Cultivable endophytic fungal community associated with the karst endemic plant Nervilia fordii and their antimicrobial activity.

Endophytic fungi from medicinal plants with specific pharmacological functions attract much attention to provide the possibility of discovering valuable natural drugs with novel structures and biological activities. Nervilia fordii is a rare and endangered karst endemic plant that is used as medicine and food homology in Guangxi, China. These plants have been reported to have antimicrobial, antitumor, antiviral, and anti-inflammatory activities. However, few studies have focused on the diversity and antibacterial activity of endophytic fungi from N. fordii. In the present study, 184 endophytic fungi were isolated from the healthy tissues of N. fordii, and their molecular diversity and antimicrobial activities were analyzed for the first time. These fungi were categorized into 85 different morphotypes based on the morphological characteristics and the similarity between the target sequence and the reference sequence in the GenBank database. With the exception of 18 unidentified fungi, the fungal isolates belonged to at least 2 phyla, 4 classes, 15 orders, 45 known genera, and 45 different species, which showed high abundance, rich diversity, and obvious tissue specificity. All isolates were employed to screen for their antimicrobial activities via the agar diffusion method against Escherichia coli, Staphylococcus aureus, and Candida tropicalis. Among these endophytes, eight strains (9.41%) displayed inhibitory activity against E. coli, 11 strains (12.94%) against S. aureus, and two strains (2.35%) against C. tropicalis, to some extent. In particular, our study showed for the first time that the fungal agar plugs of Penicillium macrosclerotiorum 1151# exhibited promising antibacterial activity against E. coli and S. aureus. Moreover, the ethyl acetate (EA) extract of P. macrosclerotiorum 1151# had antibacterial effects against E. coli and S. aureus with a minimum inhibitory concentration (MIC) of 0.5 mg ml-1. Further research also confirmed that one of the antimicrobial compounds of P. macrosclerotiorum 1151# was methyl chloroacetate and exhibited excellent antibacterial activity against E. coli and S. aureus up to 1.71-fold and 1.13-fold compared with tetracycline (TET) (5 mg ml-1), respectively. Taken together, the present data suggest that various endophytic fungi of N. fordii could be exploited as sources of novel natural antimicrobial agents.

[Genetic diversity and antibacterial activity of endophytic fungi from Zanthoxylum nitidum].

In order to reveal the distribution and population characteristics of endophytic fungi from Zanthoxylum nitidum and the antibacterial potential,this study performed molecular identification and analyzed the genetic diversity and antibacterial activity of endophytic fungi from Z. nitidum in Guangxi. Through culture and molecular identification,35 strains,belonging to 15 genera,12 families,10 orders,4 classes,and 2 phyla,were isolated from various tissues of Z. nitidum,of which Colletotrichum and Fusarium were the dominant genera,respectively accounting for 20% of total strains. The diversity of endophytic fungi was significantly different among roots,stems,and leaves,as manifested by the significantly higher Shannon index( H') in stems( 1. 678) than in roots( 0. 882 1) and leaves( 0. 515 4). The antimicrobial activity analysis showed that 14. 28% of endophytic fungi inhibited at least one indicator pathogen. Among them,Fusarium sp. ZN-34 and Fusarium sp. ZN-26 separately demonstrated the strongest inhibitory effect on Escherichia coli and Staphylococcus aureus. In general,Fusarium sp. ZN-26 and Phialemoniopsis plurioloculosa ZN-35 were advantageous in suppressing the two bacteria owing to the broad spectrum and strong efficacy. In summary,Z. nitidum in Guangxi boasts rich endophytic fungi with the majority showing strong antibacterial activity,which can be used as candidates for the extraction and separation of basic antibacterial substances and the development of natural antibacterial agents.

[Effects of exogenous IBA and fungal elicitor on growth of in vitro roots culture of Dysosma versipellis and production of podophyllotoxin].

Using the White as basic medium, the effects of the exogenous IBA and endophytic fungal elicitor on the growth of in vitro roots cultures of Dysosma versipellis and production of podophyllotoxin were investigated in this study. The results showed that the IBA and the endophytic fungus Zasmidium syzygii elicitor could increase the content of podophyllotoxin of in vitro roots of D. versipellis after 3 weeks. The White medium added with 3 mg·L~(-1) IBA induced the highest increase of podophyllotoxin(1 830.86 µg·g~(-1)), which was 2.07 folds greater than the control, and followed by 1.5 mg·L~(-1) IBA, fungal elicitor, 1 mg·L~(-1) IBA, 0.5 mg·L~(-1) IBA and 4.5 mg·L~(-1) IBA, which was 1.82, 1.71, 1.63, 1.43 and 1.1 folds greater than the control, respectively. The results also showed that the growth of roots was certain positively correlated with the change of IBA concentration. Therefore, 3 mg·L~(-1) IBA was the most suitable for the production of podophyllotoxin in the in vitro roots of D. versipellis, and the stimulating effect of Z. syzygii fungal elicitor was between 1.5 mg·L~(-1) and 1 mg·L~(-1) IBA, which was a potential natural elicitor to induce the accumulation of podophyllotoxin in future production.

[Inhibitory effect of endophytic fungi from Dysosma versipellis on HIV-1 IN-LEDGF/p75 interaction].

To determine the inhibitory effect of endophytic fungi from Dysosma versipellis on HIV-1 IN-LEDGF/p75 interaction,the protein-protein interaction between human immunodeficiency virus type 1( HIV-1) integrase and lens epithelial growth factor p75 protein( LEDGF/p75) was used as a target. The homogeneous time-resolved fluorescence( HTRF) technique was used in the inhibitory activity assay. The results showed that eight endophytic fungi with anti-IN-LEDGF/p75 interaction activity were screened out from fifty-three strains with different morphological characteristic. Among them,106 strain showed strong inhibitory activity against HIV-1 IN-LEDGF/p75 interaction with IC50 value of 5. 23 mg·L-1,and was identified as a potential novel species of Magnaporthaceae family by the analyses of ITS-rDNA,LSU and RPB2 sequences data. This study demonstrated that potential natural active ingredients against the HIV-1 IN-LEDGF/p75 interaction exist in the endophytic fungi of D. versipellis. These results may provide available candidate strain resources for the research and development of new anti-acquired immunodeficiency syndrome drugs.

Author Correction: Diversity and bioactive potential of culturable fungal endophytes of Dysosma versipellis; a rare medicinal plant endemic to China.

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Diversity and bioactive potential of culturable fungal endophytes of Dysosma versipellis; a rare medicinal plant endemic to China.

The plant Dysosma versipellis is known for its antimicrobial and anticancer properties but is a rare and vulnerable perennial herb that is endemic to China. In this study, 224 isolates were isolated from various tissues of D. versipellis, and were classified into 53 different morphotypes according to culture characteristics and were identified by sequence analyses of the internal transcribed spacer (ITS) region of the rRNA gene. Although nine strains were not assignable at the phylum level, 44 belonged to at least 29 genera of 15 orders of Ascomycota (93%), Basidiomycota (6%), and Zygomycota (1%). Subsequent assays revealed antimicrobial activities of 19% of endophytic extracts against at least one pathogenic bacterium or fungus. Antimicrobial activity was also determined using the agar diffusion method and was most prominent in extracts from four isolates. Moreover, high performance liquid chromatography (HPLC) and ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry analyses (UPLC-QTOF MS) showed the presence of podophyllotoxin in two Fusarium strains, with the highest yield of 277 µg/g in Fusarium sp. (WB5121). Taken together, the present data suggest that various endophytic fungi of D. versipellis could be exploited as sources of novel natural antimicrobial or anticancer agents.

[Microscopic observation on mycorrhiza of rare herb Dysosma versipellis].

Endophytic fungi played an important role in the growth of its host plant. To investigate the mycorrhizal characteristics and the distribution of fungi in the root, an endangered wild plant-Dysosma versipellis was collected and observed by electron microscope. The results showed that the host was closely associated with endophytic fungi. The fungi were mainly distributed in the epidermis and cortex. The aseptate and septate fungi with swollen hyphae were observed in some cell of the cortex. The result provides a reference for the study of mycorrhizal structure of Dysosma genus and the interaction between the fungi and its host.

[Infrared radiation and magnetic field therapy ameliorates cartilage damage in rabbits with knee osteoarthritis].

OBJECTIVE: To evaluate the effect of infrared radiation and magnetic field therapy on cartilage damage in rabbits with knee osteoarthritis. METHODS: Knee osteoarthritis was induced in 24 adult New Zealand rabbits by prolonged fixation of the knee joint in extension for 6 weeks. The rabbits were subsequently randomized into control group (without treatment), infrared therapy group, magnetic field therapy group and the combined infrared and magnetic field therapy group. At the end of the first, second and third weeks of the therapy, respectively, 2 rabbits from each group were sacrificed to observe the general changes and histopathology of the condylar cartilage of the femur, and the findings were assessed using Mankin scores. RESULTS: Compared with other groups, the rabbits in the combined therapy group showed significantly milder cartilage damage (including injury of the cartilage surface and chondrocyte's proliferation and disarrangement) with significantly lower Mankin scores (P<0.05). No significant differences were found in the findings between the two groups with exclusive infrared or magnetic field therapy (P>0.1). CONCLUSION: Combined infrared and magnetic field therapy can effectively alleviate cartilage destruction, shortens the disease course and enhance the therapeutic effects in rabbits with knee osteoarthritis.