Isolation, Characterization and Optimization of Lead Resistant Bacteria and Possible Application in Bioremediation

The present study describes three lead-resistant bacterial isolates (KPb1, KPb5, and KPb7) that were isolated from water samples of the River Holy Kali Bein, Punjab, India. The isolates were found to resist and bioaccumulate lead, and maximum tolerated concentrations were found to be 750 mg/L by KPb1 and KPb5, and 800 mg/L by isolate KPb7, respectively. Additionally, isolates KPb1, KPb5, and KPb7 had Multiple Antibiotic Resistance (MAR) index values of 0.08, 0, and 0.25, respectively. The isolate KPb1 was identified as Klebsiella pneumonia, KPb5 as Serratia marcescens, and KPb7 as Microbacterium resistens based on biochemical analysis protein-based identification utilizing Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectroscopy and 16S rRNA sequencing. According to the findings, these strains were cultivated optimally at 37 °C and pH 7.0 for KPb5 and KPb7 and pH 7.5 for KPb1. Under optimum conditions, the bacterial isolates KPb7 showed the greatest potential for bioremediation, and reduced 100% of the lead in 96 h, KPb1 reduced 100% of the lead in 144 h, and KPb5 reduced 90% of the lead in 168 h. Our research established a baseline for the bioremediation of lead in an aqueous medium and concluded that these bacteria (KPb1, KPb5, and KPb7) are viable options for the bioremediation of lead.