木麻黄内生真菌次生代谢产物及生物活性

    Secondary metabolites of endophytic fungi isolated from Casuarina equisetifolia and their bioactivities

    • 摘要:
      目的  分离和鉴定木麻黄Casuarina equisetifolia枝条和果实中的内生真菌,筛选具有抗菌和抗氧化活性的内生真菌。
      方法  采用组织块分离法分离木麻黄枝条和果实中的内生真菌,通过菌落观察和分子生物学相结合的方法对分离到的内生真菌进行鉴定;采用薄层层析−生物自显影法测定木麻黄内生真菌次生代谢产物对细菌的抑制活性,采用多孔板−DPPH显色法测定抗氧化活性。
      结果  从木麻黄枝条和果实中共分离鉴定得到12株内生真菌,枝条和果实内生真菌存在明显的差异,相同的菌株只有2株,分别为Cef-1(Pseudofusicoccum sp.)和Cef-7(Pestalotiopsis sp.);12株内生真菌分属于9个不同的属中,分别为Pseudofusicoccum、葡萄座腔菌属Botryosphaeria、拟盘多毛孢属Pestalotiopsis、木霉属Trichoderma、曲霉属Aspergillus、裂菌属Rhytidhysteron、拟茎点霉属Phomopsis、镰刀菌属Fusarium和炭疽菌属Colletotrichum。其中,葡萄座腔菌属种类最多,为木麻黄内生真菌的优势种群,其次是拟盘多毛孢属真菌。抗细菌活性的结果表明,Cef-2(Botryosphaeria sp.)表现出最强的抑制活性,对所有供试细菌的抑菌斑直径均大于10 mm,强于阳性对照硫酸链霉素,Cef-1和Cef-9(Fusarium sp.)对青枯病菌Ralstonia solanacearum也表现出较好的抑制活性。内生真菌Cef-2表现出最好的抗氧化活性,IC50为0.80 mg/mL。
      结论  木麻黄枝条和果实中均存在内生真菌且均以葡萄座腔菌属为优势种群,2个部位真菌的种类存在明显差异。内生真菌Cef-2表现出最强的抗细菌和抗氧化活性,可作为候选菌株进一步分离和鉴定其活性成分。

       

      Abstract:
      Objective  To isolate and identify endophytic fungi from branches and fruits of Casuarina equisetifolia Forst., and screen active endophytic fungi with antibacterial and antioxidant activities.
      Method  Endophytic fungi from branches and fruits of C. equisetifolia were isolated by the tissue block separation method, and identified by combining colony observation with molecular biology. The antibacterial activities of secondary metabolites produced by endophytic fungi against different bacteria were determined using TLC-bioautography and their antioxidant activities were determined using the multi-orifice plate-DPPH coloration method.
      Result  Twelve strains were isolated and identified from branches and fruits of C. equisetifolia. There were significant difference between endophytic fungi isolated from branches and fruits. There were only two same endophytic fungus strains in branches and fruits, namely Cef-1 (Pseudofusicoccum sp.) and Cef-7 (Pestalotiopsis sp.). All endophytic fungi were mainly distributed in nine different genera, including Pseudofusicoccum, Botryosphaeria, Pestalotiopsis, Trichoderma, Aspergillus, Rhytidhysteron, Phomopsis, Fusarium and Colletotrichum. Among them, Botryosphaeria had the most species and was the dominant species, followed by Pestalotiopsis. Cef-2 (Botryosphaeria sp.) showed the strongest inhibitory activity and the diameters of antibacterial spots were more than 10 mm, which were stronger than that of the positive control streptomycin sulfate. Cef-1 and Cef-9 (Fusarium sp.) showed well inhibition on Ralstonia solanacearum. Cef-2 displayed the best antioxidant activity and the IC50 value was 0.80 mg/mL.
      Conclusion  There are endophytic fungi in branches and fruits of Casuarina equisetifolia, and Botryosphaeria is the dominant species. There are significant differences of fungi species between branches and fruits. Endophytic fungus Cef-2 exhibits the strongest antibacterial and antioxidant activities, which can be used as a candidate strain for further isolation and identification of active component.

       

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