Mitigating antibiotic pollution using cyanobacteria: Removal efficiency, pathways and metabolism.

Area of Science:

• Environmental Science
• Biotechnology
• Ecotoxicology

Background:

• Pharmaceuticals and personal care products (PPCPs) in wastewater pose environmental threats, requiring novel treatment methods beyond conventional plants.
• Harmful algal blooms (HABs) are an ecological problem with potential for valorization, rarely explored for contaminant removal.
• High concentrations of antibiotics like tetracycline present significant challenges for wastewater treatment.

Purpose of the Study:

• To investigate the efficacy, mechanisms, and toxin release effects of using the HAB species Microcystis aeruginosa for removing high concentrations of tetracycline.
• To compare the performance of M. aeruginosa with the chlorophyte alga Chlorella pyrenoidosa in tetracycline removal.
• To explore the potential for reusing HABs for environmental remediation and antibiotic removal.

Main Methods:

• Cultivation of Microcystis aeruginosa and Chlorella pyrenoidosa for tetracycline removal experiments at concentrations of 10-100 mg L⁻¹.
• Kinetic analysis to determine probable removal pathways, including bioremediation and abiotic processes.
• Analysis of degradation by-products, pH changes, and microcystin-LR toxin levels in M. aeruginosa treatments.

Main Results:

• M. aeruginosa achieved over 98.0% tetracycline removal within 2 days, significantly higher than C. pyrenoidosa (36.7%-93.9%).
• Bioremediation was the dominant removal pathway for M. aeruginosa (71.6%) compared to C. pyrenoidosa (20.5%).
• M. aeruginosa demonstrated high tolerance to tetracycline, with significantly lower microcystin-LR release compared to controls.

Conclusions:

• Harmful algal bloom species, specifically M. aeruginosa, are effective and rapid removers of high-concentration tetracycline.
• The study supports the reuse of HABs for high-concentration antibiotic remediation, with potential control over toxin release.
• Mechanisms involve enhanced hydrolysis and inhibition of photolytic reactions, with bioremediation playing a key role.