Characterization of potential chalky soil bacteria isolated from rhizosphere of Acacia spp. growing in Abardae, Maekel Region of Eritrea

The expanding influence of disease-resistant microbes, pollution, and climate change on agriculture, the environment, and public health has increased the interest in soil microorganisms, particularly plant-growth-promoting rhizobacteria (PGPR). In today's world, discovering soil bacteria with potential for biotechnological advancements is highly significant. Therefore, the purpose of the current study was to characterize chalky soil bacteria that were isolated from the rhizosphere of Acacia spp. growing in the Maekel region of Eritrea. In this study, three chalky soil samples were taken from the rhizosphere of Acacia ethibica, Acacia origena, and non-rhizospheric soil. The number of culturable bacteria in the samples was found to be 1.42 x 10¹⁰, 5.35 x 10⁹, and 5.68 x 10⁷ cfu/g, respectively. In total, 80 bacterial strains were isolated, and 10 of them were chosen for further investigation based on their distinct morphology. The cell morphology of the strains was examined using a Nikon Eclipse Ci microscope. The results demonstrated that the aerial mycelium of strain EAE-1 exhibited a novel and previously undescribed organization of spore-bearing hyphae. The antimicrobial activity against phytopathogenic microbes was evaluated. The results revealed that EAE-1, EAE-3, EAE-14, EAE-15, EAE-40, and EAO-24 exhibited wide-ranging antimicrobial effects. Moreover, plant-growth-promoting activity was assessed using various growth parameters. Most of the strains exhibited significant effects on the growth of wheat. However, the bacterial strains EAE-40 and EAO-17 exhibited significant effects on the growth of maize. In conclusion, the current study probably found novel bacterial strains. Future research will be conducted on these strains, with a particular focus on strain EAE-1. Moreover, this study represents the first comprehensive analysis of the microbial composition of Eritrean soil.