Insights into using Kosakonia oryzae AG15 in liquid formulations containing sodium alginate, glycerol, and gum arabic for the sustainable development of Phaseolus vulgaris L.

Abstract

This study investigated a liquid formulation containing the plant growth-promoting rhizobacterium (PGPR) Kosakonia oryzae AG15 associated with Agave spp., collected in the State of Paraíba, Brazil, and containing sodium alginate, glycerol, and gum arabic as stabilizers. The morphological, biochemical, and functional characterization of the strain confirmed its potential for indole-3-acetic acid production and nitrogen fixation, with growth conditions at 30 °C, pH 7.5, and 24 h of incubation in Luria-Bertani medium supplemented with sucrose, reaching a biomass of 3.25 g L⁻¹. The optimized bioinoculant formulation, composed of 0% sodium alginate, 0.5% glycerol, and 0.5% gum arabic, maintained a viable cell population of 10⁵ CFU/mL during 180 days of storage at 7 °C. As an agronomic application in Phaseolus vulgaris L., the liquid inoculant demonstrated its effectiveness, with increases in root iron content (26.47%), root dry weight (15.15%), shoot dry weight (8.82%), root length (7.4%), and shoot length (26.21%). Taken together, these results suggest that the optimized liquid formulation of K. oryzae AG15, stabilized with gum arabic and glycerol, is a promising bioinoculant for improving the development of P. vulgaris L., and applications in other plants can be explored to support sustainable agricultural practices.