Genome analysis and plant growth promoting activity of Pseudonocardia strain DR1-2 from the root of Dendrobium christyanum Rchb.f

Aims@#The objective of this study was to analyze the genome of endophytic actinomycete associated with orchids and evaluate its plant hormone activities, including phytohormone, siderophore, ammonia production, zinc and phosphate solubilization.@*Methodology and results@#Strain DR1-2 isolated from the roots of the Thai orchid, Dendrobium christyanum Rchb.f., was closely related to Pseudonocardia alni DSM 44104T, P. antarctica DSM 44749T and P. carboxydivorans Y8T (99.93-100% similarity) based 16S rRNA gene sequence. This strain exhibited IAA production (294.10 ± 12.17 μg/mL), phosphate solubilization (2.20 ± 0.08 solubilization Index, SI), positive for siderophore production and ammonia production (36.99 ± 2.24 μg/mL). It showed a maximum IAA of 489.73 ± 8.90 μg/mL, when optimized using 0.5% Ltryptophan, pH 6 and incubated at 30 °C for 7 days. The IAA of strain enhanced the root length, shoot length, number of roots and fresh weight of rice seedlings (Oryza sativa L. cv. RD49). The draft genome of strain DR1-2 was 6,077,423 bp in 23 contigs with G+C content of 74.6%. The average nucleotide identity-Blast (ANIb) and average nucleotide identity-MUMmer (ANIm) values of strain DR1-2 and related type strains were 95.81 to 97.25% and the digital DNA-DNA hybridization (dDDH) values were 72.60 to 74.00%, respectively. Genomic analysis of strain DR1-2 revealed that the gene encodes the enzyme involved in the phytohormones biosynthesis and gene clusters involved in the biosynthesis of bioactive metabolites.@*Conclusion, significance and impact of study@#Endophytic actinomycete, Pseudonocardia strain DR1-2 from Thai orchid, D. christyanum Rchb.f., exhibited significant IAA production and affected the growth of the plant, which was the potential source of plant hormones for agricultural applications.

Antiviral activity of geldanamycin and its derivatives against influenza virus

Two new geldanamycin derivatives such as 17-(tryptamine)-17-demethoxygeldanamycin (2) andC17 methoxyl of geldanamycin (1). Their antiviral activity was evaluated based on influenza virus propagation inembryonated chicken eggs and viral absorption by hemagglutination (HA) inhibition test. The findings indicatedthat these compounds inhibited viral propagation at a concentration of 12.5 µg/ml. For the viral absorption, onlycompounds 2 and 3 inhibited HA at a concentration of 50 µg/ml. The solubility of compounds 2 and 3 in waterwas 290 and 306 µM, higher than that of compound 1 about 1.91 and 2.01 times, respectively. The compounds 2and 3 showed a moderate cytotoxic activity on LLC-MK2 and Vero cells with IC50 values of >200.00 µg/ml. Theseresults demonstrated the invention of tryptamine-geldanamycin hybrids to prevent influenza virus infection in viralabsorption and viral propagation steps.

Endophytic Actinomycetes as Potential Producers of Hemicellulases and Related Enzymes for Plant Biomass Degradation

Abstract Tailor made enzymatic preparation must be design to hydrolyze efficiently plant biomass, once that each plant biomass possesses a distinct cell wall composition. Most of actinomycetes used for plant cell wall degradation are focused on the cellulases and xylanases production. However, a wide range of enzymes must be produced for an efficient degradation of lignocellulose materials. During the last decade several unusual environments were studied to obtain strains that produce glycohydrolases with innovator characteristics. In this context, the present work concerned the selection of endophytic actinomycetes as producers of hemicellulases and related enzymes with different enzymatic profiles, for use in the deconstruction of lignocellulosic biomass. A total of 45 Brazilian actinomycetes previously isolated from plants (endophytics) and soil were prospected for hemicellulases and β-glucosidase production. Four strains highlighted for hemicellulase production (DR61, DR63, DR69 and DR66) and were selected for cultivation under other inductors substrates (xylan and pectin). All strains belong to Streptomyces genera and have their extracts tested for degradation of several hemicellulolytic substrates. The strains presented different glicohydrolyse enzymes profiles mainly for xylans and glucans that can be used for specific formulations of enzymes applied on the biomass deconstruction, principally on sugar cane bagasse.

Antimicrobial activity and identification of endophytic actinomycetes strain 13-85 isolated from Acanthopanax senticosus / 中草药

Objective: To studies the antimicrobial activity and stability of fermentation extracts produced by endophytic actinomycete strain 13-85 from Acanthopanax senticosus; Secondary metabolite biosynthesis genes were detected. Meanwhile, the strain was identified. Methods: Paper disc diffusion method was used to test the antimicrobial activity and stability of strain 13-85, the biosynthesis genes (PKS I, PKS II, NRPS, Halo, and CYP) were obtained by PCR, and sequences were analyzed. The strain was identified by phenotypic characteristics and molecular characteristics. Results: The fermentation broth of the strain showed broad-spectrum, strong activity, and stability against pathogenic microbes. The strain contains PKS II gene and NRPS gene. The PKS II sequence had 89% homology compared with Streptomyces fradiae PKS gene (Accession Number: AFO70128.1). The NRPS gene sequence had 95% homology with S. virginiae NRPS gene (Accession Number: WP_033225509.1). The sequence of 16S rRNA of the strain had 99.85% homology with S. amritsarensis (Accession Number: GQ906975). Conclusion: Metabolites of the actinomycete strain 13-85 with broad-spectrum antibacterial activity and better stability, have a value for development and application. The strain 13-85 was identified as Streptomyces amritsarensis, a valid species of genus Streptomyces.

Diversity, bioactivities, and metabolic potentials of endophytic actinomycetes isolated from traditional medicinal plants in Sichuan, China / 中国天然药物

The present study was designed to determine the taxonomic diversity and metabolic activity of the actinomycetes community, including 13 traditional medicinal plants collected in Sichuan province, China, using multiple approaches such as morphological and molecular identification methods, bioactivity assays, and PCR screening for genes involved in antibiotics biosynthesis. 119 endophytic actinomycetes were recovered; 80 representative strains were chosen for 16S rRNA gene partial sequence analyses, with 66 of them being affiliated to genus Streptomyces and the remaining 14 strains being rare actinomycetes. Antimicrobial tests showed that 12 (15%) of the 80 endophytic actinomycetes displayed inhibitory effects against at least one indicator pathogens, which were all assigned to the genus Streptomyces. In addition, 87.5% and 58.8% of the isolates showed anticancer and anti-diabetic activities, respectively. Meanwhile, the anticancer activities of the isolates negatively correlated with their anti-diabetic activities. Based on the results of PCR screening, five genes, PKS-I, PKS-II, NRPS, ANSA, and oxyB, were detected in 55.0%, 58.8%, 90.0%, 18.8% and 8.8% of the 80 actinomycetes, respectively. In conclusion, the PCR screening method employed in the present study was conducive for screening and selection of potential actinomycetes and predicting potential secondary metabolites, which could overcome the limitations of traditional activity screening models.

The Screen of Plant Endophytic Actinomycetes Producing ?-1,3-Glucanase and Antifungal Activity of ?-1,3-Glucanase / 微生物学通报

Using of clearing zones on pachyman agar medium, there are 217 plant endophytic actinomycetes, producing ?-1,3-glucanase were screened. 45.6% of the strains produced ?-1,3-glucanase, in which the strains from cucumber are up to 38. The percentages of endophytic actinomycetes from different hosts produceing ?-1,3-glucanases were different. The percentage of the strains in Rhizoma Polygonatum produced ?-1,3-glucanases is the highest, up to 88.9%. The Inhibited effects of plant endophytic actinomycetes which produced extracellular ?-1,3-glucanases on mycelium growth of Sclerotinia sclerotiorum were detected in vitro. Cucumber endophytic actinomycete gCLA4 strain was screened out from 99 isolates, which can strongly inhibit the growth of S. sclerotiorum. The optimal ?-1,3-glucanases fermentation conditions of strain gCLA4 were investigated, they were pachyman 0.2%, peptone as nitrogen, pH 7～8 for 5 days. The ?-1,3-glucanases of strain gCLA4 had some inhibiting efficiency on 13 plant pathogens, in which inhibiting efficiency to Botryosphaeria dothidea was the strongest.