松材线虫生防细菌的筛选、鉴定及其毒性因子的初步研究

从河南南阳不同农田的植物根部采取土壤样本,共分离获得了198株细菌。通过毒性测试和平板生测从中筛选出松材线虫生防细菌6株,其中NS-3菌株对松材线虫的杀灭活性最高。结合该菌株的形态学、生理学特征及16S rDNA序列分析等结果将该菌株归为芽孢杆菌属,命名为Bacillus sp.strain NS-3。将该细菌液体培养的上清液和上清蛋白粗提物分别处理松材线虫48h后线虫的死亡率分别达到50%和100%;线虫死亡后虫体消解。然而,细菌的上清蛋白粗提物经煮沸变性后,基本丧失了对松材线虫的侵染活性,结果显示细菌Bacillus sp.strain NS-3的杀线虫活性物质主要要存在于细菌培养上清液中,并且为热不稳定性物质。

Screening,Identification and Virulence Factor Determination of the Bacteria with Nematicidal Activity to Bursaphelenchus xylophilus

One hundred and ninety eight bacteria were isolated and tested for their nematicidal activity from the soil in Nanyang, Henan Province, China. Six strains which had nematicidal activity to Bursaphelenchus xylophilus were found. A bacterium, named Bacillus sp. strain NS-3, showed the highest nematicidal activity to B xylophilus. The bacterium was classified by phenotypic and genotypic characteristics, which belonged to Bacillus genus. The culture supernatant and the crude extracellular protein extract from the strain NS-3 separately killed 50 % and 100 % of the tested nematodes (B. xylophilus) within 48 h, which suggested their high toxic activity toward the nematodes. Most of the dead nematodes were degraded and only minor fragments were left. However, the crude protein extract lost nematicidal activity after boiled, which showed the namaticidal materials produced in the cultural filtrate by the bacterium was not stable to the heat.