Abstract
In order to search more antimicrobial natural products for new drug discovery, bioassay and chemical investigation of endophytic strains from Rumex madaio were carried out. Six fungal strains (numbered as L1, L6, L9, L10, R1, R2) were successfully isolated and their antimicrobial effects on three human pathogens, Escherichia coli, Staphyloccocus aureus and Candida albicans, were evaluated. The results indicated that ethyl acetate extracts of fermentation broth of these strains had no potent antimicorbial activity against E. coli and C. albicans while strains L1 and R1 had stronger inhibitory effects on S. aureus. On basis of morphological characteristics and 18S rRNA sequence analysis, strains L1 and R1 were respectively classified as Colletotrichum and Fusarium geni. The chemical study of strain R1 led to isolation of two known antimicrobial agents, dibutyl phthalate (1) and beauvericin (2).
Highlights
Endophyte, one of special microorganisms, resides in the intracellular or intercellular area of healthy plant tissues during their periods of life or the whole (Zhang et al, 2006; Zhang et al, 2018)
Bioassay results indicated that all crude extracts of endophytic strains had no antimicrobial activities against E. coli and C. albicans at the concentrations ranging from 0.1 to 10 mg/mL (Table I)
Strain L9 cultured in salted PDB exhibited moderate inhibitory effect on S. aureus at 10 mg/mL
Summary
One of special microorganisms, resides in the intracellular or intercellular area of healthy plant tissues during their periods of life or the whole (Zhang et al, 2006; Zhang et al, 2018). In this symbiotic system, host plants and endophytes maintain a win-win relationship between species. Endophytic microbe could service as an alternative source to make valuable natural products (Yadav et al, 2014)
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