Soil Bacteria from the Namib Desert: Insights into Plant Growth Promotion and Osmotolerance in a Hyper-Arid Environment

Tiago Lopes, Jacinta Santos, Diana Matos, Carina Sá, Diogo Pina, Ricardo Pinto, Paulo Cardoso and Etelvina Figueira ()
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Tiago Lopes: Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
Jacinta Santos: Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
Diana Matos: Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
Carina Sá: Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
Diogo Pina: Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
Ricardo Pinto: Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
Paulo Cardoso: Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
Etelvina Figueira: Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal

Land, 2024, vol. 13, issue 10, 1-16

Abstract: The Namib Desert is characterized by a number of abiotic stresses, including high temperature, high salinity, osmotic pressure, alkaline pH, and limited water availability. In such environments, dry soils typically exhibit a low water potential, scarce nutrients, and high concentrations of dissolved ions, collectively creating a challenging habitat for microbial life. In this study, 89 bacterial isolates belonging to 20 genera were identified. Bacteria demonstrated significant osmotolerance, with some strains thriving at polyethylene glycol (PEG) concentrations exceeding 20%. Furthermore, these bacteria demonstrated halotolerance, high pH tolerance, and capacity to produce plant growth-promoting (PGP) traits under conditions of osmotic stress. Osmotolerant bacteria exhibited higher proficiency in siderophore production, potassium solubilization, and phosphorus solubilization, all of which are critical for supporting plant growth in nutrient-scarce and stressful environments, such as deserts. However, alginate production was higher in isolates that were less osmotolerant, indicating the potential for a compensatory mechanism in strains that were more sensitive. These findings highlight the complex strategies employed by desert bacteria to survive and support host plants in extreme environments. The present study not only enhances our understanding of microbial adaptations in arid ecosystems, but also provides important information for the development of potential applications for these bacteria in the reclamation of arid land and agricultural practices aimed at improving crop resilience to abiotic stress.

Keywords: drought; desertification; plant growth promoting rhizobacteria; plant growth promotion traits; abiotic stress tolerance (search for similar items in EconPapers)
JEL-codes: Q15 Q2 Q24 Q28 Q5 R14 R52 (search for similar items in EconPapers)
Date: 2024
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