松材线虫携带细菌的鉴定和毒性研究

从松材线虫病致死的松材木质部和松材线虫体表分离到3个出现频率较高的细菌菌株，菌株Nji、Njt和Njw。经鉴定3种细菌分别为荧光假单胞菌I型（Pseudomonas fluorescens biotype I)荧光假单胞菌Ⅱ型（Pseudomonas fluorescens biotype Ⅱ）和泛菌属某种（Pantoea sp.)。用牛肉膏蛋白胨液体培养基振荡培养细菌，培养液直接处理黑松愈伤组织，测定各细菌的产毒能力。与对照（空白培养液）相比，3种细菌的培养原液都可对黑松愈伤组织产生明显影响，其中菌株Nih和菌株Njt可以在2d内使愈伤组织明显变色，菌株Njw处理变色较慢。表明菌株Nij和Njt培养液内有大量致萎毒性物质存在。

Studies on Identification and Toxicity of Bacteria Carried by Pine Wood Nematodes

Three bacterium strains with a high frequency,viz.Njh,Njt and Njw,have been isolated from the xylem of a wilted black pine( Pinus thuntergii )tree caused by pine wood nematodes and from the surface of the nematodes.These bacteria have been identified as Pseudomonas fluorescens biotype I, Pseudomonas fluorescens biotype II and a species of the genus Pantoea respectively.Bacteria were cultured in liquid media through rocking.The liquid was directly used in the treatment of the callus of black pine and ability of each kind of bacterium to produce toxin was measured.As compared with control(viz.blank liquid media),the original culture liquid from three kinds of bacteria had an obvious effect on wilting of the materials used in bioassay.Strains Njh and Njt were stronger than Njw in pathogenicity.Part of calluses turn yellow browning 48 hours after the original liquid containing toxin was added.5 days after bioassay all of the callus masses were black browning and died on account of the original liquid containing the toxin from strains Njh and Njt added.There was no big change in color of the callus to which the liquid containing the toxin from the strain Njw was added,but it's darker than the control.It has been proved that there was a great quantity of wilt related toxins existing in strains Njh and Njt