Gul Karim, Khan Raham Sher, Iqbal Aneela, Ullah Atta, Shah Syed Muhammad Shafi, Hussain Anwar, Law Douglas, Ahmad Ayaz, Khan Salimullah
Department of Biotechnology, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan.
Department of Botany, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan.
Folia Microbiol (Praha). 2025 Aug 11. doi: 10.1007/s12223-025-01312-1.
Bacterial endophytes are a key part of the plant microbiome that influence developmental processes via different mechanisms. One of the known mechanisms is the production of exopolysaccharides (EPS) that are responsible for the response towards stresses and plant-bacterial interactions. In the current experiment, we isolated 42 strains of bacterial endophytes from the sterilized parts of Moringa oleifera plant and screened them for the production of EPS. Out of the 42, only three isolates; KR-27, KL-4, and KS-7 produced a significant amount of EPS. All these isolates showed in vitro antagonistic activities against phytopathogenic fungi and bacteria. These antagonistic endophytic isolates, KR-27, KL-4, and KS-7 were identified as Serratia marcescens, Klebsiella aerogenes, and Lelliottia amnigena, respectively based on 16 s RNA gene ribotyping. The selected bacterial strains were screened out for phytohormones and secondary metabolites production and all the identified strains produced significant amount of various phytohormones such as indole acetic acid (IAA), gibberellic acid (GA), and salicylic acid (SA). In addition, the identified strains produced the antioxidant compounds like siderophores, phenolics, and flavonoids. The phosphate solubilization ability of all the strains was ascertained and found highest for KR-27 (30.46 ± 0.82 μg/mL), followed by KS-7 (18.30 ± 0.54 μg/mL) and KL-4 (17.36 ± 0.68 μg/mL). Unlike previous research, which primarily focused on the nutritional and medicinal properties of M. oleifera, this research uncovers the new aspect by exploring the biotechnologically important bacterial flora of this miracle tree. In conclusion we isolated three novel bacterial endophytic strains with the ability to produce bioactive compounds for plant and antimicrobial activity against phytopathogens for the first time which can replace the synthetic fertilizers and pesticides in future sustainable agriculture practices.
细菌内生菌是植物微生物群的关键组成部分，通过不同机制影响植物发育过程。已知机制之一是产生胞外多糖（EPS），其负责植物对胁迫的响应以及植物与细菌的相互作用。在当前实验中，我们从辣木植物的无菌部位分离出42株细菌内生菌，并筛选它们产生EPS的能力。在这42株中，只有三株分离物；KR - 27、KL - 4和KS - 7产生了大量EPS。所有这些分离物均对植物病原真菌和细菌表现出体外拮抗活性。基于16 s RNA基因核糖体分型，这些拮抗内生菌分离物KR - 27、KL - 4和KS - 7分别被鉴定为粘质沙雷氏菌、产气克雷伯菌和水生拉恩菌。对所选细菌菌株进行植物激素和次生代谢产物生产的筛选，所有鉴定出的菌株都产生了大量的各种植物激素，如吲哚乙酸（IAA）、赤霉素（GA）和水杨酸（SA）。此外，鉴定出的菌株还产生了铁载体、酚类和黄酮类等抗氧化化合物。测定了所有菌株的解磷能力，发现KR - 27最高（30.46±0.82μg/mL），其次是KS - 7（18.30±0.54μg/mL）和KL - 4（17.36±0.68μg/mL）。与以往主要关注辣木营养和药用特性的研究不同，本研究通过探索这一神奇树木具有生物技术重要性的细菌菌群，揭示了新的方面。总之，我们首次分离出三株新型细菌内生菌株，它们能够产生生物活性化合物，对植物具有活性并对植物病原体具有抗菌活性，有望在未来可持续农业实践中替代合成肥料和农药。
