塔宾曲霉L-27菌株的分离鉴定及其发酵液除草潜力

Isolation and identification of Aspergillus tubingensis L-27 strain and herbicidal potential of its fermentation broth

摘要:

[背景] 微生物源天然产物是新农药研究开发的热点之一。[目的] 从土壤中分离筛选代谢产物具有除草潜力的真菌菌株。[方法] 培养皿滤纸法测定分离菌株发酵液对植物幼苗生长的抑制作用及抑制作用稳定性，显微观察结合rDNA ITS序列分析鉴定菌株。[结果] 在分离的30株土壤真菌中，L-27菌株发酵液对小麦幼苗生长抑制最显著，对根、茎抑制率分别为79.4%、67.3%。基于菌落形态、菌体显微观察和rDNA ITS基因序列分析，分离菌株L-27被鉴定为塔宾曲霉（Aspergillus tubingensis）。进一步测定发现，L-27菌株发酵液完全抑制反枝苋、马齿苋、稗草的幼苗生长，对圆叶牵牛幼苗根、茎的抑制率分别为100%、77.8%。L-27菌株发酵液对小麦幼苗生长的抑制作用表现出良好的热稳定性、酸碱稳定性和紫外光照射稳定性。发酵液在120℃加热20 min，根、茎生长抑制率分别为100%和73.8%；将发酵液调至pH 2.0—12.0并保持1 h，再调回初始pH值，对根、茎生长的抑制率均达100%；发酵液经紫外光照射5—240 min，抑制率分别为100%和84.3%—91.7%。[结论] 分离的塔宾曲霉L-27菌株发酵液具有开发微生物源除草剂的潜力。

Abstract:

[Background] Natural production derived from microorganisms are one of the hot topics in the research and development of new pesticides. [Objective] To isolate and screen soil fungi producing potential herbicidal metabolites. [Methods] Petri dish filter paper culture method was adopted to determine the inhibition effect and stability of fermentation broth on the growth of plant seedlings, and the active strain was identified by microscopic observation and rDNA ITS sequence analysis. [Results] Of 30 fungal strains isolated from soil, the fermentation broth of isolated strain L-27 had significant inhibitory effect on wheat seedling, with inhibition rates 79.4% and 67.3% on root and stem length. Based on colony morphology, micromorphology and rDNA ITS gene sequences analysis, the isolated strain L-27 was identified as Aspergillus tubingensis. Further, strain L-27 fermentation broth completely inhibited seedling growth of Amaranthus retroflexus, Portulaca oleracea, Echinochloa crusgalli and Ipomoea purpurea except for 77.8% reduction of stem length on I. purpurea. The inhibitory effect of strain L-27 fermentation broth on wheat seedling growth had high stability to temperature, pH and UV light radiation, with inhibition rate 100% and 73.8% on root and stem length even heated at 120℃ for 20 min, 100% and 100% at pH 2.0—12.0 for 1 h, and 100% and 84.3%—91.7% under UV light radiation for 5 min to 240 min. [Conclusion] The fermentation broth characteristics of the isolated A. tubingensis L-27 indicated its great potential to develop herbicide.