Biochemical, genetic, and zoosporicidal properties of cyclic lipopeptide surfactants produced by Pseudomonas fluorescens
Biochemical, genetic, and zoosporicidal properties of cyclic lipopeptide surfactants produced by Pseudomonas fluorescens
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DOI：
10.1128/aem.69.12.7161-7172.2003
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发表时间：
2003-12-01
影响因子：
4.4
通讯作者：
Raaijmakers, JM
中科院分区：
文献类型：
--
作者：
de Souza, JT;de Boer, M;Raaijmakers, JM
游动孢子在卵菌等游动孢子真菌侵染动植物宿主中起着重要作用。本研究从小麦根际分离到6株具有杀游动孢子活性的荧光假单胞菌。腐霉、白念珠菌和晚疫霉菌等多种卵菌的游动孢子在6个菌株的细胞悬浮液或培养上清液作用30 S内不动，60 S内裂解，经鉴定为荧光假单胞菌生物群II，代表菌株SS101可使水的表面张力从73 mN m(-1)降至30 mN m(-1)。SS101菌株的细胞悬浮液应用于土壤或风信子鳞茎上，对中间腐霉引起的根腐病有明显的保护作用。菌株SS101的5个Tn5突变体缺乏降低水的表面张力和引起游动孢子溶解的能力。两个缺乏表面活性物质的突变体的遗传特征表明，转座子已整合到多肽合成酶的缩合结构域中。SS101菌株的部分纯化提取物使水的表面张力降至30mN m(-1)，并在25ug ml(-1)时达到临界胶束浓度。反相高效液相色谱分离得到8个不同的组分，其中5个组分具有表面活性，能溶解游动孢子。通过质谱分析和核磁共振分析，确定其主要成分为含有9个氨基酸和10个碳羟基脂肪酸的环状脂肽(1,139 Da)。其他4个杀游动孢子组分与主成分关系密切，分子质量在1111~1169Da之间。
Zoospores play an important role in the infection of plant and animal hosts by oomycetes and other zoosporic fungi. In this study, six fluorescent Pseudomonas isolates with zoosporicidal activities were obtained from the wheat rhizosphere. Zoospores of multiple oomycetes, including Pythium species, Albugo candida, and Phytophthora infestans, were rendered immotile within 30 s of exposure to cell suspensions or cell culture supernatants of the six isolates, and subsequent lysis occurred within 60 s. The representative strain SS101, identified as Pseudomonas fluorescens biovar II, reduced the surface tension of water from 73 to 30 mN m(-1). The application of cell suspensions of strain SS101 to soil or hyacinth bulbs provided significant protection against root rot caused by Pythium intermedium. Five Tn5 mutants of strain SS101 lacked the abilities to reduce the surface tension of water and to cause lysis of zoospores. Genetic characterization of two surfactant-deficient mutants showed that the transposons had integrated into condensation domains of peptide synthetases. A partially purified extract from strain SS101 reduced the surface tension of water to 30 mN m(-1) and reached the critical micelle concentration at 25 mug ml(-1). Reverse-phase high-performance liquid chromatography yielded eight different fractions, five of which had surface activity and caused lysis of zoospores. Mass spectrometry and nuclear magnetic resonance analyses allowed the identification of the main constituent as a cyclic lipopeptide (1,139 Da) containing nine amino acids and a 10-carbon hydroxy fatty acid. The other four zoosporicidal fractions were closely related to the main constituent, with molecular masses ranging from 1,111 to 1,169 Da.