具铁载体活性病原细菌的筛选及铁摄取干预对其生长影响

绝大多数病原菌可分泌铁载体,利用螯合性铁载体及病原菌对Fe~(3+)的竞争可实现病害的有效防控。从植物病原菌中筛选高产铁载体的优势菌株,并基于EDTA对铁离子的强螯合性,可为病害防控提供新的方法。本研究采用CAS检测法和光吸收法对42株供试植物病原菌株进行定性、定量筛选及铁载体类型的初步鉴定,依据菌株形态电镜观察和分子生物学技术对优势菌株进行分类鉴定,并基于微量稀释法测定EDTA对优势菌株的最低抑菌浓度。经定性、定量筛选,确定7株供试细菌为高产铁载体优势菌株,分泌铁载体类型为儿茶酚型和异羟肟酸型;根据形态特征观察和分子生物学鉴定,菌株TZT-057和TZT-058与恶臭假单胞菌Pseudomonas putida的一致性最高,TZT-059、TZT-063和TZT-064与肺炎克雷伯氏菌Klebsiella pneumoniae的一致性最高,TZT-062、TZT-073分别与鲁氏不动杆菌Acinetobacter lwoffii、迪克氏菌Dickeya zeae的一致性最高。根据微量稀释法抑菌活性测定结果可知,EDTA对菌株TZT-058、TZT-073的抑菌效果较好,抑菌率分别为85.16%、80.08%,表明强螯合剂EDTA能有效干预病原细菌对铁元素的摄取过程,进而影响其生长繁殖。

Screening of the pathogenic bacteria with siderophore-producing activity and the effect of intervention in iron uptake on its growth

Most pathogenic microorganisms have the function of secreting siderophore, and the competition between sorghum siderophore and pathogens against Fe3+ can be used to effectively prevent and control diseases. The dominant strains producing high-yield siderophore were screened from plant pathogens, and based on the strong chelating property of EDTA to iron, it could provide a new method for the control of plant diseases. In this study, we qualitatively and quantitatively screen the pathogenic strains of different host plants and preliminarily identified the siderophore types by using the CAS method and light absorption method. Meanwhile, the biological identification of the dominant strains was performed by using the electron microscopy and 16S rDNA sequence. The minimum inhibitory concentration of EDTA against dominant strains was determined based on the microdilution method. The results showed that there were 7 strains that were identified as high siderophore-producing dominant strains from the test bacteria through qualitative and quantitative screening, and the types of secretory siderophore were catecholates and hydroxamates. Base on the morphological characteristics and molecular identification, the strains TZT-057 and TZT-058 shared similarity with Pseudomonas putida; the strains TZT-059, TZT-063 and TZT-064 were very similar to Klebsiella pneumoniae; the strain TZT-062 was analogous to Acinetobacter lwoffii, and strain TZT-073 resembled Dickeya zeae. According to the microbial dilution assay, EDTA had better antibacterial activity against strains TZT-058 and TZT-073, and the inhibition rates were 85.16% and 80.08%, respectively. The results suggested that EDTA could effectively affect the uptake process of iron by pathogenic bacteria, and affect its growth and reproduction.