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Browsing by Author "Ismail, Fatma M.A. Elsayed"

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  • Biodegradation of paracetamol and its intermediate metabolite hydroquinone by bacterial strains isolated from two mines of the iberian pyrite belt
    Publication . Ismail, Fatma M.A. Elsayed; Costa, Maria Clara; Carlier, Jorge Dias
    The main objective of the current study was to isolate bacterial strains able to biodegrade the emerging pollutants paracetamol (APAP) and hydroquinone (HQ), amongst the most worldwide prescribed drugs, also frequently detected in wastewater treatment plants influents and effluents and the environment. The most promising microbial consortia of Poderosa and Lousal mines for APAP removal were selected based on the previous reports of PROBIOMA project (European Regional Development Fund ERDF - Interreg V-A Spain-Portugal program (POCTEP)). The ability of the selected microbial consortia to remove APAP from the Mineral Salt Medium (MSM) at an initial concentration of about 500 mgL-1 (MSM-APAP (500 mgL-1)), under dark shaking conditions of 160 rpm at 25 °C, was confirmed using UV-vis molecular spectroscopy. Subsequently, the isolation step from selected samples proceeded from three successive enrichment cultures using MSM-drug (500 mgL-1) under the aforementioned conditions by spreading first on LB-drug and then on MSM-drug (500 mgL-1) agar plates and resulted in seven isolates able to utilize APAP as sole carbon source, and identified according to 16S rRNA gene sequence analysis as members of genera Aeromonas, Bacillus (two isolates), Niallia, Paraburkholderia, Rhizobium, and Variovorax, as well as one HQ utilizing isolate (Mycolicibacterium sp.). The HPLC analysis of APAP removal, in MSM-APAP (500 mgL-1) under the same culture conditions, by the two putative APAP biodegrading Bacillus sp. isolates revealed that Bacillus sp. (PDE3.1) showed maximal APAP %removal of 63+3 after 18 days, while Bacillus. sp. (PLC2.1) showed %removal of only 8+1 at the end of the experiment after 21 days. The key metabolites of APAP degradation (4-aminophenol and HQ) were detected through GC-MS analysis in the experiment with Bacillus sp. (PDE3.1) at very low concentrations. Then, the seven potential APAP biodegrading bacterial isolates were tested for APAP removal in MSM at a lower concentration of 50 mgL-1. Rhizobium sp. (PDE3.3) and Paraburkholderia sp. (PLA3.3) seemed the most promising where APAP %removal was 49±4 and 47.9±0.9, respectively. Later, the co-culture of the three most promising isolates (Rhizobium sp. (PDE3.3), Paraburkholderia sp. (PLA3.3), and Bacillus sp. (PDE3.1) didn’t improve the %removal compared with the pure cultures, while the co-culture with the seven potential APAP biodegrading isolates did not show removal capacity. Mycolicibacterium sp. (HPB1.1) showed at least 88% removal of HQ from MSM-HQ (50 mgL-1) after four days; hence, was checked for APAP removal in MSM-APAP (50 mgL-1) and showed APAP %removal of 41.6±0.1. Overall, some bacterial strains isolated from Poderosa and Lousal mines showed removal capacity; hence, more efforts should be directed at investigating if biodegradation is the main removal mechanism involved, and at exploring the biodegradation potentials of The Iberian Pyrite Belt mines associated bacteria.
    2022-12-12Master thesis Open Access Show more