Jasim B, Sreelakshmi K S, Mathew Jyothis, Radhakrishnan E K
School of Biosciences, Mahatma Gandhi University, PD Hills (PO), Kottayam, Kerala, 686 560, India.
School of Biotechnology, Amrita Vishwa Vidhyapeetham, Clapppana, Kollam, Kerala, 690 525, India.
Microb Ecol. 2016 Jul;72(1):106-119. doi: 10.1007/s00248-016-0753-5. Epub 2016 Mar 28.
Endophytic microorganisms which are ubiquitously present in plants may colonize intracellularly or intercellularly without causing any diseases. By living within the unique chemical environment of a host plant, they produce a vast array of compounds with a wide range of biological activities. Because of this, natural products of endophytic origin have been exploited for antimicrobial, antiviral, anticancer, and antioxidant properties. Also, they can be considered to function as an efficient microbial barrier to protect plants from various pathogens. In the present study, endophytic bacterium BmB 9 with antifungal and antibacterial activity isolated from the stem tissue of Bacopa monnieri was studied for the molecular and chemical basis of its activity. PCR-based genome mining for various biosynthetic gene clusters proved the presence of surfactin, iturin, and type I polyketide synthase (PKS) genes in the isolate. The LC-MS/MS based analysis of the extract further confirmed the production of surfactin derivatives (M + H(+)-1008.6602, 1022.6755), iturin (M + H(+)-1043.5697), and fengycin (M + H(+)-1491.8195, 1477.8055) by the selected bacterial isolate. The 16S rDNA sequence similarity based analysis identified the isolate BmB 9 as Bacillus sp. with 100 % identity to Bacillus sp. LCF1 (KP257289).
植物中普遍存在的内生微生物可以在细胞内或细胞间定殖而不引起任何疾病。通过生活在宿主植物独特的化学环境中，它们产生了大量具有广泛生物活性的化合物。因此，内生来源的天然产物已被开发用于抗菌、抗病毒、抗癌和抗氧化特性。此外，它们可以被认为起到了有效的微生物屏障作用，保护植物免受各种病原体的侵害。在本研究中，对从假马齿苋茎组织中分离出的具有抗真菌和抗菌活性的内生细菌BmB 9的活性分子和化学基础进行了研究。基于PCR的各种生物合成基因簇基因组挖掘证明该分离株中存在表面活性素、伊枯草菌素和I型聚酮合酶（PKS）基因。提取物的基于LC-MS/MS的分析进一步证实了所选细菌分离株产生了表面活性素衍生物（M + H(+)-1008.6602，1022.6755）、伊枯草菌素（M + H(+)-1043.5697）和丰原素（M + H(+)-1491.8195，1477.8055）。基于16S rDNA序列相似性的分析将分离株BmB 9鉴定为芽孢杆菌属，与芽孢杆菌属LCF1（KP257289）具有100%的同一性。
