de Oliveira Admilton G, Spago Flavia R, Simionato Ane S, Navarro Miguel O P, da Silva Caroline S, Barazetti André R, Cely Martha V T, Tischer Cesar A, San Martin Juca A B, de Jesus Andrade Célia G T, Novello Cláudio R, Mello João C P, Andrade Galdino
Laboratório de Ecologia Microbiana, Departamento de Microbiologia, Universidade Estadual de Londrina Londrina, Brazil.
Laboratório de Espectroscopia, Departamento de Bioquímica e Biotecnologia, Universidade Estadual de Londrina Londrina, Brazil.
Front Microbiol. 2016 Feb 9;7:113. doi: 10.3389/fmicb.2016.00113. eCollection 2016.
Citrus canker is a very destructive disease of citrus species. The challenge is to find new compounds that show strong antibiotic activity and low toxicity to plants and the environment. The objectives of the present study were (1) to extract, purify and evaluate the secondary metabolites with antibiotic activity produced by Pseudomonas aeruginosa LV strain in vitro against Xanthomonas citri subsp. citri (strain 306), (2) to determine the potential of semi-purified secondary metabolites in foliar application to control citrus canker under greenhouse conditions, and (3) to identify antibiotic activity in orange leaf mesophyll infected with strain 306, by electron microscopy. Two pure bioactive compounds were isolated, an organocopper antibiotic compound (OAC) and phenazine-1-carboxamide. Phenazine-1-carboxamide did not show any antibiotic activity under the experimental conditions used in this study. The OAC showed a high level of antibiotic activity with a minimum inhibitory concentration of 0.12 μg mL(-1). In greenhouse tests for control of citrus canker in orange trees, the semi-purified fraction F3d reduced lesion formation by about 97%. The concentration used was 500 times lower than that for the recommended commercial copper-based product. Electron microscopy showed that F3d altered the exopolysaccharide matrix and caused cell lysis of the pathogen inside the citrus canker lesions. These results suggest that secondary metabolites produced by inducing P. aeruginosa LV strain have a high potential to be used as a bioproduct to control citrus canker.
柑橘溃疡病是柑橘类植物的一种极具破坏性的病害。面临的挑战是找到对植物和环境具有强抗生素活性且低毒性的新化合物。本研究的目的是：（1）提取、纯化并评估铜绿假单胞菌LV菌株体外产生的对柑橘溃疡病菌（菌株306）具有抗生素活性的次生代谢产物；（2）确定半纯化次生代谢产物在温室条件下叶面喷施防治柑橘溃疡病的潜力；（3）通过电子显微镜鉴定感染306菌株的橙叶叶肉中的抗生素活性。分离出两种纯生物活性化合物，一种有机铜抗生素化合物（OAC）和吩嗪-1-甲酰胺。在本研究使用的实验条件下，吩嗪-1-甲酰胺未表现出任何抗生素活性。OAC表现出高水平的抗生素活性，最低抑菌浓度为0.12μg mL⁻¹。在温室中对橙子树柑橘溃疡病防治试验中，半纯化组分F3d使病斑形成减少了约97%。使用的浓度比推荐的市售铜基产品低500倍。电子显微镜显示F3d改变了胞外多糖基质并导致柑橘溃疡病斑内病原体的细胞裂解。这些结果表明，诱导铜绿假单胞菌LV菌株产生的次生代谢产物具有很高的潜力可作为生物制品用于防治柑橘溃疡病。
