Exploration of potent phosphate solubilizing bacteria with evaluating pesticide, heavy metal and antibiotic - resistant properties for application as biofertilizer

Abstract

Abstract The present study aimed to explore the potent phosphate solubilizing bacteria (PSB) from the rhizosphere by isolation, screening and characterization to apply as P biofertilizer for improving the plants growth. Due to exhibiting the higher inorganic P solubilization (163.75–245.49 mg/l) property, four isolates (KUJ1PSB1, KUJ1PSB2, KUJ1PSB10 and KUJ1PSB12) were chosen as the potent PSB from a total of fourteen hollow zone exhibiting colonies grown on Pikovskaya’s agar media. Of four isolates, KUJ1PSB2 showed the highest inorganic P solubilization (245.49 ± 0.59 mg/l, 24.97–37.30%) and excellent plant (Solanum lycopersicum) growth promotion (shoot length − 30.43% and leaf number − 50%) efficiencies along with other favourable biochemical properties; indole acetic acid (IAA) production (96.06 µg/ml), pesticide-resistant (50–2000 mg/l), antibiotic-resistant (< 10 - >1000 mg/l), heavy metal -resistant (> 2000 mg/l) and -removal (Cd 93.1%, Zn 53.6%, Pb 72%, and Cu 49%). High P solubilization and IAA production efficiencies of KUJ1PSB2 are important factors for excellent plant growth. Therefore, KUJ1PSB2 was selected as the best PSB among four potential isolates and identified by the 16S rDNA sequencing. The 16S rDNA (1000 bp) sequence of KUJ1PSB2 showed 98.81% similarity with Serratia marcescens and a phylogenetic analysis revealed its position among the related species, which collectively identified it as Serratia marcescens KUJ1PSB2 strain. Finally, it can be concluded that Serratia marcescens KUJ1PSB2 would be a potential P solubilizing biofertilizer for applying in practical fields to produce sustainably higher rate of crop at low-cost through the organic agriculture practices and food production for the benefit of the farmers.