Survey of Microbes Colonizing the Root System of Some Growing Plants on Uhud Mountain in Almadinah Almunawwarah

Plant-microbe associations are crucial in rhizosphere ecosystem processes, as positive interactions between plants, mycorrhizal fungi, and plant-growth-promoting rhizobacteria (PGPR) increase crop yield and serve as natural alternatives to chemical pesticides for controlling plant diseases. This study aimed to isolate microbes from three plants: Solenostemma argel, Heliotropium arbainense, and Suaeda vermiculate from Uhud Mountain in Al-Madinah Al-Munawara. Most isolates showed promising results for PGP traits under in vitro conditions, both culturally and biochemically. Bacterial isolates belonged to two phyla, Firmicutes and Actinomycetota, while fungal strains belonged to three phyla: Ascomycota, Deuteromycota, and Zygomycota. The efficiency of isolated microbes in producing antimicrobial agents against pathogenic microbes was assessed by measuring their zone of inhibition using agar plug diffusion and agar-well diffusion methods. Results showed that the maximum zone of inhibition was noted in Bacillus isolate C13 against Penicillium (30.3 ± 0.6 mm) in primary screening, while isolate C8 (42.7 ± 8.0 mm) was the most active against Aspergillus in secondary screening. Evaluating fungal isolates' antagonistic activity revealed the highest activity for isolate A2 (76.7 ± 10.4). This study demonstrated that employing microbes as biological control factors against plant pathogens could be an effective strategy for numerous agricultural advancements.