Bioremediation potential of cadmium-resistant bacteria isolated from water samples of rivulet Holy Kali Bein, Punjab, India

Abstract

The present study was conducted with the goal of isolation, characterization, optimization and exploitation of the cadmium (Cd) bioremediation potential of Cd-resistant bacterial strains from the Holy Kali Bein, Punjab, India. From biochemical analysis, protein-based identification by using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectroscopy (MALDI-TOF) and 16S rRNA sequencing the isolate KCd7 identified as Aeromonas caviae, KCd8 as Exiguobacterium indicum and isolate KCd9 as Acinetobacter haemolyticus. The isolates KCd7, KCd8 and KCd9 exhibited high degree of Cd resistance, up to 400, 400 and 500 mg/L respectively, with multiple antibiotic resistances (MAR) index above 0.0, 0.08 and 0.016 respectively. The optimal conditions were recorded as: initial metal concentration 150 mg/L, temperature 37 °C for all three isolates, pH 8 for KCd7 and pH7.5 for KCd8 and KCd9. Results showed that the isolates KCd7, KCd8 and KCd9 can remove 100% within 168 h and 70% within 168 h and 100% within 144 h of Cd respectively. The study’s results demonstrated that the bacterial isolate KCd9 (Acinetobacter haemolyticus) is more effective than other bacterial isolates since it can completely eliminate cadmium from the aqueous medium in just 144 h and it came to the conclusion that these bacteria have the potential for bioremediation of cadmium.