حذف زيستي سفالكسين و آموكسي‌سيلين توسط كنسرسيومهاي ميكروبي و ارزيابي سيستم پيل سوختي ميكروبي در حذف آنتي¬بيوتيك¬ها

Biological removal of cephalexin an‎d amoxicillin by microbial consortia an‎d eva‎luation of microbial fuel cell system in removal of antibiotics

زيست شناسي سلولي مولكولي و ميكروبيولوژي

Beta-lactam antibiotics, particularly amoxicillin (AMX) an‎d cephalexin (CPX), are considered important emerging contaminants due to their widespread use an‎d incomplete removal in wastewater treatment plants, posing threats to human health an‎d ecosystems through biological toxicity an‎d the spread of antibiotic resistance. Therefore, this study was conducted in three parts with the aim of developing a sustainable biological approach for the removal of these antibiotics. In the first part, AMX- an‎d CPX-degrading strains an‎d consortia were isolated from activated sludge of municipal an‎d pharmaceutical wastewater, an‎d following molecular identification, synthetic consortia were designed, an‎d the performance of the systems was optimized an‎d compared using one-factor-at-a-time (OFAT) an‎d response surface methodology )RSM(; furthermore, biodegradation pathways an‎d metabolite toxicity were investigated using LC–MS an‎d MIC an‎d MTT assays. In the second part, the selec‎ted systems were immobilized on mineral pumice an‎d ceramic filters, an‎d their stability, degradation efficiency, an‎d reusability were eva‎luated. In the third part, the performance of the synthetic consortia was eva‎luated in a single-chamber, membrane-less microbial fuel cell (MFC) with a san‎d bed an‎d its corresponding photocatalytic system equipped with a ZnO/CuO photocathode (PMFC) under visible-light irradiation. In the first part, 94 antibiotic-degrading isolates, including 49 isolates for AMX an‎d 45 isolates for CPX, were isolated, an‎d 12 superior strains were used for the design of synthetic consortia. Following screening, the synthetic consortia AMXS an‎d CPXS, the natural consortia AMXN an‎d CPXN, an‎d the strains Chryseobacterium vaccae strain RM8 an‎d Bacillus wiedmannii strain RM5 were selec‎ted as the superior systems. Under optimal conditions, the removal efficiencies of AMX by AMXS, AMXN, an‎d RM8 were 94.8% in 36 h, 98.1% in 96 h, an‎d 95.24% in 72 h, respectively, while the removal efficiencies of CPX by CPXS, CPXN, an‎d RM5 were 98.55% in 48 h, 99.81% in 72 h, an‎d 94% in 60 h, respectively. Artificial consortia achieved antibiotic removal in a shorter time, whereas natural consortia showed a broader tolerance range up to a concentration of 400 mg/L. LC–MS analysis, through the identification of diverse metabolites in the selec‎ted systems, revealed the diversity of AMX an‎d CPX biodegradation pathways. The identification of simple terminal metabolites lacking aromatic an‎d beta-lactam structures indicated the progression of the process toward complete mineralization of the antibiotics. In the second part, immobilization of the selec‎ted systems increased the removal efficiency; the removal efficiency of AMXS increased from 90.39% to 99.6% within 30 h, RM8 from 80.6% to 97.2% within 36 h, CPXS from 98.2% to 99.3% within 30 h, an‎d RM5 from 95.4% to 98.8% within 36 h. Furthermore, the immobilized systems showed lower performance loss in synthetic media an‎d real wastewater an‎d maintained their reusability over 15 consecutive cycles. In the third part, AMXS in the MFC completely removed AMX at a concentration of 200 mg/L within 24 h an‎d achieved maximum voltage, power density, an‎d current density of 571 mV, 110.25 mW/m², an‎d 456 mA/m², respectively. The CPXS consortium also showed complete CPX removal at a concentration of 100 mg/L within 24 h, with maximum voltage, power density, an‎d current density of 634.67 mV, 106.15 mW/m², an‎d 429.33 mA/m², respectively. In the PMFC equipped with a ZnO/CuO photocathode, complete AMX removal at concentrations of 5, 70, an‎d 150 mg/L was achieved within 8, 12, an‎d 16 h, respectively, while complete CPX removal at concentrations of 70 an‎d 150 mg/L was achieved within 20 an‎d 24 h, respectively. The maximum voltages generated for AMX an‎d CPX were 847.5 an‎d 737.5 mV,

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