Publications internationales
Résumé: Environmental pollution resulting from the accumulation of plastic waste poses a ma- jor ecological challenge. Biodegradation of these polymers relies on microorganisms capable of decomposing them, generally through the biodeterioration, biofragmentation, assimilation, and mineralization stages. This study evaluates the contribution and efficacy of indigenous soil yeasts isolated from a northeastern Algerian landfill in degrading low-density polyethylene (LDPE) plastic bag films. Candida tropicalis SLNEA04 and Rhodotorula mucilaginosa SLNEA05 were identified through internal transcribed spacer (ITS) and large subunit ribosomal RNA gene sequencing. These isolates were then tested for their ability to biodegrade LDPE films and utilized as the sole carbon source in vitro in a mineral salt medium (MSM). The biodegradation effect was examined using scanning electron microscopy (SEM), attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spec- troscopy, and X-ray diffraction (XRD). After 30 days of incubation at 25 ◦C, a significant weight loss was observed compared to the control for both cultures: 7.60% and 5.53% for C. tropicalis and R. mucilaginosa, respectively. SEM analysis revealed morphological alterations, including cracks and holes, ATR-FTIR detected new functional groups (alcohols, alkynes, aldehydes, alkenes and ketones), while XRD identified changes in the polymer crystallinity and phase composition. These findings underscore the potential of the two yeast isolates in LDPE biodegradation, offering promising insights for future environmental applications.
Résumé: Biodegradation poses a challenge for environmentalists and scientific community, offering a potential solution to the plastic waste problem. This study aims to investigate the biological degradation of low-density polyethylene (LDPE) bags by a fungus in both batch and continuous cultures, with the goal of identifying an eco-friendly and cost-effective waste management strategy. The fungal strain Rhizopus arrhizus SLNEA1, isolated from a landfill located in northeastern Algeria, was tested for its capability to degrade LDPE films and utilize them as a sole carbon source in batch (α-LDPE) and continuous (γ-LDPE) cultures. The results indicated a higher rate of weight loss for γ-LDPE (29.74%) compared to α-LDPE (23.77%). The biodegradation effect was examined using scanning electron microscopy (SEM), Energy Disper- sive X-ray Spectroscopy (EDS) and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) to evaluate morphological and chemical changes in LDPE samples, highlighting alterations of LDPE films through cracks, veins and holes under SEM and chemical transformation and appearance of new functional groups in the FTIR data. Rhizopus arrhizus SLNEA1 demonstrated the ability to break down and utilize LDPE films as a carbon source. This isolate shows promise for LDPE biodegradation applications, which may be leveraged for the development of future plastic degradation systems involving fungi.
Résumé: The emergence of antibiotic-resistant pathogens has led to a growing demand for novel and effective antimicrobial agents. In our study, a novel 3-(2-chloroacetyl) oxazolidine-2-one was synthesized and screened for its antimicrobial activity against thirteen pathogenic bacteria and five fungal species. The results showed that the new compound, L1, exhibited potent antibacterial activity, with inhibition zones ranging from 14 to 25 mm and minimum inhibitory concentrations (MICs) of 125 to 500 μg/mL. Regarding antifungal activity, all strains were susceptible to the tested molecule, with inhibition zone diameters ranging from 16 to 36.5 mm and MICs ranging from 7.81 μg/mL to 250 μg/mL, Tests against virulence factors demonstrated that the new molecule significantly inhibited biofilm formation, motility and quorum sensing. In terms of antioxidant capacity, the molecule tested showed a (2, 2-diphenyl-1- picrylhydrazyl) (DPPH) scavenging activity with an IC50 value of 5.58 ± 0.02 μg/mL, and an anti-inflammatory effect demonstrated a percentage inhibition of about 84.38 ± 5.11%. For the HOMO-LUMO analysis, the compound has a positive log p-value, confirming its lipophilicity and biological activity. A molecular anchoring study was performed to understand their binding modes in the active site of the Staphylococcus aureus Thymidylate Kinase (TMK) binding site. In conclusion, these results are promising for the novel 3-(2-chloroacetyl) oxazolidine-2 in medical and pharmaceutical applications.
Résumé: The emergence of antibiotic-resistant pathogens has led to a growing demand for novel and effective antimicrobial agents. In our study, a novel 3-(2-chloroacetyl) oxazolidine-2-one was synthesized and screened for its antimicrobial activity against thirteen pathogenic bacteria and five fungal species. The results showed that the new compound, L1, exhibited potent antibacterial activity, with inhibition zones ranging from 14 to 25 mm and minimum inhibitory concentrations (MICs) of 125 to 500 μg/mL. Regarding antifungal activity, all strains were susceptible to the tested molecule, with inhibition zone diameters ranging from 16 to 36.5 mm and MICs ranging from 7.81 μg/mL to 250 μg/mL, Tests against virulence factors demonstrated that the new molecule significantly inhibited biofilm formation, motility and quorum sensing. In terms of antioxidant capacity, the molecule tested showed a (2, 2-diphenyl-1- picrylhydrazyl) (DPPH) scavenging activity with an IC50 value of 5.58 ± 0.02 μg/mL, and an anti-inflammatory effect demonstrated a percentage inhibition of about 84.38 ± 5.11%. For the HOMO-LUMO analysis, the compound has a positive log p-value, confirming its lipophilicity and biological activity. A molecular anchoring study was performed to understand their binding modes in the active site of the Staphylococcus aureus Thymidylate Kinase (TMK) binding site. In conclusion, these results are promising for the novel 3-(2-chloroacetyl) oxazolidine-2 in medical and pharmaceutical applications.