使君子内生真菌杀线虫活性菌株的筛选及其培养条件的研究

以松材线虫Bursaphelenchus xylophilus为靶标,从249株使君子Quisqualis indica内生真菌中筛选到活性较强的菌株10个,其中菌株FDYS-1活性最高,培养滤液对线虫的致死率达99%;培养滤液杀线活性热稳定性好,121℃处理20min仍不失活,而且活性物质的产生能力遗传稳定,连续继代6代后致死率仍达90.43%。单因子试验和正交试验结果表明,在PD培养液、初始pH5~8、150r/min、装液量100ml/500ml、接种7块菌饼（φ=5mm）的条件下培养3d,菌株FDYS-1生长最好,滤液杀线活性最强,稀释3倍后对松材线虫的致死率仍高达96.45%。正交试验极差分析表明,培养时间是影响培养滤液杀线活性的关键因子。形态学观察和ITS序列分析初步确定菌株FDYS-1为炭角菌属Xylaria sp.真菌。

Screening of Nematicidal Isolates from the Endophytic Fungi of Quisqualis indica and Optimization of Culture Conditions for the Isolate

Toxicity of the isolated fungal endophytes from Quisqualis indica to Bursaphelenchus xylophilus was evaluated via their culture filtrates.The result showed that 10 of 249 isolates were toxic to the nematode.Strain FDYS-1 exhibited a mortality of 99%.It was observed that FDYS-1 was hereditarily stable,which could keep the bio-activity after 6 successive transfers,and its active metabolite was heat-stable,which could resist to 121℃ for 20 min.Single-factor and orthogonal experiments indicated that 100 ml potato dextrose liquid（PD,pH 5-8） and 7 pieces of mycelium mats in diameter 5 mm in a 500 ml conical flask were optimal for FDYS-1 to grow when cultured at 26℃ under 150 r/min for 3 d,and its culture filtrate exhibited the strongest nematicidal activity,leading to the mortality of nematodes up to 96.45% even though it was treble-diluted.The time period of culture was found to be crucial to its nematicidal activity.According to its morphological characteristics and ITS sequence analysis,the strain FDYS-1 was identified to be Xylaria sp..