桦木内生真菌的分离与代谢产物的抑菌活性

Antimicrobial activity of metabolites and isolation of endophytic fungi in Betula spp.

通过琼脂块法和滤纸片法,对白桦Betula platyphylla、棘皮桦B.dahurica、硕桦B.costata和柴桦B.fruticosa）的内生真菌产生抑菌物质的特性进行研究,结果表明分离自白桦3年生枝条的内生真菌拟茎点霉Phomopsis sp.BP103381表现出较强的抑菌物质形成能力。采用正交设计优化了BP103381的培养条件,在含有40 g/L蔗糖、3 g/L NaNO3、1 g/LMgSO4的改良查氏液体培养基中,在pH值6.5、28℃条件下发酵培养9 d,有利于抑菌活性物质的形成。BP103381产生的抑菌活性物质具有较好的温度稳定性,但是酸碱变化对抑菌物质的活性影响较大,BP103381产生的抑菌物质在pH为5.0~7.0时活性较强。

The strain producing antibiotic was obtained by agar-piece diffusion and paper-disc diffusion method from the endophytic fungi in Betula platyphylla,B.dahurica,B.costata and B.fruticosa.The fine strain producing antibiotic was screened and the orthogonal designing methods were used for the optimal cultural conditions and medium compositions.The culture of the endophytic fungus BP103381 from B.platyphylla showed strong antimicrobial activity,and the strain was identified as Phomopsis sp..The results showed that the cultural conditions and medium compositions were good for production of antimicrobial activity substance,in the modified Czapek medium（40 g/L sucrose,3 g/L NaNO3,1 g/L MgSO4） and in pH 6.5,28 ℃ for 9 d.The antimicrobial activity substance from BP103381 had good thermal stability,but acid-base changes had great influence on antimicrobial activity of production and the stronger activity was in pH 5.0~7.0.