Exploiting beneficial bacteria as plant probiotics for sustainable crop enhancement

Plant probiotics, defined as beneficial bacteria that colonize the rhizosphere, represent a promising eco-friendly alternative to synthetic agrochemicals. These microorganisms can enhance plant growth through mechanisms such as nutrient solubilization, and stress mitigation. Although numerous studies have highlighted their potential in various crops, systematic evaluation of strain-specific effects under standardized conditions remains limited. This work assesses the potential of selected bacterial isolates to promote growth, nutrient acquisition, and abiotic stress tolerance in tomato seedlings. A collection of 30 soil bacteria were isolated from healthy tomato plants in organic farms. Isolates were screened in vitro for plant growth–promoting traits including potassium, phosphate and zinc solubilization. Two promising strains of Bacillus sp. (strain Bv and Ba) were selected for greenhouse trials. Surface-sterilized tomato seeds were inoculated with bacterial suspensions (108 CFU mL ¹) and grown under controlled conditions for six weeks. Plant growth parameters, chlorophyll content, and drought tolerance were assessed. Root colonization was also quantified. Two bacterial treatments significantly increased shoot height (15–25%), root length (20– 30%), and total biomass (18–28%). Chlorophyll content rose by 12–18%, compared to controls. Under drought stress, inoculated plants exhibited higher relative water content (10–15% increase) and maintained 25% greater biomass than controls. Quantification analysis confirmed effective root colonization with densities of 106–107 CFU g ¹ root. These results demonstrate that plant probiotic bacteria can substantially enhance growth and drought resilience, offering a sustainable alternative to chemical inputs in agriculture. Integrating these strains into crop management strategies could improve yield stability and environmental sustainability.