Ajdig Mohammed, Mbarki Ahlam, Chouati Taha, Rached Bahia, Gardoul Mouhcine, Filali-Maltouf Abdelkarim, Talbi Chouhra, Fahime Elmostafa El, Melloul Marouane
Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnology, Biodiversity and Environment, Faculty of Sciences, Mohammed V University, Rabat, Morocco.
Laboratory of Biological Analysis, CCMM - Centre for Scientific and Technical Research (CNRST), Rabat, Morocco.
World J Microbiol Biotechnol. 2025 Jul 28;41(8):276. doi: 10.1007/s11274-025-04488-3.
Abiotic and biotic stresses increasingly threaten plant health and productivity, causing substantial yield losses in vital crops. In this study, 99 rhizobacteria isolated from Moroccan olive rhizospheres, OM-41 was selected as the most potent strain, exhibiting exceptional drought tolerance (thriving at Aw 0.859), thermotolerance (up to 55 °C), and halotolerance (15% NaCl), alongside plant growth-promoting (PGP) traits such as phosphate solubilization, indole-acetic acid (IAA), gibberellic acid, siderophore production, and hydrolytic enzyme secretion. The strain suppressed V. dahliae via diffusible and volatile antifungal compounds, achieving 76% and 69% inhibition rates, respectively. Whole-genome sequencing revealed a 4.2 Mbp genome (43.5% GC content) with 4362 protein-coding genes. Phylogenetic analyses confirmed its classification as B. halotolerans. Genomic annotation identified 11 secondary metabolite clusters and stress-related genes, including those linked to phosphate solubilization (phy, pho, pst family), IAA synthesis (dhaS, trp operon), siderophores (dhb cluster), nitrogen fixation (nif, suf, urt genes), ammonia production (gudB, nasD/E), biofilm formation (tasA, bsl genes), antifungal volatiles (alsD, ilv operon), hydrolytic enzymes (e.g., amyE, eglS), and vitamin biosynthesis (thiamine/riboflavin operons). Pangenome analysis of 79 B. halotolerans strains highlighted an open pangenome with 12,679 total genes (2270 core, 2382 accessory and 8027 unique); OM-41 harbored 98 unique genes. These findings underscore potential of OM-41 as a biofertilizer and biocontrol agent, leveraging antibiosis, resource competition, and plant defense induction to mitigate pathogens and abiotic stresses. Up to our knowledge, this is the first work that evaluates the pangenome features of B. halotolerans, offering insights into its genomic plasticity and adaptive traits. The strain's multifunctional PGP capabilities and stress resilience position it as a promising solution for sustainable agriculture in challenging environments.
非生物和生物胁迫日益威胁着植物健康和生产力，导致重要作物大幅减产。在本研究中，从摩洛哥橄榄根际分离出99株根际细菌，OM - 41被选为最具潜力的菌株，它表现出卓越的耐旱性（在水活度0.859时生长良好）、耐热性（高达55℃）和耐盐性（15% NaCl），同时还具有促进植物生长（PGP）的特性，如溶解磷酸盐、产生吲哚 - 乙酸（IAA）、赤霉素、铁载体以及分泌水解酶。该菌株通过可扩散和挥发性抗真菌化合物抑制大丽轮枝菌，抑制率分别达到76%和69%。全基因组测序显示其基因组大小为4.2 Mbp（GC含量为43.5%），有4362个蛋白质编码基因。系统发育分析证实其属于嗜盐芽孢杆菌。基因组注释鉴定出11个次生代谢物簇和与胁迫相关的基因，包括与磷酸盐溶解（phy、pho、pst家族）、IAA合成（dhaS、色氨酸操纵子）、铁载体（dhb簇）、固氮（nif、suf、urt基因）、氨产生（gudB、nasD/E）、生物膜形成（tasA、bsl基因）、抗真菌挥发物（alsD、ilv操纵子）、水解酶（如amyE、eglS）以及维生素生物合成（硫胺素/核黄素操纵子）相关的基因。对79株嗜盐芽孢杆菌菌株的泛基因组分析突出了一个开放的泛基因组，共有12,679个基因（2270个核心基因、2382个辅助基因和8027个独特基因）；OM - 41含有98个独特基因。这些发现强调了OM - 41作为生物肥料和生物防治剂的潜力，它利用抗菌作用、资源竞争和诱导植物防御来减轻病原体和非生物胁迫。据我们所知，这是第一项评估嗜盐芽孢杆菌泛基因组特征的工作，为其基因组可塑性和适应性状提供了见解。该菌株的多功能PGP能力和胁迫恢复力使其成为具有挑战性环境中可持续农业的一个有前景的解决方案。
