New secondary metabolites from an engineering mutant of endophytic Streptomyces sp. CS.

In previous work, a series of bioactive natural products had been isolated from the plant endophytic Streptomyces sp. CS, which was isolated from Maytenus hookeri. To mine new active metabolites, we describe introducing an alien carbamoyltransferase (asm21) gene into the strain CS by conjugal transfer. As a result, three recombinatorial mutants named CS/asm21-1, CS/asm21-2 and CS/asm21-4 were successfully constructed. Three mutants and wild type CS were cultured on solid medium, and the extracts were detected and analyzed by liquid chromatography-mass spectrometry (LC-MS). The LC-MS profiles showed several unknown peaks that were present in the spectra of extracts of the CS/asm21-4 cultured on oatmeal solid medium. Then, three new naphthomycins O-Q (1-3), a new macrolide hookerolide (4) as well as nine known compounds were obtained from the solid cultured medium. Their structures were identified by spectra data. These new compounds showed moderate antimicrobial activities.

Spatial-temporal profiling of prodiginines and serratamolides produced by endophytic Serratia marcescens harbored in Maytenus serrata.

An endophytic bacterium, Serratia marcescens MSRBB2, isolated from inner bark of a Cameroonian Maytenus serrata plant, was subjected to the OSMAC (One Strain Many Compounds) approach and metabolic profiling using HPLC-HRMSn. We identified 7 prodiginines along with 26 serratamolides. Their biosynthetic pathways were elucidated by feeding with labeled precursors in combination with HRMSn. Dual-culture confrontation/restriction assays of the bacterial endophyte were devised with coexisting fungal endophytes (Pestalotiopsis virgatula, Aspergillus caesiellus and Pichia spp.) as well as with unrelated, non-endophytic fungi belonging to the same genera. The assays were combined with scanning electron microscopy (SEM) as well as matrix-assisted laser desorption ionization imaging high-resolution mass spectrometry (MALDI-imaging-HRMS) for visualizing, both in high spatial and temporal resolution, the distribution and interplay of the compounds during microbial interactions. We demonstrated the effect of prodigiosin produced by endophytic S. marcescens MSRBB2 as an allelochemical that specifically inhibits coexisting endophytic fungi. Our results provide new insights into the physiological and ecological relevance of prodiginines and serratamolides within the context of allelopathy and chemical defense interaction occurring between coexisting endophytes harbored in M. serrata.

Genome sequence and comparative analysis of Jiangella alba YIM 61503T isolated from a medicinal plant Maytenus austroyunnanensis.

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.

Plant-plant competition outcomes are modulated by plant effects on the soil bacterial community.

Competition is a key process that determines plant community structure and dynamics, often mediated by nutrients and water availability. However, the role of soil microorganisms on plant competition, and the links between above- and belowground processes, are not well understood. Here we show that the effects of interspecific plant competition on plant performance are mediated by feedbacks between plants and soil bacterial communities. Each plant species selects a singular community of soil microorganisms in its rhizosphere with a specific species composition, abundance and activity. When two plant species interact, the resulting soil bacterial community matches that of the most competitive plant species, suggesting strong competitive interactions between soil bacterial communities as well. We propose a novel mechanism by which changes in belowground bacterial communities promoted by the most competitive plant species influence plant performance and competition outcome. These findings emphasise the strong links between plant and soil communities, paving the way to a better understanding of plant community dynamics and the effects of soil bacterial communities on ecosystem functioning and services.

Antimicrobial metabolites from endophytic Streptomyces sp. YIM61470.

Six compounds were isolated from Streptomyces sp. YIM61470, and their structures elucidated by spectral analysis as (R)-1-O-(phenylacetyl)glycerol (1), 4',5-dihydroxy-6-(3,3-dimethylallyl)-7-methoxyflavanone (2), (32R,33R,34S) -32,33,34,35-bacteriohopanetetrol (3), MKN-003C (4), cyclo (L-Pro-L-Gly) (5), and cyclo(L-Pro-L-Tyr) (6). Compound 1, an chiral monoacylglycerol, was isolated from a natural source for the first time. Compound 2 was first found in microorganisms, and compound 3, a bacteriohopanoid, was found first in the genus Streptomyces. Compounds 1-6 showed weak anti-microbial activity.

Promicromonospora xylanilytica sp. nov., an endophytic actinomycete isolated from surface-sterilized leaves of the medicinal plant Maytenus austroyunnanensis.

A novel xylan-degrading actinomycete, strain YIM 61515(T), was isolated from surface-sterilized leaves of the medicinal plant Maytenus austroyunnanensis. Cells were Gram-positive and non-spore-forming, produced primary branches and formed white to yellowish white colonies on the media tested. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM 61515(T) was most similar to Promicromonospora aerolata V54A(T) and Promicromonospora vindobonensis V45(T) (99.4 and 99.1% sequence similarity, respectively). The isolate formed a separate lineage in a cluster containing P. aerolata V54A(T). 16S rRNA gene sequence similarity between the isolate and other members of the genus Promicromonospora ranged from 96.3 to 98.4%. Chemotaxonomic data, including major menaquinones, fatty acid compositions and polar lipid profiles, supported the placement of strain YIM 61515(T) in the genus Promicromonospora. DNA-DNA relatedness, physiological and biochemical data showed that strain YIM 61515(T) could be distinguished from members of all known species of the genus Promicromonospora and therefore represented a novel species. The name Promicromonospora xylanilytica sp. nov. is proposed, with YIM 61515(T) (=DSM 21603(T)=CCTCC AA 208046(T)) as type strain.

Pseudonocardia tropica sp. nov., an endophytic actinomycete isolated from the stem of Maytenus austroyunnanensis.

A novel strain, designated YIM 61452(T), was isolated from the stem of Maytenus austroyunnanensis collected from the tropical rainforest of Xishuangbanna, Yunnan Province, south-west China. The strain was characterized taxonomically by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM 61452(T) belonged to the genus Pseudonocardia and was most closely related to Pseudonocardia alni IMSNU 20049(T) (99.5 %), Pseudonocardia antarctica DVS 5a1(T) (99.5 %) and Pseudonocardia carboxydivorans Y8(T) (99.4 %). The chemotaxonomic properties of strain YIM 61452(T), for example MK-8(H(4)) as the predominant quinone system and iso-C(16 : 0) and iso-C(16 : 1) H as the major fatty acids, were also consistent with its classification within the genus Pseudonocardia. Strain YIM 61452(T) could be differentiated from closely related species of the genus Pseudonocardia by phenotypic and genotypic analysis. DNA-DNA hybridization experiments between strain YIM 61452(T) and closely related reference strains further confirmed that strain YIM 61452(T) represented a novel taxon of the genus Pseudonocardia. Therefore, strain YIM 61452(T) represents a novel species, for which the name Pseudonocardia tropica sp. nov. is proposed. The type strain is YIM 61452(T) (=DSM 45199(T)=CCTCC AA 208018(T)).

Endophytic fungus Trichothecium roseum LZ93 antagonizing pathogenic fungi in vitro and its secondary metabolites.

The endophytic fungus Trichothecium roseum LZ93 from Maytenus hookeri was found to antagonize other pathogenic fungi in vitro. To identify which compound contributed substantially to the antagonism, we fermented the strain and purified its fermentation products. Eleven compounds were obtained, including two trichothecenes, five rosenonolactones, two cardiotonic cyclodepsipeptides, and two sterols. Compound 11ß-hydroxyrosenonolactone (1) was assigned according to 1D and 2D-NMR data for the first time. At the same time, the (1)H and (13)C-NMR assignments for 6ß-hydroxyrosenonolactone (2) were revised. Of all of them, only trichothecin (6) showed strong antifungal activity. Based on our observations of the antagonistic activity and the other experimental results, we suggest that the antifungal compound trichothecin was the main contributor to the antagonistic action of T. roseum LZ93.

Molecular and morphological markers for rapid distinction between 2 Colletotrichum species.

Endophytic microorganisms reside asymptomatically within plants and are a source of new bioactive products for use in medicine, agriculture, and industry. Colletotrichum (teleomorph Glomerella) is a fungus widely cited in the literature as a producer of antimicrobial substances. Identification at the species level, however, has been a problem in this type of study. Several authors have reported the presence of endophytic fungi from the medicinal plant Maytenus ilicifolia ("espinheira-santa") in Brazil that has antimicrobial activity against various pathogens. Therefore, Colletotrichum strains were isolated from M. ilicifolia and identified based on morphology, RAPD markers, sequence data of the internal transcribed spacer regions (ITS-1 and ITS-2), the 5.8S gene, and species-specific PCR. The analyses suggested the presence of 2 species, Colletotrichum gloeosporioides and Colletotrichum boninense. Two morphological markers were characterized to allow C. gloeosporioides and C. boninense to be distinguished quickly and accurately. The molecular diagnosis of C. boninense was confirmed by using Col1 and ITS4 primers. This species of Colletotrichum is reported for the first time in M. ilicifolia.

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)).

Actinomadura flavalba sp. nov., an endophytic actinomycete isolated from leaves of Maytenus austroyunnanensis.

An actinomycete strain, designated YIM 61435(T), was isolated from leaves of Maytenus austroyunnanensis collected from a tropical rainforest in Xishuangbanna, Yunnan Province, south-west China. The isolate produced aerial mycelium with long, curved to hooked spore chains. The chemotaxonomic characteristics of the isolate were consistent with its assignment to the genus Actinomadura. Phylogenetic analysis using 16S rRNA gene sequences also indicated that this strain should be classified in the genus Actinomadura; however, it could be separated clearly from its closest neighbour, Actinomadura atramentaria DSM 43919(T). Furthermore, a combination of DNA-DNA hybridization results and significant differences in morphological and physiological characteristics indicate that strain YIM 61435(T) represents a novel species of the genus Actinomadura, for which the name Actinomadura flavalba sp. nov. is proposed. The type strain is YIM 61435(T) (=DSM 45200(T) =CCTCC AA 208017(T)).

Jiangella alba sp. nov., an endophytic actinomycete isolated from the stem of Maytenus austroyunnanensis.

A novel actinomycete strain, YIM 61503T, isolated from the stem of Maytenus austroyunnanensis, was characterized by using a polyphasic approach. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain YIM 61503T belonged to the genus Jiangella and exhibited 16S rRNA gene sequence similarities of 98.8 and 98.6% to Jiangella alkaliphila D8-87T and Jiangella gansuensis YIM 002T. The chemotaxonomic properties of strain YIM 61503T were consistent with those of the genus Jiangella: the cell-wall peptidoglycan type was based on ll-diaminopimelic acid and MK-9(H4) was the predominant menaquinone. The major fatty acids were anteiso-C15:0, iso-C16:0, iso-C14:0, C17:1omega8c and anteiso-C17:0. The DNA G+C content was 71.9 mol%. Strain YIM 61503T was phenotypically distinct from recognized Jiangella species and was shown to belong to a separate genomic species based on DNA-DNA hybridization results. Thus, strain YIM 61503T is considered to represent a novel species of the genus Jiangella, for which the name Jiangella alba sp. nov. is proposed. The type strain is YIM 61503T (=DSM 45237T=CCTCC AA 208023T).

Actinopolymorpha alba sp. nov., isolated from a rhizosphere soil.

A Gram-positive, milk-white coloured, aerobic strain, YIM 48868T, was isolated from the rhizosphere soil of Maytenus hookeri Loes in Xishuangbanna, China. 16S rRNA gene sequence similarity studies showed that strain YIM 48868T was a member of the genus Actinopolymorpha, showing 96.8% sequence similarity to Actinopolymorpha singaporensis IM 7744T and 97.0% similarity to Actinopolymorpha rutila YIM 45725T. Chemotaxonomic data (peptidoglycan type I, ll-diaminopimelic acid; sugar pattern C, glucose, rhamnose and ribose; polar lipids PI, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannosides and phosphatidylinositol) were characteristic of the genus Actinopolymorpha. A phylogenetic tree based on 16S rRNA gene sequences showed that strain YIM 48868T formed a distinct phylogenetic lineage within the genus Actinopolymorpha. Strain YIM 48868T could be differentiated from recognized species by means of phenotypic properties and the predominant menaquinones [MK-9(H6), MK-9(H8), MK-10(H6), MK-10(H8)]. The DNA G+C content was 66.6 mol%. The DNA-DNA relatedness values between strain YIM 48868T and the type strains of A. singaporensis and A. rutila were 48.7% and 53.1%, respectively. These data, in combination with phenotypic and chemotaxonomic data, demonstrate that strain YIM 48868T represents a novel species in the genus Actinopolymorpha, for which the name Actinopolymorpha alba sp. nov. is proposed. The type strain is YIM 48868T (=CCTCC AA 208030T=DSM 45243T).

Nonomuraea antimicrobica sp. nov., an endophytic actinomycete isolated from a leaf of Maytenus austroyunnanensis.

A novel actinomycete strain, designated YIM 61105(T), was isolated from a leaf of Maytenus austroyunnanensis from the tropical rainforest in Xishuangbanna, Yunnan Province, south-west China. A 16S rRNA gene sequence analysis revealed that the organism belonged to the phylogenetic cluster of the genus Nonomuraea and was most closely related to Nonomuraea candida HMC10(T) (98.2 %), 'Nonomuraea aegyptia' S136 (97.9 %), Nonomuraea kuesteri GW 14-1925(T) (97.5 %) and Nonomuraea turkmeniaca DSM 43926(T) (97.4 %). The 16S rRNA gene sequence similarities to other Nonomuraea species were less than 97.4 %. The main chemotaxonomic properties of strain YIM 61105(T), such as the principal amino acid of the peptidoglycan, the predominant menaquinone and the polar lipid profile, supported its classification within the genus Nonomuraea. Strain YIM 61105(T) was also readily differentiated from closely related species on the basis of a broad range of phenotypic properties and DNA-DNA hybridization values. Thus, this isolate is considered to represent a novel species of the genus Nonomuraea, for which the name Nonomuraea antimicrobica sp. nov. is proposed. The type strain is YIM 61105(T) (=DSM 45220(T)=CCTCC AA 208016(T)).

Glycomyces scopariae sp. nov. and Glycomyces mayteni sp. nov., isolated from medicinal plants in China.

Two actinomycete strains, designated YIM 56256(T) and YIM 61331(T), were isolated from the roots of Scoparia dulcis and Maytenus austroyunnanensis, two Chinese medicinal plants, and their taxonomic status was established based on a polyphasic investigation. The organisms were found to have chemical and morphological markers typical of members of the genus Glycomyces. 16S rRNA gene sequence analysis showed that they were closely related to each other and to Glycomyces sambucus E71(T). A battery of physiological characteristics and levels of DNA-DNA relatedness indicated that strains YIM 56256(T) and YIM 61331(T) represent two novel species, clearly different from the related known Glycomyces species. On the basis of the data presented, it is evident that each of these strains represents a novel species of the genus Glycomyces, for which the names Glycomyces scopariae sp. nov. (type strain YIM 56256(T) =KCTC 19158(T) =DSM 44968(T)) and Glycomyces mayteni sp. nov. (type strain YIM 61331(T) =KCTC 19527(T) =CCTCC AA 208004(T)) are proposed.

Streptomyces mayteni sp. nov., a novel actinomycete isolated from a Chinese medicinal plant.

An actinomycete strain, designated YIM 60475(T), was isolated from the roots of Maytenus austroyunnanensis and was characterized by using a polyphasic approach. The strain was determined to belong to the genus Streptomyces, based on its phenotypic and phylogenetic characteristics. The strain produced spiral spore chains on aerial mycelium. The cell wall contained LL-diaminopimelic acid. Whole-cell hydrolysates contained galactose, glucose, and xylose. The phospholipid was type II. The DNA G+C content of the type strain was 73.3 mol%. DNA-DNA hybridization and comparison of physiological and chemical characteristics suggested that strain YIM 60475(T) is a new Streptomyces species, for which the name Streptomyces mayteni sp. nov. is proposed. The type strain is YIM 60475(T) (=CCTCC AA 207005(T) = KCTC 19383(T)).

Saccharopolyspora endophytica sp. nov., an endophytic actinomycete isolated from the root of Maytenus austroyunnanensis.

A Gram-positive, aerobic, non-motile, non-acid-alcohol-fast strain, designated YIM 61095(T), was isolated from the root of Maytenus austroyunnanensis collected from a tropical rainforest of Xishuangbanna in Yunnan Province, south-west China. Strain YIM 61095(T) exhibited chemotaxonomic and morphological characteristics that were consistent with members of the genus Saccharopolyspora. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM 61095(T) was a member of the genus Saccharopolyspora and was most closely related to Saccharopolyspora flava AS 4.1520(T) (97.7% sequence similarity). The major fatty acids were iso-C(15:0), iso-C(16:0), iso-C(17:0) and anteiso-C(17:0). The predominant quinone detected was MK-9(H(4)). The DNA G+C content was 66.2 mol%. The phenotypic characteristics and DNA-DNA hybridization relatedness data indicated that strain YIM 61095(T) should be distinguished from Saccharopolyspora flava AS 4.1520(T). On the basis of the evidence presented in this study, strain YIM 61095(T) represents a novel species of the genus Saccharopolyspora, for which the name Saccharopolyspora endophytica sp. nov. is proposed. The type strain is YIM 61095(T) (=KCTC 19397(T)=CCTCC AA 208003(T)).

Bioprospecting highly diverse endophytic Pestalotiopsis spp. with antibacterial properties from Maytenus ilicifolia, a medicinal plant from Brazil.

Thirteen endophytic fungal strains of the genus Pestalotiopsis were isolated from the medicinal plant Maytenus ilicifolia Mart. ex. Reiss (commonly known as "espinheira santa") and their antimicrobial properties were investigated. Two isolates were successful in inhibiting the growth of the tested microorganisms (Escherichia coli, Klebsiella pneumoniae, Micrococcus luteus, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA)) using the technique of bioautographic thin-layer chromatography (TLC) agar overlay assay. An analysis based on a polyphasic approach integrating taxonomic information, morphological traits, RAPD markers, and the sequencing of the ITS1-5.8S-ITS2 of the rDNA led to the assignment of the isolates as belonging to the species Pestalotiopsis microspora, Pestalotiopsis vismiae, and Pestalotiopsis leucothoes. Therefore, the present study presents a new approach to the study of endophytic fungi of the genus Pestalotiopsis.

Tricycloalternarene derivatives produced by an endophyte alternaria alternata isolated from Maytenus hookeri.

A new tricycloalternarene derivative, named tricycloalternarenal (1), together with three known compounds was isolated from the cultures of Alternaria alternata, an endophytic fungus in the leaves of the plant Maytenus hooker! (Celastraceae). Structure of 1 was established as (2E)-6-(3, 3a, 5, 6, 7, 8, 9, 9a-octahydro-5-hydroxy-3a-methyl-8-oxo-cyclo-penta[b]chromen-1-yl)-2-methylhept-2-enal by spectroscopic methods, including 2D-NMR experiments. The remaining compounds were determined as tricycloalternarene-3b (2), alterperylenol (3), and dihydroalterperylenol (4).

Secondary metabolites from endophytic Streptomyces sp. Lz531.

From the branch tissue of Maytenus hookeri, the endophytic strain Lz531 was isolated, and determined to belong to Streptomyces, according to its 16S rRNA sequence. From the extracts of the fermentation broth of Streptomyces sp. Lz531, two new and four known compounds were isolated. The two new compounds were identified as cyclo(L-Pro-L-Val-L-Val) (1) and 13-methyl-N-(2-phenylethyl)tetradecanamide (2).