Jasim B, Mathew J, Radhakrishnan E K
School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, India.
J Appl Microbiol. 2016 Oct;121(4):1079-94. doi: 10.1111/jam.13214. Epub 2016 Aug 9.
The study mainly aimed the isolation and characterization of plant probiotic endophytic bacteria from Capsicum annuum to explore its multipotent agricultural applications.
Endophytic bacteria were isolated from the surface sterilized fruit tissue. The isolates were then subjected to PCR-based screening for the presence of potential biosynthetic gene clusters. The PCR positive isolate was then analysed for its inhibitory effect towards fungal and bacterial pathogens. The compounds responsible for the antimicrobial activity was purified from large scale culture and subjected to identification by LC-MS/MS. The ability of the selected isolate in plant growth enhancement was also done using Vigna radiata seedlings.
In this study, an endophytic bacterium isolated from C. annuum was found to have the phenotypic and genetic basis for broad antimicrobial property. PCR-based sequence analysis has resulted in the identification of nonribosomal peptide synthases, PKS Type I, Iturin, surfactin, DAPG and gacA genes in the selected isolate CaB 5. The bioactivity-guided fractionation using column and HPLC purification of active fraction followed by LC-MS/MS analysis has proved the presence of surfactin derivatives (M+H(+) - 1008 & 1036) and iturin (M+H(+) - 1058) as the basis of antimicrobial activity of CaB 5. The isolate was identified as a novel Bacillus sp. because of its low (76%) identity to the reported sequences.
Endophytes are considered to have the genetic basis for a diverse array of bioactive metabolites which can have significant applications in both pharmaceutical industry and agriculture. The identification of CaB 5 with broad bioactivity and excellent plant growth enhancement on taxonomically distinct plant species as explained in current study and our previous reports highlights its plant probiotic applicability. This proves the potential of the isolate obtained in the study to be an excellent plant probiotic.
本研究主要旨在从辣椒中分离和鉴定植物益生菌内生细菌，以探索其在农业中的多种应用潜力。
从表面消毒的果实组织中分离内生细菌。然后对分离株进行基于PCR的筛选，以检测潜在生物合成基因簇的存在。对PCR阳性分离株进行抗真菌和细菌病原体的抑制作用分析。从大规模培养物中纯化负责抗菌活性的化合物，并通过LC-MS/MS进行鉴定。还使用绿豆幼苗研究了所选分离株促进植物生长的能力。
在本研究中，从辣椒中分离出的一种内生细菌被发现具有广泛抗菌特性的表型和遗传基础。基于PCR的序列分析已在所选分离株CaB 5中鉴定出非核糖体肽合成酶、I型聚酮合酶、伊枯草菌素、表面活性素、2,4-二乙酰基间苯三酚和gacA基因。通过柱色谱和高效液相色谱对活性馏分进行生物活性导向分级分离，随后进行LC-MS/MS分析，证明存在表面活性素衍生物（M+H(+) - 1008和1036）和伊枯草菌素（M+H(+) - 1058），这是CaB 5抗菌活性的基础。该分离株被鉴定为一种新型芽孢杆菌属，因为它与已报道序列的同源性较低（76%）。
内生菌被认为具有产生多种生物活性代谢物的遗传基础，这些代谢物在制药工业和农业中都有重要应用。如本研究及我们之前的报告所述，鉴定出具有广泛生物活性且能显著促进不同分类植物物种生长的CaB 5，突出了其作为植物益生菌的适用性。这证明了本研究中获得的分离株具有成为优良植物益生菌的潜力。
