Streptomyces xanthii sp. nov. and Streptomyces roseirectus sp. nov. isolated from a Chinese medicinal plant.

Two strains of Actinobacteria, designated CRXT-Y-14T and CRXT-G-22T, were isolated from the healthy leaves and seeds, respectively, of a medicinal plant Xanthium sibiricum. Their taxonomic positions were determined using a polyphasic approach. Strain CRXT-Y-14T produced flexuous chains of smooth-surfaced spores. Strain CRXT-G-22T produced straight chains of smooth-surfaced spores. Their morphological features were consistent with the diagnostic characteristics of members of the genus Streptomyces. The results of 16S rRNA gene sequence analyses indicated two strains represented members of the genus Streptomyces. CRXT-Y-14T shared 99.3, 98.9, 98.8 % sequence similarities to Streptomyces atriruber NRRL B-24165T, Streptomyces avermitilis MA-4680T and Streptomyces davaonensis JCM 4913T, respectively. Whilst CRXT-G-22T exhibited highest similarity to Streptomyces acidiscabies ATCC 49003T (98.9 %). The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the closest phylogenetic neighbours of strains CRXT-Y-14T and CRXT-G-22T were S. atriruber NRRL B-24165T and S. acidiscabies ATCC 49003T, respectively. The phylogenomic analyses further confirmed the relative relationship between strain CRXT-G-22T and S. acidiscabies ATCC 49003T, but indicated that CRXT-Y-14T could represent a novel species of the genus Streptomyce. However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between CRXT-Y-14T and strain CRXT-G-22T, between CRXT-Y-14T and S. atriruber NRRL B-24165T, and between CRXT-G-22T and S. acidiscabies ATCC 49003T were 85.4 and 23.2 %, 85.8 and 23.9 % and 89.1 and 34.1 %, respectively, far below the 95~96 and 70 % cut-off points recommended for delineating species. Furthermore, these two novel isolates were distinctly differentiated from their relatives in the genus Streptomyces with respect to phenotypic and chemotaxonomic characteristics. On the basis of these data, CRXT-Y-14T and CRXT-G-22T clearly represent two novel species within the genus Streptomyces, for which the names Streptomyces xanthii sp. nov. (type strain CRXT-Y-14T = MCCC 1K04966T= JCM 34527T) and Streptomyces roseirectus sp. nov. (type CRXT-G-22T = MCCC 1K04979T= JCM 34565T) are proposed.

Streptomyces genisteinicus sp. nov., a novel genistein-producing actinomycete isolated from a Chinese medicinal plant and proposal of Streptomyces michiganensis Corbaz et al. 1957 as a later heterotypic synonym of Streptomyces xanthochromogenes Arishima et al. 1956.

A novel genistein-producing actinobacterial strain, designated strain CRPJ-33T, was isolated from the healthy leaves of a medicinal plant Xanthium sibiricum collected from Hunan Province, PR China. 16S rRNA gene sequence analysis indicated strain CRPJ-33T belonged to the genus Streptomyces and had 99.7, 99.0, 98.9, 98.9, 98.8 and 98.7% sequence similarities to Streptomyces zhihengii YIM T102T, Streptomyces eurocidicus NRRL B-1676T, Streptomyces xanthochromogenes NRRL B-5410T, Streptomyces michiganensis NBRC 12797T, Streptomyces mauvecolor LMG 20100T and Streptomyces lavendofoliae NBRC 12882T, respectively. Phylogenetic analysis of 16S rRNA gene sequences showed that strain CRPJ-33T was most closely related to S. zhihengii YIM T102T. However, digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between them were much less than the recommended threshold values. Furthermore, differential comparisons of the phenotypic characteristics were enough to distinguish strain CRPJ-33T from S. zhihengii YIM T102T. Meanwhile, the ANI and dDDH values or MLSA distances between strain CRPJ-33T and other type strains, which exhibited ≥98.7 % 16S rRNA gene sequence similarities to strain CRPJ-33T, were far away from the recommended threshold values. Based on these results, it is thought that strain CRPJ-33T should represent a novel species of the genus Streptomyces, for which the name Streptomyces genisteinicus sp. nov. is proposed. The type strain is CRPJ-33T (=MCCC 1K04965T=JCM 34526T). In addition, the phenotypic, chemotaxonomic and genotypic characteristics, as well as phylogenetic information revealed that the type strains of S. xanthochromogenes and S. michiganensis should belong to same genomic species. Consequently, it is proposed that S. michiganensis is a heterotypic synonym of S. xanthochromogenes for which an emended description is given.

Two Phytotoxins Isolated from the Pathogenic Fungus of the Invasive Weed Xanthium italicum.

Alternariol and altenuisol were isolated as the major phytotoxins produced by an Alternaria sp. pathogenic fungus of the invasive weed Xanthium italicum. Altenuisol exhibited stronger phytotoxic effect compared with alternariol. At 10 µg/mL, alternariol and altenuisol promoted root growth of the monocot plant Pennisetum alopecuroides by 11.1 % and 75.2 %, respectively, however, inhibitory activity was triggered by the increase of concentration, with root elongation being suppressed by 35.5 % and 52.0 % with alternariol and altenuisol at 1000 µg/mL, respectively. Alternariol slightly inhibited root length of the dicot plant Medicago sativa at 10-1000 µg/mL, whereas altenuisol stimulated root growth by 51.0 % at 10 µg/mL and inhibited root length by 43.4 % at 200 µg/mL. Alternariol and altenuisol did not exert strong regulatory activity on another dicot plant, Amaranthus retroflexus, when tested concentration was low, however, when the concentration reached 1000 µg/mL, they reduced root length by 68.1 % and 51.0 %, respectively. Alternariol and altenuisol exerted similar effect on shoot growth of three tested plants but to a lesser extent. It is noteworthy to mention that this is the first report on the phytotoxicity of altenuisol.

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

The taxonomic position of a novel actinomycete isolate, designated strain GGCR-6T, isolated from the healthy leaves of Xanthium sibiricum collected from the botanic garden of Hunan University of Science and Technology in Hunan province, PR China, was determined by a polyphasic approach. GGCR-6T grew well on ISP series media and formed well-developed, branched substrate hyphae and aerial mycelium that differentiated into straight spore chains consisting of cylindrical spores with smooth surfaces. The diagnostic diamino acid was ll-diaminopimelic acid. The major menaquinones were MK-9(H8), MK-9(H2), MK-9 and MK-9(H6). The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphotidylinositol and phosphatidylinositol mannosides. The predominant fatty acids were C16 : 1ω9c, iso-C16 : 0 and C16 : 0. The phenotypic characteristics of GGCR-6T indicated that it represented a member of the genus Streptomyces. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that GGCR-6T was most closely related to Streptomyces cyaneus NRRL B2296T and Streptomyces griseoruber NRRL B1818T. However, the digital DNA-DNA hybridization, the average nucleotide identity and the multi locus sequence analysis evolutionary distance clearly separate GGCR-6T from the phylogenetically closely related species. Furthermore, the novel isolate was distinctly differentiated from S. cyaneus NRRL B2296T and S. griseoruber NRRL B1818T by morphological, physiological and biochemical characteristics. Based on these data, strain GGCR-6T should be designated as a representative of a novel species of the genus Streptomyces, for which the name Streptomyces aquilus sp. nov. is proposed. The type strain is strain GGCR-6T (=CICC 11055T=JCM 33584T).

Epigenetic Modulation of Endophytic Eupenicillium sp. LG41 by a Histone Deacetylase Inhibitor for Production of Decalin-Containing Compounds.

An endophytic fungus, Eupenicillium sp. LG41, isolated from the Chinese medicinal plant Xanthium sibiricum, was subjected to epigenetic modulation using an NAD+-dependent histone deacetylase (HDAC) inhibitor, nicotinamide. Epigenetic stimulation of the endophyte led to enhanced production of two new decalin-containing compounds, eupenicinicols C and D (3 and 4), along with two biosynthetically related known compounds, eujavanicol A (1) and eupenicinicol A (2). The structures and stereochemistry of the new compounds were elucidated by extensive spectroscopic analysis using LC-HRMS, NMR, optical rotation, and ECD calculations, as well as single-crystal X-ray diffraction. Compounds 3 and 4 exist in chemical equilibrium with two and three cis/trans isomers, respectively, as revealed by LC-MS analysis. Compound 4 was active against Staphylococcus aureus with an MIC of 0.1 µg/mL and demonstrated marked cytotoxicity against the human acute monocytic leukemia cell line (THP-1). We have shown that the HDAC inhibitor, nicotinamide, enhanced the production of compounds 3 and 4 by endophytic Eupenicillium sp. LG41, facilitating their isolation, structure elucidation, and evaluation of their biological activities.

Actinophytocola xanthii sp. nov., an actinomycete isolated from rhizosphere soil of the plant Xanthium sibiricum.

A novel actinomycete strain, 11-183T, was isolated from the rhizosphere soil of Xanthium sibiricum, which was collected in Tangshan, Hebei, China. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain 11-183T formed a clade within the genus Actinophytocola, with a maximum similarity of 98.44 % to Actinophytocola xinjiangensis QAIII60T, followed by 97.76 % similarity to Actinophytocola sediminis YIM M13705T. The average nucleotide identity and digital DNA-DNA hybridization values differed by 79.24 and 23.4 %, respectively, between strain 11-183T and Actinophytocolaxinjiangensis QAIII60T. Strain 11-183T grew well on N-Z-amine agar, and it produced a scant, white aerial mycelium. The isolate formed pale yellow to brown-black colonies and a dense, non-fragmented, branched substrate mycelium, and produced aerial hyphae on which nodular spore chains formed. Growth was observed at salinities ranging from 0 to 2 %, at pH values ranging from pH 6.5 to 8.0 and at temperatures ranging from 15 to 37 °C. The cell-wall amino acids included meso-diaminopimelic acid. Whole cell hydrolysates contained galactose and glucose. The principal fatty acids were iso-C16 : 0, iso-C16 : 1 H and C17 : 1ω6c. Diphosphatidylglycerol, phosphatidylmonomethylethanolamine and phosphatidylethanolamine were the diagnostic phospholipids. The isoprenoid quinones included MK-9(H4) and MK-10(H4). The G+C content of the genomic DNA was 71.7 mol%. Based on the genotypic and phenotypic data, we conclude that strain 11-183T belongs to a novel species of the genus Actinophytocola. The name proposed for the novel species is Actinophytocola xanthii sp. nov., with the type strain 11-183T (=KCTC 39690T= MCCC 1K02062T).

Influence of Processing on the Content of Toxic Carboxyatractyloside and Atractyloside and the Microbiological Status of Xanthium sibiricum Fruits (Cang'erzi).

The dried ripe fruits of Xanthium sibiricum (Cang'erzi) are used in traditional Chinese medicine for the treatment of nasal congestion, nasal discharge, allergic rhinitis, sinusitis, and wind-cold headaches. Carboxyatractyloside and atractyloside are important constituents of the fruits because these diterpenoid glycosides are responsible for their toxicity. In order to evaluate procedures for reducing the amount of the more toxic carboxyatractyloside, the fruits were dried and heated with different methods. Carboxyatractyloside and atractyloside were analysed by a new reversed-phase high-performance liquid chromatographic method using liquid chromatography-diode array detector-tandem mass spectrometry analysis. The results revealed that temperature and drying methods have a strong influence on the content of carboxyatractyloside and atractyloside. Fruits which were treated at higher temperatures showed a lower content of carboxyatractyloside and an increased content of atractyloside, which is 50 times less toxic. This indicates that the roasting process can reduce toxicity effectively. The microbiological colonisation of Xanthium fruits is also reduced by roasting and by drying above 100 °C. For the safe use of Cang'erzi, the effect of processing should be monitored and analysis of carboxyatractyloside and atractyloside should be obligatory in quality control.

Xanthium italicum, Xanthium strumarium and Arctium lappa as new hosts for Diaporthe helianthi.

Sunflower (Helianthus annuus) stem canker caused by Diaporthe helianthi is one of the most important sunflower diseases in Croatia. Until recently, sunflower was the only known host for D. helianthi. In our research carried out in the area of Eastern Croatia, isolates of Diaporthe/Phomospis were collected from Xanthium italicum, X. strumarium and Arctium lappa. Using morphological, cultural and molecular ITS rDNA data, isolates from these weeds were identified as D. helianthi. The following isolates were used in the pathogenicity test: one isolate originated from sunflower (Su5/04), three from X. italicum (Xa2, Xa3 and Xa5), two from X. strumarium (Xa9 and Xa12), one from Xanthium sp. (Xa13) and one from A. lappa (Ar3). According to the results, it was determined that isolate Xa5 (originated from X. italicum) was the most pathogenic to sunflower stems. The average length of the lesion was 11.3 cm. The lowest level of pathogenicity was found in Xa9 (isolated from X. strumarium). The length of the lesion was 0.1 cm.