Proteomic and morphological insights into the exposure of Cupriavidus metallidurans CH34 planktonic cells and biofilms to aluminium.

Aluminium (Al) is one of the most popular materials for industrial and domestic use. Nevertheless, research has proven that this metal can be toxic to most organisms. This light metal has no known biological function and to date very few aluminium-specific biological pathways have been identified. In addition, information about the impact of this metal on microbial life is scarce. Here, we aimed to study the effect of aluminium on the metal-resistant soil bacterium Cupriavidus metallidurans CH34 in different growth modes, i.e. planktonic cells, adhered cells and mature biofilms. Our results indicated that despite a significant tolerance to aluminium (minimal inhibitory concentration of 6.25 mM Al2(SO4)3.18H2O), the exposure of C. metallidurans to a sub-inhibitory dose (0.78 mM) caused early oxidative stress and an increase in hydrolytic activity. Changes in the outer membrane surface of planktonic cells were observed, in addition to a rapid disruption of mature biofilms. On protein level, aluminium exposure increased the expression of proteins involved in metabolic activity such as pyruvate kinase, formate dehydrogenase and poly(3-hydroxybutyrate) polymerase, whereas proteins involved in chemotaxis, and the production and transport of iron scavenging siderophores were significantly downregulated.

New Medical Herbalism Formulations as a Targeted Therapeutic Strategies Used in Southern Tunisia to Promote Neo-Epithelium, Angiogenesis, and Collagen Biosynthesis and to Impede Scar Formation Post-Third-Degree Burned Skin.

The aim of the study is to assess the suitability of the herbal formulation for topical application as a skin burn dressing on the in vivo wound-closure of third-degree wound injuries. Rat wound models were used to prove the in vivo skin burn-healing process. Body weight gain, food and water intake, and behavior were investigated daily during treatment period. Cutaneous biopsies of the burned wound surfaces were monitored at days 4, 13, and 28. Formulation markedly (P < .05) increased wound repair rate and collagen production compared to untreated burnt skin. Macroscopic and histological analysis of the wound of formula (F)-treated group showed significant skin contraction rate and rapid wound healing without scar through regeneration of epidermis that were approved in formula mixed with honey (F-hY)- and Drs-treated wound compared with thymol, and the untreated wound tissues that were not covered by denuded epithelial. Furthermore, the wound healing efficacy of F-hY, F, and Drs cream was proved by decreased the amount of malondialdehyde compared to untreated rats. In conclusion, F and F-hY was found to promote cutaneous wound repair. In all case, the formula alone or mixed with honeybees was even better than thymol in the repair of cutaneous wound.

Impact of silver ions and silver nanoparticles on biochemical parameters and antioxidant enzyme modulations in Saccharomyces cerevisiae under co-exposure to static magnetic field: a comparative investigation.

The increase in simultaneous exposure to magnetic fields and other hazardous compounds released from industrial applications poses multiple stress conditions on the ecosystems and public human health. In this work, we investigated the effects of co-exposure to a static magnetic field (SMF) and silver ions (AgNO3) on biochemical parameters and antioxidant enzyme activities in the yeast Saccharomyces cerevisiae. Sub-chronic exposure to AgNO3 (0.5 mM) for 9 h resulted in a significant decrease in antioxidant enzyme activity, including glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), and glutathione transferase (GST). The total glutathione (GSH) level increased in yeast cells exposed to Ag. Additionally, a notable elevation in malondialdehyde (MDA) levels and protein carbonyl content was observed in both the AgNP and AgNO3 groups compared to the control group. Interestingly, the SMF alleviated the oxidative stress induced by silver nitrate, normalizing antioxidant enzyme activities by reducing cellular ROS formation, MDA levels, and protein carbonylation (PCO) concentrations.

Isolation and characterization of a newly chrysene-degrading Achromobacter aegrifaciens.

Polycyclic aromatic hydrocarbons (PAHs) are considered substances of potential human health hazards because of their resistance to biodegradation and carcinogenic index. Chrysene is a PAH with a high molecular weight (HMW) that poses challenges for its elimination from the environment. However, bacterial degradation is an effective, environmentally friendly, and cost-effective solution. In our study, we isolated a potential chrysene-degrading bacteria from crude oil-contaminated seawater (Bizerte, Tunisia). Based on 16SrRNA analysis, the isolate S5 was identified as Achromobacter aegrifaciens. Furthermore, the results revealed that A. aegrifaciens S5 produced a biofilm on polystyrene at 20 °C and 30 °C, as well as at the air-liquid (A-L) interface. Moreover, this isolate was able to swim and produce biosurfactants with an emulsification activity (E24%) over 53%. Chrysene biodegradation by isolate S5 was clearly assessed by an increase in the total viable count. Confirmation was obtained via gas chromatography-mass spectrometry (GC-MS) analyses. A. aegrifaciens S5 could use chrysene as its sole carbon and energy source, exhibiting an 86% degradation of chrysene on day 7. In addition, the bacterial counts reached their highest level, over 25 × 1020 CFU/mL, under the conditions of pH 7.0, a temperature of 30 °C, and a rotary speed of 120 rpm. Based on our findings, A. aegrifaciens S5 can be a potential candidate for bioremediation in HMW-PAH-contaminated environments.

Musico-bioremediation of seafood canning wastewater by Yarrowia lipolytica.

Due to the lack of water resources and the harmful effects of wastewater on environment and human health, treatment of wastewater becomes necessary. The present study explored the effect of musical sounds on the biological treatment of seafood canning wastewater by using Yarrowia lipolytica. Our results showed that low frequency (21 Hz to 1356 Hz) and high frequency (21 Hz to 16,214 Hz) musical sounds stimulated the growth of Y. lipolytica and increased the polluant removal efficiency. Such treatment decreased significantly the chemical oxygen demand (COD) and salinity as well as the color of this wastewater. Our study revealed that low frequency musical sounds are more effective in COD (87.5%) and salinity (44%) reduction as well as the decolorization (86.46%) of this effluent. Additionally, after 7 days of incubation significant yeast cell dry biomass (3.46 ± 0.22 g/L) and single cell proteins (46.45 ± 0.7 mg/g) were obtained under low frequency waves. Musico-bioremediation represents an innovative ecotechnological approach to wastewater treatment with low operating costs and significant environmental benefits.

Bioremediation potential of consortium Pseudomonas Stutzeri LBR and Cupriavidus Metallidurans LBJ in soil polluted by lead.

Pollution by lead (Pb) is an environmental and health threat due to the severity of its toxicity. Microbial bioremediation is an eco-friendly technique used to remediate contaminated soils. This present study was used to evaluate the effect of two bacterial strains isolated and identified from Bizerte lagoon: Cupriavidus metallidurans LBJ (C. metallidurans LBJ) and Pseudomonas stutzeri LBR (P. stutzeri LBR) on the rate of depollution of soil contaminated with Pb from Tunisia. To determine this effect, sterile and non-sterile soil was bioaugmented by P. stutzeri LBR and C. metallidurans LBJ strains individually and in a mixture for 25 days at 30°C. Results showed that the bioaugmentation of the non-sterile soil by the mixture of P. stutzeri LBR and C. metallidurans LBJ strains gave the best rate of reduction of Pb of 71.02%, compared to a rate of 58.07% and 46.47% respectively for bioaugmentation by the bacterial strains individually. In the case of the sterile soil, results showed that the reduction rate of lead was in the order of 66.96% in the case of the mixture of the two bacterial strains compared with 55.66% and 41.86% respectively for the addition of the two strains individually. These results are confirmed by analysis of the leachate from the sterile and non-sterile soil which showed an increase in the mobility and bioavailability of Pb in soil. These promising results offer another perspective for a soil bioremediation bioprocess applying bacterial bioremediation.

Morphological and Mechanical Characterization of Extracellular Vesicles and Parent Human Synoviocytes under Physiological and Inflammatory Conditions.

The morphology of fibroblast-like synoviocytes (FLS) issued from the synovial fluid (SF) of patients suffering from osteoarthritis (OA), rheumatoid arthritis (RA), or from healthy subjects (H), as well as the ultrastructure and mechanical properties of the FLS-secreted extracellular vesicles (EV), were analyzed by confocal microscopy, transmission electron microscopy, atomic force microscopy, and tribological tests. EV released under healthy conditions were constituted of several lipid bilayers surrounding a viscous inner core. This "gel-in" vesicular structure ensured high mechanical resistance of single vesicles and good tribological properties of the lubricant. RA, and to a lesser extent OA, synovial vesicles had altered morphology, corresponding to a "gel-out" situation with vesicles surrounded by a viscous gel, poor mechanical resistance, and poor lubricating qualities. When subjected to inflammatory conditions, healthy cells developed phenotypes similar to that of RA samples, which reinforces the importance of inflammatory processes in the loss of lubricating properties of SF.

Synovial Extracellular Vesicles: Structure and Role in Synovial Fluid Tribological Performances.

The quality of the lubricant between cartilaginous joint surfaces impacts the joint's mechanistic properties. In this study, we define the biochemical, ultrastructural, and tribological signatures of synovial fluids (SF) from patients with degenerative (osteoarthritis-OA) or inflammatory (rheumatoid arthritis-RA) joint pathologies in comparison with SF from healthy subjects. Phospholipid (PL) concentration in SF increased in pathological contexts, but the proportion PL relative to the overall lipids decreased. Subtle changes in PL chain composition were attributed to the inflammatory state. Transmission electron microscopy showed the occurrence of large multilamellar synovial extracellular vesicles (EV) filled with glycoprotein gel in healthy subjects. Synovial extracellular vesicle structure was altered in SF from OA and RA patients. RA samples systematically showed lower viscosity than healthy samples under a hydrodynamic lubricating regimen whereas OA samples showed higher viscosity. In turn, under a boundary regimen, cartilage surfaces in both pathological situations showed high wear and friction coefficients. Thus, we found a difference in the biochemical, tribological, and ultrastructural properties of synovial fluid in healthy people and patients with osteoarthritis and arthritis of the joints, and that large, multilamellar vesicles are essential for good boundary lubrication by ensuring a ball-bearing effect and limiting the destruction of lipid layers at the cartilage surface.

Growth and biofilm formation of Cupriavidus metallidurans CH34 on different metallic and polymeric materials used in spaceflight applications.

Bacteria biofilm formation and its complications are of special concern in isolated structures, such as offshore stations, manned submarines and space habitats, as maintenance and technical support are poorly accessible due to costs and/or logistical challenges. In addition, considering that future exploration missions are planned to adventure farther and longer in space, unlocking biofilm formation mechanisms and developing new antifouling solutions are key goals in order to ensure spacecraft's efficiency, crew's safety and mission success. In this work, we explored the interactions between Cupriavidus metallidurans, a prevalently identified contaminant onboard the International Space Station, and aerospace grade materials such as the titanium alloy TiAl6V4, the stainless steel AISI 316 (SS316) and Polytetrafluoroethylene (PTFE) or Teflon. Borosilicate glass was used as a control and all surfaces were investigated at two different pH values (5.0 and 7.0). Biofilms were almost absent on stainless steel and the titanium alloy contrary to Teflon and glass that were covered by an extensive biofilm formed via monolayers of scattered matrix-free cells and complex multilayered clusters or communities. Filamentous extracellular DNA structures were observed specifically in the complex multilayered clusters adherent to Teflon, indicating that the employed attachment machinery might depend on the physicochemical characteristics of the surface.

Therapeutic potential of second degree's skin burns by topical dressing of Teucrium ramosissimum that promotes re-epithelialization.

The aim of the report is to assess the protective effect of powder aerial part of Teucrium ramosissimum (TS) on the in vivo wound-healing of second-degree burn injuries. Teucrium phytocompounds were characterized by FTIR, HPLC, and GC/MS spectra. Burn wound models were employed to evaluate the in vivo wound-healing activity. Thirty six wistar rats with burn wounds were divided into six groups and treated daily with TS, the mixture of Teucrium and honey (TS-HY), thymol and Dermosalic® (0.05%) (DS) creams. Skin epithelialization was monitored on the 4th, 13th, and 21st days. Proteins and the level of malondialdehyde in the burned skin were assessed. Microscopic and macroscopic investigations of skin wound tissues showed significant wound closure rate via complete epidermal reepithelization and regeneration, higher protein content, collagen synthesis and deposition, hair follicles growth post wounding that were promoted in TS-, thymol-, TS-HY- and DS-treated wound tissues compared to the untreated burned wound tissues that was characterized by the absence of the epithelialization, vascularization and the formation of the epidermis layer. Additionally, the skin healing potential of TS and TS-HY was validated by markedly decreased of lipid peroxidation. Overall, TS was found to possess complete wound closure and improves the healing process.

Novel static magnetic field effects on green chemistry biosynthesis of silver nanoparticles in Saccharomyces cerevisiae.

The bacteriocidal properties of silver nanoparticles (AgNPs) depend on their average diameter (toxicity increases with decreasing diameter). In the present work, we describe novel green chemistry biosynthesis of AgNPs from AgNO3 added to cell-free culture medium of baker's yeast, Saccharomyces cerevisiae, yielding nanoparticles in the range 11-25 nm. However, when yeast was grown in a moderate static magnetic field, AgNPs obtained from the resulting cell-free culture medium, were significantly smaller (2-12 nm) than those obtained without magnetic field. These latter nanoparticles were highly crystalline, stable and near-uniform shape. Furthermore, the antibacterial activity of AgNPs obtained from static magnetic fields were greater than those from control cultures. Static magnetic fields show a promising ability to generate biocidal nanoparticles via this novel green chemistry approach.

Thymus hirtus sp. algeriensis Boiss. and Reut. volatile oil enhances TRAIL/Apo2L induced apoptosis and inhibits colon carcinogenesis through upregulation of death receptor pathway.

BACKGROUND: The aim of the study is to determine the anticancer activity of Thymus algeriensis (TS) and its underlying mechanisms using in vitro and in animal models. METHODS: HCT116 cells were treated with TS essential oil alone or with TRAIL, and then its anticancer effect was determined by using MTT assay, live dead assay, caspase activation and PARP cleavage. Further mechanisms of its anticancer effects was determined by analyzing expression of death receptor signaling pathway using Western blotting. A mouse model was also used to assess the antitumor potential of thyme essential oil. RESULTS: TS oily fraction showed tumor growth inhibitory effect even at lower concentration. TS induces apoptotic cell death as indicated by cleavage of PARP, and activation of the initiator and effector caspases (caspase-3, -8 and -9). Further, results showed that TS increases the expression of death receptors (DRs) and reduces the expression of TRAIL decoy receptors (DcRs). In addition, upregulation of signaling molecules of MAPK pathway (p38 kinase, ERK, JNK), down-regulation of c-FLIP, and overexpression of SP1 and CHOP were observed by TS. Further in animal model, intragastric administration of TS (12.5 mg/ml and 50 mg/ml) prevented colorectal carcinogenesis by blocking multi-steps in carcinoma. CONCLUSION: Overall, these results indicate that thymus essential oil promotes apoptosis in HCT116 cells and impedes tumorigenesis in animal model. Moreover, thyme potentiates TRAIL-induced cell death through upregulation of DRs, CHOP and SP1 as well as downregulation of antiapoptotic proteins in HCT116 cells. However, therapeutic potential of TS needs to be further explored.

Volatile oil of Teucrium alopecurus sensitizes colon cancer cells to TRAIL-induced cell death.

TNF-related apoptosis-inducing ligand (TRAIL/Apo2L), a member of cytokine family, is known to selectively induce apoptosis in cancer cells. However, developing resistance to TRAIL is a major obstacle in cancer therapy. In this study, the in vitro effect of Teucrium alopecurus (TA) essential oil on inhibition of cancer cell growth and enhancing TRAIL-induced apoptosis were investigated in colon cancer cells. Untreated tumor cell lines are used as controls. TA induced cell death and increased the anticancer effects of TRAIL as observed by cell toxicity, live/dead assay, cleavage of caspases and PARP. Furthermore, the mechanism of anticancer potentiating effect of TA was found to be linked with the upregulation of death receptors (DRs) and reduced expression of TRAIL decoy receptors (DcRs). TA also down-regulated antiapoptotic proteins and induced p53 in colon cancer cells. In addition, we observed upregulation of MAPK signalling pathway (p38 kinase, JNK, ERK) and increased expression of C/EBP homologous transcription factor (CHOP) and specificity protein 1 (SP1) by TA. These findings demonstrate the potent anticancer effect of bioactive constituents of Teucrium alopecurus essential oil.

Mycotoxin Removal by Lactobacillus spp. and Their Application in Animal Liquid Feed.

The removal of mycotoxins from contaminated feed using lactic acid bacteria (LAB) has been proposed as an inexpensive, safe, and promising mycotoxin decontamination strategy. In this study, viable and heat-inactivated L. acidophilus CIP 76.13T and L. delbrueckii subsp. bulgaricus CIP 101027T cells were investigated for their ability to remove aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEA), and deoxynivalenol (DON) from MRS medium and PBS buffer over a 24 h period at 37 °C. LAB decontamination activity was also assessed in a ZEA-contaminated liquid feed (LF). Residual mycotoxin concentrations were determined by UHPLC-FLD/DAD analysis. In PBS, viable L. acidophilus CIP 76.13T and L. delbrueckii subsp. bulgaricus CIP 101027T cells removed up to 57% and 30% of ZEA and DON, respectively, while AFB1 and OTA reductions were lower than 15%. In MRS, 28% and 33% of ZEA and AFB1 were removed, respectively; OTA and DON reductions were small (≤15%). Regardless of the medium, heat-inactivated cells produced significantly lower mycotoxin reductions than those obtained with viable cells. An adsorption mechanism was suggested to explain the reductions in AFB1 and OTA, while biodegradation could be responsible for the removal of ZEA and DON. Both viable LAB strains reduced ZEA by 23% in contaminated LF after 48 h of incubation. These findings suggest that LAB strains of L. acidophilus CIP 76.13T and L. delbrueckii subsp. bulgaricus CIP 101027T may be applied in the feed industry to reduce mycotoxin contamination.

relA and spoT Gene Expression is Modulated in Salmonella Grown Under Static Magnetic Field.

Virtually all bacterial species synthesize high levels of (p)ppGpp (guanosine penta- or tetraphosphate), a pleiotropic regulator of the stringent response and other stresses in bacteria. relA and spoT genes are, respectively, involved in synthesis and synthesis/biodegradation of (p)ppGpp. We aimed in this work to evaluate the impact of static magnetic field (SMF) 200 mT exposure on the expression of relA and spoT genes in Salmonella enterica Hadar. Bacteria were exposed to a SMF during 9 h, and RNA extraction was followed by reverse transcriptase polymerase chain reaction (RT-PCR). The relative quantification of mRNA expression levels using the 16S rRNA reference gene did not change during the SMF exposure. However, results showed a significant increase in gene expression for relA after 3 h of exposure (P < 0.05) and after 6 h for spoT (P < 0.05). The differential gene expression of relA and spoT could be considered as a potential stress response to a SMF exposure in Salmonella related to the production/degradation of (p)ppGpp.

High-performance biological treatment of tuna wash processing wastewater using Yarrowia lipolytica.

It is well known that the lack of an effective treatment of tuna wash processing wastewater may pose substantial environmental and public health hazards. The present work investigates the performance of biological treatment of tuna wash processing wastewater (TWPW) by using Yarrowia lipolytica. Under optimized experimental conditions (pH "6.40-6.50" and 29 °C), Y. lipolytica reduced the pollution level of the crude and the diluted TWPW after only 7 days of incubation. The Yarrowia treatment leaded to a reduction of 66% chemical oxygen demand, 69.8% total organic carbon, 66% salinity, and phosphorus total (100%) removal of the crude TWPW, while the treated-diluted TWPW revealed significant reductions in chemical oxygen demand and total organic carbon (75% and 74%, respectively), as well as salinity (68%). Interestingly, a total removal of nitrogen and phosphorus from the diluted TWPW was obtained. Under high salinity, an important Y. lipolytica biomass of 5 g L-1 is produced with high levels of lipids and protein contents at around 336 ± 12.2 mg g-1 and 302.15 ± 5.44 mg g-1, respectively. The phytotoxicity assessment of the treated TWPW on fenugreek seeds shows promising results, which reveals the good performance of Yarrowia treatment in reducing the toxicity of this wastewater.

Size Fractionation of Titania Nanoparticles in Wild Dittrichia viscosa Grown in a Native Environment.

We report a size fractionation of titania (TiO2) nanoparticles absorbed from the environment and found within wild Dittrichia viscosa plants. The nanoparticles were isolated by extraction and isolation from distinct plant organs, as well as from the corresponding rhizosphere of wild, adult plants. The collected nanoparticles were characterized by scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (STEM-EDS). More than 1200 TiO2 nanoparticles were analyzed by these techniques. The results indicated the presence of TiO2 nanoparticles with a wide range of sizes within the inspected plant organs and rhizospheres. Interestingly, a size selective process occurs during the internalization and translocation of these nanoparticles (e.g., foliar and root uptake), which favors the accumulation of mainly TiO2 nanoparticles with diameters <50 nm in the leaves, stems, and roots. In fact, our findings indicate that among the total number of TiO2 nanoparticles analyzed, the fraction of the particles with dimensions <50 nm were 52% of those within the rhizospheres, 88.5% of those within the roots, 90% of those within the stems, and 53% of those within the leaves. This significant difference observed in the size distribution of the TiO2 nanoparticles among the rhizosphere and the plant organs could have impacts on the food chain and further biologicals effects that are dependent on the size of the TiO2.

Dietary exposure of Tunisian adult population aged from 19 to 65 years old to pesticides residues.

Dietary exposure of the Tunisian adult population to pesticide residue was assessed using the Total Diet Study method. In the present study 170 pesticides were searched for in 42 aggregated foods characterised by 64 food samples representing the Tunisian diet. All the food samples were collected, prepared, and analysed for remains of pesticides including organochlorine, organophosphorous, carbamates and pyrethroids. The GC-MS analysis and the LC-MS/MS analysis and some other specific analytical methods were employed for the quantification of the pesticide residues in the food samples. Results revealed that21pesticides reached amounts greater than the LOQ(12.3%) and 149 pesticides reached amounts below the LOD (88%).For the 21 pesticides quantified, the ADI was not exceeded. For the 149 non-quantified pesticides, an interval defined by the lower and upper bounds was defined to assess the dietary exposure of the Tunisian adult population to those pesticides. We conclude that 8 pesticides theoretically exceed the ADI with the 95th percentile of exposure, those are: Diféthialone, Brodifacoum, Bromadiolone, Glufosinate, Heptachlor, Dieldrin Aldrin Oxydemeton-methyl. This study concludes that there is a low dietary exposure to pesticide residue of the Tunisian adult population. In fact, all the cases where the ADI was exceeded were theoretical due to the lower ADI value used.

Alleviated Actions of Plantago albicans Extract on Lead Acetate-Produced Hepatic Damage in Rats Through Antioxidant and Free Radical Scavenging Capacities.

The aim of this study was to explore the possible protective mechanisms and to determine the antioxidant capacity of phenolic compounds extracted from Plantago albicans against lead acetate-induced hepatic injury. High performance liquid chromatography-photo diode array/electrospray ionization-mass spectrometry (HPLC-PDA/ESI-MS) assay was used to identify the P. albicans extract phenolic compounds. Animals received 100 mg of lead acetate/kg of body weight (bw) in the drinking water for a period of 30 days. The other groups of rats were orally administered with silymarin (300 mg/kg bw) or the P. albicans extract at two doses (100 and 300 mg/kg of bw), once daily, by gastric gavage for the same time. The P. albicans exhibited high total phenolic, flavonoid, and anthocyanin contents. The antioxidant in vitro activity demonstrated that the P. albicans exhibits an important effect against deleterious reactive species. The in vivo results showed that P. albicans prevented the lead acetate-induced significant changes on serum and liver lipid levels. In contrast, P. albicans succeeded in improving the biochemical parameters of serum and liver bringing them closer to the normal values of the control group. It also significantly promoted (P < .05) pro-inflammatory cytokines (TNF-α, IL-6, and NF-κB) in the liver of the experimental animals. The evaluated sample with HPLC-PDA/ESI-MS method showed to contain 10 dominant polyphenols, 2 hydroxycinnamic acids (p-coumaric acid and chlorogenic acids), 4 flavones (Apigenin, Luteolin, Cirsiliol, and Luteolin-7-O-rutinoside), and an anthocyanin (cyanidin-3-glucoside). Hence, it can be concluded that P. albicans could be a potent source of health-beneficial phytochemicals providing a novel therapy to protect liver against lead exposure.

Dual Valorization of Olive Mill Wastewater by Bio-Nanosynthesis of Magnesium Oxide and Yarrowia lipolytica Biomass Production.

This research investigates an efficient dual valorization of olive mill wastewater in the biosynthesis of magnesium oxide nanoparticles and in the depollution of the effluent by Yarrowia lipolytica growth evaluation. After removal of polyphenols, the recovered biophenols were reacted with the magnesium precursor to provide magnesium oxide nanoparticles. In order to confirm the biosynthesized magnesium oxide nanoparticles, several analyses were undertaken. The Fourier transform infrared spectrum gives a broad absorption at 658 cm-1 confirming the presence of the magnesium oxide nanoparticles, while the UV/VIS absorption spectroscopy reveals an intense transition with a maximum absorption at 300 nm. The X-ray diffraction and transmission electron microscopy analyses show that nanoparticles are in pure cubic crystalline with spherical and hexagonal shapes (average size is 19.4 nm). The zeta potential analysis illustrates a negative potential proving a good stability of the biosynthesized nanoparticles. Nanoparticles were assigned for their in vitro antibacterial activity against Escherichia coli, Enterobacter aerogenes, Salmonella typhimurium, Staphylococcus cohnii, and Bacillus niacini. The evaluation of the growth of Yarrowia lipolytica on the recovered olive mill wastewater after removal of polyphenols yielded 3.2 g/L of the Yarrowia biomass in 72 h without nutriment additions, providing an important decrease of chemical oxygen demand (73 %).