地衣型真菌次级代谢产物抗菌活性初步研究

Antimicrobial activity of secondary metabolites from lichen forming fungi

关键词:  地衣型真菌, 次级代谢产物, 抗菌活性, 抑菌圈法, 液体培养

Key words:  Lichen forming fungi, secondary metabolites, antimicrobial activity, inoculating inhibition zone, liquid culture

摘要:

地衣是一种传统的民族药物,能产生多种具有活性的物质。该研究对地衣型真菌(Xanthoria elegans, Myelochroa indica, Ramalina peruviana, Cladonia macilenta, Nephromopsis pallescens, Cladonia coccifera)进行液体培养,2个月后,培养液用乙酸乙酯萃取后获得初提物。该研究采用抑菌圈法评价地衣型真菌初提物对7种致病细菌(Bacillus subtilis, Bacillus cereus, Vibrio parahaemolyticus, Straphylococcus haemolyticus, Pseudomonas aeruginosa, Staphylococcus aureus, Micrococcus luteus)的抗菌活性,并测定最低抑菌浓度(MIC)。结果表明:6种地衣型真菌的初提物均具有一定的抗菌活性,且不同培养基对地衣型真菌产生抗菌物质有显著影响。其中,R. peruviana在MY液体培养基中所产生的次级代谢产物对金黄色葡萄球菌、藤黄微球菌、溶血性葡萄球菌、铜尿假单胞菌具有抑制效果,但在YMG培养基中所得初提物对供试7种致病细菌不具有抑菌效果。X. elegans在YMG培养基中所得初提物对枯草芽孢杆菌具有明显抗菌活性,其抑菌圈直径可达17.77 mm。该研究证实不同地衣型真菌液体培养初提物具有抗菌活性,不同的培养基也直接影响地衣型真菌抗菌效果。该研究结果为地衣型真菌的进一步研究及民族药的开发利用奠定了基础。

Abstract:

Lichen is a traditional ethnic medicine,which produces numerious active components. Thus, lichens have high research value. Most of antimicrobial ingredients from lichens were produced by lichen forming fungi. In order to detect the antimicrobial activity of secondary metabolites from lichen forming fungi, the fungi(Xanthoria elegans, Myelochroa indica, Ramalina peruviana, Cladonia macilenta, Nephromopsis pallescens and Cladonia coccifera)were cultured in liquid medium for two months. The secondary metabolites of lichen forming fungi were obtained by extracting with ethyl acetate, and then the extracts were weighed and dissolved in DMSO. Seven kinds of pathogenic bacteria(Bacillus subtilis, B. cereus, Vibrio parahaemolyticus, Straphylococcus haemolyticus, Pseudomonas aeruginosa, Staphylococcus aureus and Micrococcus luteus)were used to screen activity of the extracts. Inoculating inhibition zone was used to evaluate the antibacterial activity of the extracts, and the minimum inhibitory concentration with antibacterial activity was also detected. The results showed that all of primary extract of lichen forming fungi had extensive antibacterial activity, and the antibacterial activity of the same fungi cultured showed significantly difference in different media. The secondary metabolites produced by Ramalina peruviana cultured in MY liquid medium had inhibitory effect to Straphylococcus aureus, Straphylococcus haemolyticus, Pseudomonas aeruginosa and Micrococcus luteus. It showed that the primary extract from Ramalina peruviana had extensive antibacterial effect. But the secondary metabolites of R. peruviana cultured in YMG liquid medium had not inhibitory effect to all of these pathogenic bacteria. Extracts from all of lichen forming fungi cultured in YMG liquid medium, Only the extract of Cladonia coccifera inhibited the Staphylococcus aureus which is gram-negative bacteria. The primary extract produced by Xanthoria elegans cultured in YMG medium had antibacterial effect to Bacillus cereus, the diameter of inhibition zone was up to 17.77 mm. Our results confirmed that the secondary metabolites of lichen forming fungi have antimicrobial activity and the lichen forming fungi can produce bioactive secondary metabolites in laboratorial culture conditions. Experiment results also showed that different media can stimulate different lichen forming fungi to produce different components. The innovation of this study was that different media were used to culture lichen forming fungi and lichen forming fungi had the characteristics of one strain many compounds. This study provides the groundwork to identify the active ingredients from lichens and provides an important information for culturing mass lichens to obtain bioactive compounds.