细菌XS-JS3对松材线虫杀线活性的测定

A study of the nematicidal activity of bacterium XS-JS3 to Bursaphelenchus xylophilus

细菌XS-JS3是一种新发现的对松材线虫(Bursaphelenchus xylophilus)具有较高杀线活性的细菌,试验比较了细菌XS-JS3培养液、细菌培养液滤液及含菌体水溶液对松材线虫的杀线活性,结果发现细菌菌体本身对松材线虫无杀线活性,杀线活性物质存在于细菌的培养液滤液中。通过对该细菌培养液滤液对松材线虫致死过程的观察发现:松材线虫接触该细菌培养液滤液30min后就表现为行动迟缓;在5h后所有虫体均不活动,针刺无反应;24h后部分僵直虫体出现局部膨大,且膨大部位出现体液外渗而虫体最终被消解。对不同培养时间的细菌XS-JS3滤液杀线活性的比较试验表明:该细菌分泌的杀线物质在10d内随培养时间的延长而含量增加,杀线活性逐渐提高,不同培养时间下滤液的杀线活性差异明显;但培养15d后,稀释10倍的滤液对松材线虫杀线活性比培养10d时同样滤液的杀线活性则略有下降,但差异不明显,因此获得该细菌分泌的杀线物质较理想的培养时间为10d。将细菌XS-JS3培养液滤液进行不同温度的热处理后测定对松材线虫的杀线活性,结果表明引起松材线虫死亡和消解的物质是两个不同物质,存在于培养液滤液中的对松材线虫有杀线活性的物质是热稳定的,而引起松材线虫虫体消解的物质是热不稳定的。

The nematicidal activity of Bacterium XS - JS3 cultured filtrate was firstly reported in this paper. In this experiment the nematodes activity of the bacteria cultured broth, filtrate and bacteria solution to Bursaphelenchus xylophilus have been compared respectively. The result indicated that the bacteria did not show any nematicidal activity to B. xylophilus. The pathogenic process of the filtrate of culture broth of XS - JS3 to B. xylophilus was observed. It was found that the body cuticle of B. xylophilus was broken up. The body fluid flowed from the body and was decomposed after the nematodes contacted the filtrate more than 24 h. The phenomena showed that some kinds of nematode toxins may be produced by Bacterium XS - JS3 when it was cultured on a rotary shaker. The nematicidal activity increased as the culture time went on. After the bacteria have been cultured on the rotary shaker for 10 days, the highest nematicidal activity was attained. So the fittest culture time of the bacteria was possibly 10 days. In the experiment of heat stability, the result indicated that there were two kinds of matters produced in the cultural filtrate by the bacterium. One matter had nematicidal activity and was stable to heat. The other one could decompose the nematode body and was not stable to the heat.