Genomic analysis of phosphate-solubilizing bacteria Enterobacter ludwigii I42 and its impact on maize growth

Abstract

Phosphorus (P) is an essential macronutrient required for optimal plant growth, yet its limited bioavailability in soil often restricts crop growth and yield. Phosphate-solubilizing bacteria (PSB) have the capacity to convert insoluble inorganic and organic P into forms readily absorbed by plants. In the present study, Enterobacter ludwigii I42 was investigated to elucidate the molecular mechanisms responsible for its P-solubilizing and growth-promoting properties in maize crops. E. ludwigii I42 was isolated and assessed for its ability to promote plant growth through pot experiments and genomic analyses. The I42 strain exhibited strong capabilities in solubilizing P and potassium (K), as well as producing indole acetic acid (IAA) and siderophores. In pot trials, the application of strain I42 significantly enhanced maize seedling growth, including increase in maximum leaf area, fresh weight, dry weight, stem diameter, and the availability of P and K in the rhizosphere soil. Analysis of the rhizosphere microbiome revealed that I42 modified the bacterial community by enriching beneficial genera, such as Bacillus and Arthrobacter . Whole-genome sequencing of I42 revealed a 4,719,369-bp circular chromosome with an average GC content of 54.5%. Genomic data confirmed the presence of genes associated with P solubilization, IAA biosynthesis, and siderophore production. Comparative genomic analysis identified 133 unique genes in strain I42 that may contribute to plant growth-promoting properties. E. ludwigii I42 demonstrates strong potential as a plant growth-promoting bacterium by enhancing maize growth through P solubilization, phytohormone production, and rhizosphere bacterial community modification. Genomic analyses suggest that strain I42 possesses several genes related to phosphate solubilization, IAA biosynthesis, and siderophore production. These findings highlight E. ludwigii I42 as a promising biofertilizer candidate for sustainable agricultural practices aimed at improving crop productivity.