杀线虫海洋细菌G-23的鉴定及培养条件研究

针对危害松属植物的重要病原物松材线虫,本文对采自于青岛近海海域的样品进行细菌分离,得到49株细菌,并采用浸渍法对这些菌株的培养液进行杀线虫活性测定,从中筛选出1株具有较高杀线活性的海洋细菌G-23,将该菌株鉴定为产黑假交替单胞菌(Pseudoalteromonas nigrifaciens),对菌株G-23的培养条件及所产杀线虫活性物质的稳定性进行研究,结果表明,该菌株产杀线活性物质的最佳培养条件为:初始pH8.0,培养温度25℃,菌龄19h,培养时间3d;在海水浓度为100%的Zobell 2216E培养基中生长,有利于活性物质的产生;该菌株产生的杀线虫物质热稳定性较好,既有极性小的物质,也有水溶性物质,在弱碱性(pH8.0)条件下活性较稳定。该研究可为海洋微生物活性物质的开发利用以及松萎蔫病的生物防治提供了理论依据。

Identification and Culture Condition Study of Marine Bacterium G-23 with Nematicidal Activity Against Pine Wood Nematode

Pine wood nematode （PWN）, Bursaphelenchus ：cylophilus, is an important pathogen to conifer trees. In order to screen high nematicidal marine bacteria, forty-nine marine bacterial strains were obtained from the samples collected from the subtidal beds at Qingdao and were assayed in vitro for nematicidal ac- tivity using immersion test. One of these strains, designated as G - 23, which was identified as Pseud- oalteromonas nigrifaciens, exhibited high nematicidal activity. The results from the single-factor experi- ments demonstrated that the optimal cultivation conditions of G - 23 for the production of nematicidal sub- stances were as follows： inoculating 19 h-old culture into Zobell 2216E medium prepared with 100% sea- water, with initial pH 8.0 and cultivating at 25~C for 3 days. In the experiment of stabilitytest, the results indicated that the nematicidal substances produced in the liquid medium by the bacterium G- 23 contained both highly water soluble and low polarity substances which were heat stable, and relatively stable under weakly alkaline （pH8.0） conditions. This study provides theoretical basis for the utilization of marine mi- croorganism resources and the biological control of pine wilt disease caused by PWN.