杭州地区黄瓜猝倒病菌产嗜铁素拮抗菌的筛选与评价

从杭州地区各蔬菜种植地大量采集土样,采用平板稀释法从中分离纯化得到789个细菌分离物。室内平板对峙法获得对黄瓜猝倒病菌有明显拮抗作用的菌株21个,所占比例为2.67%,其抑菌圈直径为3.1￣16.4mm。再利用选择性培养基法从中筛选得到9株嗜铁素产生菌。最后对黄瓜猝倒病菌产嗜铁素拮抗菌进行评价,结果表明,各菌株产生嗜铁素的能力不同,定性与定量分析结果基本吻合;嗜铁素光吸收特性研究表明,pH直接影响嗜铁素光吸收,过酸过碱的条件光吸收峰偏向短波长,而中性条件下光吸收峰偏向长波长。pH8.3有3个吸收峰,分别在224.0nm,264.0nm和400.0nm附近,并且光吸收峰最大,说明pH8.3较适合试验菌产嗜铁素;嗜铁素产生菌对黄瓜生长的初步研究表明,其对黄瓜生长有3种作用即:促进、抑制和影响不大。

Screening and Evaluation of Antagonistic Bacteria Producing Siderophore Against Pathogen of Cucumber Damping-off in Zhejiang District

Using plate dilution method, seven hundred and eighty-nine strains were isolated and purified from the diffrent vegetable soil samples collected from the suburban districts. By pairing culture, 12 strains had apparent antagonistic effect to Pythium ultimum, ca. 2.67% of all tested strains showed antagonism, whose radius of suppression cycles was between 3.1~16.4 mm. By selected medium method, nine strains producing siderophore were obtained. Qualitative and quantitative analysis showed that different strains had different ability producing siderophore, but the result of two methods was consistant. pH value had a direct effect on absorbance of siderophore, absorbance declined to shortwave under excessive acidic and alkaline pH conditions, while to longwave under neutral pH conditions. It had three absorbance apexes and got to maximun, which were 224.0 nm, 264.0 nm and 400.0 nm, respectively under pH8.3. Effect of bacteria producing siderophore on cucumber growth showed three actions,which were promotion, inhibition and no action, respectively.