Laboratory of Phytopathology, Wageningen University, The Netherlands.
J Appl Microbiol. 2009 Aug;107(2):546-56. doi: 10.1111/j.1365-2672.2009.04244.x. Epub 2009 Mar 19.
Plant growth-promoting Pseudomonas putida strain 267, originally isolated from the rhizosphere of black pepper, produces biosurfactants that cause lysis of zoospores of the oomycete pathogen Phytophthora capsici. The biosurfactants were characterized, the biosynthesis gene(s) partially identified, and their role in control of Phytophthora damping-off of cucumber evaluated.
The biosurfactants were shown to lyse zoospores of Phy. capsici and inhibit growth of the fungal pathogens Botrytis cinerea and Rhizoctonia solani. In vitro assays further showed that the biosurfactants of strain 267 are essential in swarming motility and biofilm formation. In spite of the zoosporicidal activity, the biosurfactants did not play a significant role in control of Phytophthora damping-off of cucumber, since both wild type strain 267 and its biosurfactant-deficient mutant were equally effective, and addition of the biosurfactants did not provide control. Genetic characterization revealed that surfactant biosynthesis in strain 267 is governed by homologues of PsoA and PsoB, two nonribosomal peptide synthetases involved in production of the cyclic lipopeptides (CLPs) putisolvin I and II. The structural relatedness of the biosurfactants of strain 267 to putisolvins I and II was supported by LC-MS and MS-MS analyses.
The biosurfactants produced by Ps. putida 267 were identified as putisolvin-like CLPs; they are essential in swarming motility and biofilm formation, and have zoosporicidal and antifungal activities. Strain 267 provides excellent biocontrol activity against Phytophthora damping-off of cucumber, but the lipopeptide surfactants are not involved in disease suppression.
Pseudomonas putida 267 suppresses Phy. capsici damping-off of cucumber and provides a potential supplementary strategy to control this economically important oomycete pathogen. The putisolvin-like biosurfactants exhibit zoosporicidal and antifungal activities, yet they do not contribute to biocontrol of Phy. capsici and colonization of cucumber roots by Ps. putida 267. These results suggest that Ps. putida 267 employs other, yet uncharacterized, mechanisms to suppress Phy. capsici.
最初从黑胡椒根际分离到的植物促生假单胞菌 267 菌株产生生物表面活性剂，导致卵菌病原体辣椒疫霉游动孢子裂解。对生物表面活性剂进行了表征，部分鉴定了生物合成基因，并评估了其在防治黄瓜立枯病中的作用。
证明生物表面活性剂裂解辣椒疫霉游动孢子并抑制真菌病原体葡萄孢和立枯丝核菌的生长。体外试验进一步表明，267 菌株的生物表面活性剂在群集运动和生物膜形成中是必需的。尽管具有杀游动孢子活性，但生物表面活性剂在防治黄瓜立枯病中并没有发挥重要作用，因为野生型菌株 267 及其生物表面活性剂缺陷突变体同样有效，并且添加生物表面活性剂不能提供防治效果。遗传特征表明，267 菌株中表面活性剂的生物合成受 PsoA 和 PsoB 同源物的控制，PsoA 和 PsoB 是两种非核糖体肽合成酶，参与环状脂肽（CLPs）putisolvin I 和 II 的产生。267 菌株生物表面活性剂与 putisolvin I 和 II 的结构相关性得到了 LC-MS 和 MS-MS 分析的支持。
由 Ps. putida 267 产生的生物表面活性剂被鉴定为 putisolvin 样 CLPs；它们在群集运动和生物膜形成中是必需的，具有杀游动孢子和抗真菌活性。菌株 267 对黄瓜疫霉立枯病具有极好的生物防治活性，但脂肽表面活性剂不参与疾病抑制。
假单胞菌 267 抑制辣椒疫霉引起的黄瓜猝倒病，并为防治这种经济上重要的卵菌病原体提供了一种潜在的补充策略。putisolvin 样生物表面活性剂具有杀游动孢子和抗真菌活性，但它们不能促进 Ps. putida 267 对 Phy. capsici 的生物防治和对黄瓜根系的定殖。这些结果表明，Ps. putida 267 采用其他尚未表征的机制来抑制 Phy. capsici。
