Chromate tolerant bacteria isolated from tannery effluent.

Area of Science:

• Environmental microbiology
• Microbial resistance studies

Background:

• Tanneries generate effluent containing heavy metals and antimicrobial compounds.
• Wastewater discharge can lead to the proliferation of resistant microorganisms in aquatic environments.

Purpose of the Study:

• To investigate the occurrence and characteristics of metal-tolerant and antibiotic-resistant organisms in tannery effluent.
• To determine the co-occurrence of metal and antibiotic resistance in bacterial isolates.

Main Methods:

• Isolation and characterization of heterotrophic bacteria and coliforms from tannery effluent.
• Determination of tolerance levels to various heavy metals (chromate, copper, cadmium, mercury) and antibiotics (cephaloridine, streptomycin, carbencillin, chloramphenicol, polymixin-B).

Main Results:

• Seventy-seven isolates (41 heterotrophs, 36 coliforms) tolerant to chromate (>50 microg/ml) were identified.
• Coliforms exhibited higher chromate resistance (200 microg/ml) than heterotrophs (>150 microg/ml).
• Co-resistance patterns were observed, with Hg2+-tolerant isolates also resistant to polymixin-B. Heterotrophs showed higher tolerance to copper and cadmium, while coliforms showed higher resistance to cephaloridine. Heterotrophs displayed greater resistance to streptomycin and carbencillin.

Conclusions:

• Tannery effluent is a reservoir for metal-tolerant and antibiotic-resistant bacteria, including coliforms and heterotrophs.
• Significant co-resistance between heavy metals and antibiotics exists, highlighting potential environmental risks.
• Understanding these resistance patterns is crucial for managing microbial pollution from industrial wastewater.