Antimicrobial potential of endophytic fungi from Astragalus chinensis
The purpose of the present study was to discover antimicrobial endophytic fungi from Astragalus chinensis. Three fungal endophytes with antibacterial activity were isolated and determined as Chaetomium sp. HQ-1, Fusarium sp. HQ-7 and Fusarium sp. HQ-9 based on the neighbor-joining phylogenetic tree. Chaetomium sp. HQ-1 showed the best antibiotic potential and was thus selected for large-scale fermentation. Bioactivity-directed separation of ME fermentation of strain HQ-1 led to the discovery of three compounds, which were identified as differanisole A (1), 2,6-dichloro-4-propylphenol (2) and 4,5-dimethylresorcinol (3), from the HR–ESI–MS and NMR data analysis. All three compounds exhibited moderate antibacterial activity against Listeria monocytogenes, Staphylococcus aureus, and methicillin-resistant S. aureus, with MIC values ranging from 16 to 128 μg/mL. Compounds 1 and 3 also displayed promising antifungal activity against Selerotium rolfsii with IC50 values of less than 16 and 32 μg/mL, respectively, which were comparable to that of actidione (8 μg/mL). The findings of the present study suggest that the endophytic fungi from A. chinensis have the potential to be used as bactericides and fungicides.
KeywordsEndophyte Astragalus chinensis Chaetomium sp. Antibiotic Differanisole A
This work was supported by the National Natural Science Foundation of China (21602152), Shandong Provincial Natural Science Foundation (ZR2016BB01), Shandong Provincial Key Laboratory of Agricultural Microbiology Open Fund (SDKL2017015).
PL, DZ and RS performed the experiments and analyzed data. ZY and FZ edited the manuscript. YT designed the experiments. All authors revised the manuscript. All authors read and approved the final manuscript.
Compliance with ethical standards
Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
- Asgari B, Zare R (2011) The genus Chaetomium in Iran, a phylogenetic study including six new species. Mycologia 103(4):863–882Google Scholar
- Christie RM, Rickards RW, Schmalzl KJ, Taylor D (1977) Ring contraction of 4-substituted 2, 6-dichlorophenols. The crystal structure of 2, 2, 4α, 5α-tetrachloro-1α, 3α-dihydroxycyclopentane-1, 4-carbolactone. Aust J Chem 30(10):2195–2204Google Scholar
- Fan YP, Hu YL, Wang DY, Liu JG, Zhang J, Zhao XJ, Liu X, Liu C, Yuan J, Ruan S (2012) Effects of Astragalus polysaccharide liposome on lymphocyte proliferation in vitro and adjuvanticity in vivo. Carbohydr Polym 88:68–74Google Scholar
- Golinska P, Wypij M, Agarkar G, Rathod D, Dahm H, Rai M (2015) Endophytic actinobacteria of medicinal plants: diversity and bioactivity. Anton Leeuw 108:267–289Google Scholar
- Jogi A, Kerry JW, Brenneman TB, Leebens-Mack JH, Gold SE (2016) Identification of genes differentially expressed during early interactions between the stem rot fungus (Sclerotium rolfsii) and peanut (Arachis hypogaea) cultivars with increasing disease resistance levels. Microbiol Res 184:1–12PubMedGoogle Scholar
- Kanatani Y, Makishima M, Ken-i Asahi, Sakurai A, Takahashi N, Motoyoshi K, Nagata N (1997) Differanisole A, a novel antitumor antibiotic, enhances growth inhibition and differentiation of human myeloid leukemia cells induced by 9-cis retinoic acid. BBA Mol Cell Res 1359:71–79Google Scholar
- Li R, Chen WC, Wang WP, Tian WY, Zhang XG (2010) Antioxidant activity of Astragalus polysaccharides and antitumour activity of the polysaccharides and siRNA. Carbohydr Polym 82(2):240–244Google Scholar
- Li H, Tian JM, Tang HY, Pan SY, Zhang AL, Gao JM (2015) Chaetosemins A–E, new chromones isolated from an Ascomycete Chaetomium seminudum and their biological activities. RSC Adv 5:29185–29192Google Scholar
- Liu X, Li H, Zhou F, Wang R (2015) Secondary metabolites of Fusarium sp., an endophytic fungus in Astragalus membranaceus. Chem Nat Compd 51(6):1199–1201Google Scholar
- Mazinani Z, Zamani M, Sardari S (2017) Isolation and identification of phyllospheric bacteria possessing antimicrobial activity from Astragalus obtusifolius, Prosopis juliflora, Xanthium strumarium and Hippocrepis unisiliqousa. Avicen J Med Biotechnol 9(1):31–37Google Scholar
- Newman DJ, Cragg GM (2016) Natural products as sources of new drugs from 1981 to 2014. J Nat Prod 79(3):629–661Google Scholar
- Schulz B, Wanke U, Draeger S, Aust HJ (1993) Endophytes from herbaceous plants and shrubs: effectiveness of surface sterilization methods. Mycol Res 97:1447–1450Google Scholar
- Sharma D, Pramanik A, Agrawal PK (2016) Evaluation of bioactive secondary metabolites from endophytic fungus Pestalotiopsis neglecta BAB-5510 isolated from leaves of Cupressus torulosa D.Don. 3 Biotech 6(210):1–14Google Scholar
- Spellberg B (2012) New antibiotic development: barriers and opportunities in 2012. APUA Clin Newsl 30:8–10Google Scholar
- Vuong C, Yeh AJ, Cheung GYC, Otto M (2016) Investigational drugs to treat methicillin-resistant Staphylococcus aureus. Expert Opin Investig Drug 25(1):73–93Google Scholar
- Zhao SS, Zhang YY, Yan Y, Cao LL, Xiao Y, Ye YH (2017) Chaetomium globosum CDW7, a potential biological control strain and its antifungal metabolites. FEMS Microbiol Lett 364(3):1–6Google Scholar