Isolation and Molecular Identification of Novel PhosphateSolubilizing Bacteria and Their Plant Growth-Promoting Activities.

This investigation aimed to isolate and characterize novel phosphate-solubilizing
bacterial (PSB) isolates using both conventional and molecular techniques. Additionally, the
study evaluated their plant growth promoting activity on sugar beet (Beta vulgaris). Three
distinct colonies that produced clear halos on Pikovskaya's agar (PKA) plates were selected and
designated as YMP5, YMP6, and YMP7 for microbiological and molecular characterization. Due
to the 16S rRNA gene sequence analysis and comparison with strains in the NCBI GenBank
database, isolates YMP5 and YMP7 were identified as Pseudomonas indica, while isolate YMP6
belonged to the genus Priestia. Phylogenetic analysis further confirmed that YMP5 and YMP7
clustered with Pseudomonas indica strains IMT37 and NBRC 103045, whereas YMP6 clustered
with Priestia endophytica strain 2DT. The 16S rDNA gene sequences of these PSB isolates were
submitted to the NCBI database under accession numbers PV652948 to PV652950. In terms of
plant growth promoting activities, all isolates positively influenced vegetative growth
parameters, enhanced NPK nutrient content, and increased photosynthetic pigment
concentrations compared to the untreated control. These findings suggest that beneficial PSB
strains can be isolated from Egyptian soils and utilized as sustainable bio-inoculants in
agriculture. Such bio-fertilizers have the potential to enhance plant development, reduce reliance
on chemical fertilizers, and mitigate crop yield losses.