Ayyadurai N, Ravindra Naik P, Sreehari Rao M, Sunish Kumar R, Samrat S K, Manohar M, Sakthivel N
Department of Biotechnology, Pondicherry University, Kalapet, Pondicherry, India.
J Appl Microbiol. 2006 May;100(5):926-37. doi: 10.1111/j.1365-2672.2006.02863.x.
Isolation and characterization of a bacterial isolate (strain FP10) from banana rhizosphere with innate potential as fungal antagonist and microbial adjuvant in micropropagation of banana.
Bacterium FP10 was isolated from the banana rhizosphere and identified as Pseudomonas aeruginosa based on phenotypic, biochemical traits and sequence homology of partial 622-bp fragment of 16S ribosomal DNA (rDNA) amplicon, with the ribosomal database sequences. Strain FP10 displayed antibiosis towards fungi causing wilt and root necrosis diseases of banana. Production of plant growth hormone, indole-3-acetic acid (IAA), siderophores and phosphate-solubilizing enzyme in FP10 was determined. Strain FP10 tested negative for hydrogen cyanide, cellulase and pectinase, the deleterious traits for plant growth. Screening of antibiotic genes was carried out by polymerase chain reaction using gene-specific primers. Amplification of a 745-bp DNA fragment confirmed the presence of phlD, which is a key gene involved in the biosynthesis of 2,4-diacetylphloroglucinol (DAPG) in FP10. The antibiotic produced by FP10 was confirmed as DAPG using thin layer chromatography, high performance liquid chromatography and Fourier transform infrared and tested for fungal antibiosis towards banana pathogens. Procedures for encapsulation of banana shoot tips with FP10 are described.
Strain FP10 exhibited broad-spectrum antibiosis towards banana fungi causing wilt and root necrosis. DAPG by FP10 induced bulb formation and lysis of fungal mycelia. Encapsulation of banana shoot tips with FP10 induced higher frequency of germination (plantlet development) than nontreated controls on Murashige and Skoog basal medium. Treatment of banana plants with FP10 enhanced plant height and reduced the vascular discolouration as a result of Fusarium oxysporum f. sp. cubense FOC.
Because of the innate potential of fungal antibiosis by DAPG antibiotic and production of siderophore, plant-growth-promoting IAA and phosphatase, the strain FP10 can be used as biofertilizer as well as a biocontrol agent.
从香蕉根际分离并鉴定一种细菌菌株（FP10），该菌株具有作为香蕉微繁殖中真菌拮抗剂和微生物佐剂的内在潜力。
从香蕉根际分离出细菌FP10，并根据其表型、生化特性以及16S核糖体DNA（rDNA）扩增子622bp部分片段与核糖体数据库序列的序列同源性，鉴定为铜绿假单胞菌。菌株FP10对引起香蕉枯萎病和根坏死病的真菌具有抗菌活性。测定了FP10中植物生长激素吲哚-3-乙酸（IAA）、铁载体和溶磷酶的产生情况。菌株FP10对植物生长有害的性状如氰化氢、纤维素酶和果胶酶检测呈阴性。使用基因特异性引物通过聚合酶链反应对抗生素基因进行筛选。扩增出745bp的DNA片段证实了phlD的存在，phlD是FP10中参与2,4-二乙酰基间苯三酚（DAPG）生物合成的关键基因。使用薄层色谱、高效液相色谱和傅里叶变换红外光谱法确认FP10产生的抗生素为DAPG，并测试其对香蕉病原菌的真菌抗菌活性。描述了用FP10封装香蕉茎尖的方法。
菌株FP10对引起香蕉枯萎病和根坏死的真菌表现出广谱抗菌活性。FP10产生的DAPG诱导球茎形成并使真菌菌丝体裂解。在Murashige和Skoog基本培养基上，用FP10封装香蕉茎尖比未处理的对照诱导出更高的发芽频率（植株发育）。用FP10处理香蕉植株可增加株高，并减少尖孢镰刀菌古巴专化型（FOC）导致的维管束变色。
由于DAPG抗生素具有真菌抗菌的内在潜力以及铁载体、促进植物生长的IAA和磷酸酶的产生，菌株FP10可作为生物肥料和生物防治剂使用。
