid names. The name proposed for the new species is Microbispora clausenae sp. nov. The type strain is CLES2T (=DSM 101759T=NRRL B-65340T).

Actinomycetospora callitridis sp. nov., an endophytic actinobacterium isolated from the surface-sterilised root of an Australian native pine tree.

An endophytic actinobacterium, strain CAP 335T, was isolated from a root sample of a native pine tree growing on the Bedford Park campus of Flinders University, Adelaide, South Australia. The result of a polyphasic study showed that this strain was identified as a new member of the genus Actinomycetospora. This strain was observed to be a Gram stain-positive, aerobic actinobacterium with well-developed substrate mycelia and to form short chains of spores. Actinomycetospora chibensis TT04-21T and Actinomycetospora straminea IY07-55T were found to be close phylogenetic neighbours, each sharing 99.1% 16S rRNA gene similarity. Chemotaxonomic data including major fatty acids, cell wall components and major menaquinones confirmed the affiliation of strain CAP 335T to the genus Actinomycetospora. The phylogenetic analysis, physiological and biochemical studies and DNA-DNA hybridization, allowed the genotypic and phenotypic differentiation of strain CAP 335T and the closely related species with valid names. The name proposed for the new species is Actinomycetospora callitridis sp. nov. The type strain is CAP 335T (= DSM 101857T = NRRL B-65350T).

Streptomyces roietensis sp. nov., an endophytic actinobacterium isolated from the surface-sterilized stem of jasmine rice, Oryza sativa KDML 105.

An endophytic actinobacterium, strain WES2T, was isolated from the stem of a jasmine rice plant collected from a paddy field in Thung Gura Rong Hai, Roi Et province, Thailand. As a result of a polyphasic study, this strain was identified as representing a novel member of the genus Streptomyces. This strain was a Gram-stain-positive, aerobic actinobacterium with well-developed substrate mycelia and forming chains of looped spores. The closest phylogenetic relations, which shared the highest 16S rRNA gene sequence similarity, were Streptomyces nogalater JCM 4799T and Streptomyces lavenduligriseus NRRL-ISP 5487T at 99.1 and 99.0 %, respectively. Chemotaxonomic data, including major fatty acids, cell wall components and major menaquinones, confirmed the affiliation of WES2T to the genus Streptomyces. The data from the phylogenetic analysis, including physiological and biochemical studies and DNA-DNA hybridization, revealed the genotypic and phenotypic differentiation of WES2T from the most closely related species with validly published names. The name proposed for the novel species is Streptomycesroietensis sp. nov. The type strain is WES2T (=DSM 101729=NRRL B-65344).

Promicromonospora callitridis sp. nov., an endophytic actinobacterium isolated from the surface-sterilized root of an Australian native pine tree.

A new strain of the genus Promicromonospora, CAP94T, was isolated from the surface sterilized root of Callitrispreissii (Australian native pine tree). This strain was a Gram-stain-positive, aerobic actinobacterium with hyphae breaking up into fragments which were non-motile, rod-like, coccoid elements. Phylogenetic evaluation based on 16S rRNA gene sequence analysis placed this isolate as a member of the family Promicromonospora ceae, and most closely to Promicromonospora sukumoe NBRC 14650T (99.4 %), Promicromonospora kroppenstedtii DSM 19349T (99.2 %) and Promicromonosporaaerolata V54AT (99.1 %). Chemotaxonomic data including cell-wall components, major menaquinone and major fatty acids confirmed the affiliation of strain CAP94T to the genus Promicromonospora. The results of the phylogenetic analysis, including physiological and biochemical studies in combination with DNA-DNA hybridization, allowed the genotypic and phenotypic differentiation of strain CAP94T and the closest species with validly published names. The name proposed for the new species is Promicromonospora callitridis sp. nov. The type strain is CAP94T (=DSM 103339T=TBRC 6025T).

Micromonospora terminaliae sp. nov., an endophytic actinobacterium isolated from the surface-sterilized stem of the medicinal plant Terminalia mucronata.

An endophytic actinobacterium, strain TMS7T, was isolated from the stem of a Thai medicinal plant collected from the grounds of the Phujong-Nayoa National park, Ubon Ratchathani province, Thailand. As a result of a polyphasic taxonomy study, this strain was identified as a member of the genus Micromonospora. This strain was a Gram-stain-positive, aerobic actinobacterium with well-developed substrate mycelium with hyphae forming a single microspore was non-motile. Stran TMS7T was identified according to its 16S rRNA gene sequence as a new member of the genus Micromonospora. The closest phylogenetic members sharing a similarity were Micromonospora chersina DSM 44151T at 99.4 % and Micromonospora rosaria DSM 803T, Micromonospora tulbaghiae TVU1T, Micromonospora inositola DSM 43819T and Micromonospora endolithica DSM 44398T all at 99.2 %. Chemotaxonomic data including cell wall components, major menaquinones and major fatty acids confirmed the affiliation of strain TMS7T to the genus Micromonospora. The results of the phylogenetic analysis, addition to physiological and biochemical studies in combination with DNA-DNA hybridization, allowed the genotypic and phenotypic differentiation of strain TMS7T and the most closely related species with validly published names. The name proposed for the novel species is Micromonospora terminaliae sp. nov. The type strain is TMS7T (=DSM 101760T=NRRL B-65345T).

Kribbella pittospori sp. nov., an endophytic actinobacterium isolated from the surface-sterilized stem of an Australian native apricot tree, Pittosporum angustifolium.

An endophytic actinobacterium, strain PIP 158T, was isolated from the stem of a native apricot tree (Pittosporum angustifolium) collected from the grounds of Flinders University, Adelaide, Australia. As a result of a polyphasic taxonomic study, this strain was identified as a member of the genus Kribbella. This strain was a Gram-stain-positive, aerobic actinobacterium with well-developed substrate mycelia which were non-motile and with hyphae fragmenting into short to elongated rod-like elements. Phylogenetic evaluation based on 16S rRNA gene sequence analysis placed this isolate in the family Nocardioidaceae, being most closely related to Kribbella sandramycini ATCC 39419T and Kribbella albertanoniae BC640T which share a similarity of 99. 26 and 99.18 % with Kribbella hippodromi S1.4T, respectively. Chemotaxonomic data including cell-wall components, major menaquinones and major fatty acids confirmed the affiliation of strain PIP 158T to the genus Kribbella. The results of the phylogenetic analysis, including physiological and biochemical studies in combination with DNA-DNA hybridization, allowed the genotypic and phenotypic differentiation of strain PIP 158T from the closest related species with validly published names. The name proposed for the novel species is Kribbella pittospori sp. nov. The type strain is PIP 158T (=DSM 23717T=NRRL B-24813T).

Rational approaches to improving the isolation of endophytic actinobacteria from Australian native trees.

In recent years, new actinobacterial species have been isolated as endophytes of plants and shrubs and are sought after both for their role as potential producers of new drug candidates for the pharmaceutical industry and as biocontrol inoculants for sustainable agriculture. Molecular-based approaches to the study of microbial ecology generally reveal a broader microbial diversity than can be obtained by cultivation methods. This study aimed to improve the success of isolating individual members of the actinobacterial population as pure cultures as well as improving the ability to characterise the large numbers obtained in pure culture. To achieve this objective, our study successfully employed rational and holistic approaches including the use of isolation media with low concentrations of nutrients normally available to the microorganism in the plant, plating larger quantities of plant sample, incubating isolation plates for up to 16 weeks, excising colonies when they are visible and choosing Australian endemic trees as the source of the actinobacteria. A hierarchy of polyphasic methods based on culture morphology, amplified 16S rRNA gene restriction analysis and limited sequencing was used to classify all 576 actinobacterial isolates from leaf, stem and root samples of two eucalypts: a Grey Box and Red Gum, a native apricot tree and a native pine tree. The classification revealed that, in addition to 413 Streptomyces spp., isolates belonged to 16 other actinobacterial genera: Actinomadura (two strains), Actinomycetospora (six), Actinopolymorpha (two), Amycolatopsis (six), Gordonia (one), Kribbella (25), Micromonospora (six), Nocardia (ten), Nocardioides (11), Nocardiopsis (one), Nonomuraea (one), Polymorphospora (two), Promicromonospora (51), Pseudonocardia (36), Williamsia (two) and a novel genus Flindersiella (one). In order to prove novelty, 12 strains were characterised fully to the species level based on polyphasic taxonomy. One strain represented a novel genus in the family Nocardioides, and the other 11 strains were accepted as novel species. In summary, the holistic isolation strategies were successful in obtaining significant culturable actinobacterial diversity within Australian native trees that includes rare and novel species.

Kribbella endophytica sp. nov., an endophytic actinobacterium isolated from the surface-sterilized leaf of a native apricot tree.

A new strain of the genus Kribbella, PIP 118(T), was isolated from the leaf of an Australian native apricot tree (Pittosporum angustifolium), or Gumbi Gumbi in the indigenous language. This strain is an aerobic actinobacterium consisting of hyphae that fragment into short to elongated rod-like elements. Phylogenetic evaluation based on 16S rRNA gene sequence analysis placed this isolate as a member of the family Nocardioidaceae and most closely related to Kribbella antibiotica YIM 31530(T) (98.6 %) and Kribbella koreensis LM 161(T) (98.4 %). Chemotaxonomic data including cell wall components, major menaquinone and major fatty acids confirmed the affiliation of strain PIP 118(T) to the genus Kribbella. The results of the phylogenetic analysis, including physiological and biochemical studies in combination with DNA-DNA hybridization, allowed the genotypic and phenotypic differentiation of strain PIP 118(T) and members of the most closely related species with validly published names. The name proposed for the new species is Kribbella endophytica sp. nov. The type strain is PIP 118(T) ( = DSM 23718(T) = NRRL B-24812(T)).