Screening and
molecular identification of Mercury Tolerant Bacteria from Dairy Waste and Evaluation
of their Bioremediation Potential by Atomic Absorption Spectroscopy
Kulkarni Sarika Satish, Narsinge Anil Panditrao, Chavan Ranjana Shirish and Mali
Gajanan Vishnu
Res. J. Chem. Environ.; Vol. 29(10); 83-89;
doi: https://doi.org/10.25303/2910rjce083089; (2025)
Abstract
The present study aimed to isolate, to screen and to identify molecularly mercury-resistant
bacteria from industrial effluents and to evaluate their mercury-reducing potential
using Atomic Absorption Spectroscopy (AAS). Effluent samples from the dairy industries
in Pune city were collected and enriched in nutrient broth supplemented with HgCl₂
for the isolation of mercury-resistant bacterial isolates. The isolates were obtained
on different agar media (Nutrient Agar, LB Agar, Minimal Agar and Mueller–Hinton
Agar) containing mercury concentrations ranging from 10 ppm to 200 ppm. The morphological
and biochemical characterizations were performed for selected isolates. The mercury
reduction by selected isolates was evaluated by using AAS over 48 hours.
Molecular identification of potent isolates was performed by 16S rRNA gene sequencing,
followed by phylogenetic analysis using MEGA 11 software. Out of 25 isolates, three
isolates H1, H6, H7 exhibited growth at 200 ppm HgCl₂, while K1 exhibited growth
at 100 ppm concentration of HgCl₂. Based on AAS analysis, H1 and H6 demonstrated
the highest mercury reduction, 7.44 ppm and 16.76 ppm respectively after 30 hours
of incubation. Morphological, biochemical and molecular characterization revealed
H1 as Pseudomonas aeruginosa and H6 as Bacillus paranthracis. The study demonstrated
that Pseudomonas aeruginosa and Bacillus paranthracis isolates possess strong mercury
reduction capabilities, highlighting their potential applications in the bioremediation
of mercury-contaminated environments.
