Vibrio Fischeri Research Articles

Photolytic Degradation of the Insecticide Clothianidin in Hydrochar Aquatic Suspensions and Extracts

In this study, the aqueous photolytic degradation of the neonicotinoid pesticide clothianidin was studied in suspensions and aqueous extracts of hydrochar produced from olive kernels. A slight and nonsignificant decrease in the photodegradation rate of clothianidin in aqueous extracts of hydrochar (HCw) with an initial concentration of hydrochar ranged from 50 to 400 mg L−1 (rate constants ranged between k = 0.0034 and 0.0039 min−1) was observed in comparison to the respective rate in the bi-distilled water (k = 0.0040 min−1). On the contrary, in the presence of hydrochar suspensions (HCp), a significant decrease was observed for 50 mg L−1 hydrochar particle concentration (k = 0.020 min−1), while for higher concentrations (100 to 400 mg L−1), rate constants increased but with nonsignificant differences compared with the kinetics followed in the absence of them. Generally, the photodegradation rate of clothianidin, in the presence of HCw and HCp, is reduced compared to the photodegradation rate in bi-distilled aqueous solutions, except in the case of the aqueous suspension with an HCp concentration of 200 mg L−1. The transformation products (TPs) of clothianidin formed in the photolytic degradation processes were identified using ultrahigh-performance liquid chromatography coupled with accurate high-resolution mass spectrometry technique (UHPLC-LTQ-ORBITRAP). The formation profiles of TPs varied according to the matrix showing different degrees of participation of direct and indirect (photosensitized) phototransformation pathways. Photolytic degradation of clothianidin takes place mainly through denitration, hydroxylation and dechlorination pathways. Finally, the toxicity of the identified TPs was studied using the Vibrio fischeri bioassay. Toxicity was slightly reduced after 300 min of irradiation while maximum value was observed after 180–240 min of irradiation showing the formation of more toxic TPs along the photochemical degradation.

Ecotoxicity and rapid degradation of quaternary ammonium compounds (QACs) subjected to combined vacuum UV and UV-C treatment

Quaternary ammonium compounds (QACs) are active ingredients in a palette of commercially available disinfectants, sanitizers, and biocides. QACs are widely used because of their broad-spectrum antimicrobial properties but the ubiquitous uses have resulted in frequent detection in aquatic and terrestrial matrices including domestic wastewater, surface waters, urban soils and sediments. An increased domestic QACs consumption has increased the environmental occurrence, and investigation of mitigation methods and effects on non-target organisms are in demand. In this study, we examined the potential ecotoxicity of six QACs and investigated the effect of combined vacuum UV (185 nm) and UV-C (254 nm) irradiation (VUV/UVC) on degradation and mitigation of ecotoxicity of QACs. The study showed that combined VUV/UVC irradiation facilitated rapid degradation of benzalkonium chloride, benzethonium chloride, didecyldimethylammonium chloride, dodecyltrimethylammonium chloride, and hexadecyltrimethylammonium chloride. The estimated half-lives varied between 2 and 7 min, and degradation was affected by the initial QAC concentrations, the UV fluence, and the water matrix. The potential ecotoxicity of QACs and VUV/UVC treated QACs was examined using a battery of test organisms that included the luminescent bacterium Aliivibrio fischeri, the gram-negative and gram-positive bacteria Escherichiacoli and Enterococcus faecalis, the freshwater microalga Raphidocelis subcapitata, and the crustacean Daphia magna. The potential for trophic transfer of QACs was investigated in a simplified aquatic food web. Test organisms from different trophic levels were included to assess adverse effects of bioactive compounds in VUV/UVC treated samples including transformation products. The study showed that several QACs were highly toxic to aquatic test organisms with EC50 and/or EC20 values < 1 μM. VUV/UVC treatment of QACs resulted in substantial photolysis of the parent compounds and comprehensive mitigation of the ecotoxicity potential. VUV/UVC represent an attractive oxidation technology for abatement QACs in contaminated water because the process does not require addition of catalysts or precursors.

Effect of zinc-biochar composite aging on its physicochemical and ecotoxicological properties

The stability of Zn-biochar composites is determined by environmental factors, including the aging processes. This paper focused on the ecotoxicological evaluation of Zn-biochar (Zn-BC) composites subjected to chemical aging. Pristine biochars and composites produced at 500 or 700 °C were incubated at 60 and 90 °C for six months. All biochars were characterized in terms of their physicochemical (elemental composition, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and porous structure), ecotoxicological properties (tested with Folsomia candida and Aliivibrio fischeri) and contaminant content (polycyclic aromatic hydrocarbons (PAH), heavy metals (HM) and environmentally persistent free radicals (EPFR)). An increase in the number of surface oxygen functional groups and increased hydrophilicity and polarity of all Zn-BC composites were observed due to oxidation during aging. It was also found that Zn-BC aging at 90 °C resulted in a 28–30% decrease in solvent-extractable PAHs (Ʃ16 Ctot PAHs) compared to nonaged composites. The aging process at both temperatures also caused a 104 fold reduction in EPFRs in Zn-BC composites produced at 500 °C. The changes in the physicochemical properties of Zn-BC composites after chemical aging at 90 °C (such as pH and HM content) caused an increase in the toxicity of the composites to Folsomia candida (reproduction inhibition from 19 to 24%) and Aliivibrio fischeri (luminescence inhibition from 96 to 99%). The aging of composites for a long time may increase the adverse environmental impact of BC-Zn composites due to changes in physicochemical properties (itself and its interactions with pollutants) and the release of Zn from the composite.

Pharmaceuticals, hazard and ecotoxicity in surface and wastewater in a tropical dairy production area in Latin America

Pharmaceuticals comprise a complex group of emerging pollutants. Despite the significant number of pharmaceuticals used in veterinary medicine, the input of these compounds into the environment due to livestock activities has been scarcely described. This work assays for the first time in Central America the occurrence of pharmaceuticals in farm wastewater in an area devoted to dairy production, and in the surrounding surface waters. Among 69 monitored pharmaceuticals, a total of eight compounds were detected in wastewater samples collected from seven dairy farms after three sampling campaigns. Six pharmaceuticals were considered either of high (albendazole, lovastatin and caffeine) or intermediate estimated hazard (ciprofloxacin, acetaminophen and ketoprofen) based on the HQ approach, while 26% of the samples were considered of high estimated hazard according to the cumulative ∑HQ approach. Similarly, when ecotoxicological tests were applied, all the samples showed some level of toxicity towards Daphnia magna, and most samples towards Vibrio fischeri and Lactuca sativa. Fourteen pharmaceuticals were detected in surface water samples collected in the surroundings of the dairy production farms, including rural and urban areas. Seven out of these compounds showed high estimated risk (risperidone, diphenhydramine, trimethoprim, fluoxetine, ofloxacin, caffeine and ibuprofen), while three (gemfibrozil, ciprofloxacin and cephalexin) exhibited intermediate estimated risk. In a similar worrisome way, 27% of these samples were estimated to pose high environmental risk according to the pharmaceutical content. Despite being nontoxic for D. magna or V. fischeri, frequent inhibition (>20%) of GI in L. sativa was determined in 34% of surface water samples; such findings raise concern on the apparent inceptive environmental pollution and risk within the area. According to the pharmaceutical content patterns in both kinds of studied matrices, no clear evidence of significant contamination in surface water due to livestock activities could be retrieved, suggesting a main role of urban influence.

Study of the Chemical Composition and Biological Effects of Aromatic Waters in a Comparative Aspect

Introduction. Vegetable raw materials processing products are becoming very popular. Of particular value are the products of essential oil production – aromatic waters or hydrolates. Hydrolates are widely used as cosmetics because they contain a number of biologically active water-soluble components of essential oil, but unlike the latter they have a softer effect on the skin, which allows them to be used in their pure form.Aim. To study the chemical composition, antibacterial and antioxidant activity of hydrolates.Materials and methods. Hydrolates were used as objects of research of production JSC "AEMSZ" derived from plants: Lavandula angusifolia, Hyssоpus officinаlis, Sаlvia officinаlis, Rosmarinus officinalis, Rosa damascеna × Rosa gallica. The composition was analyzed by gas-liquid chromatography. Antibacterial properties of hydrolates were studied with the use of bioluminescent marine bacteria Aliivibrio fischeri F1 and recombinant test-bacteria Escherichia coli MG1655 (pXen7). The study of the antioxidant effect was carried out by the method of Fe3+-induced lipid peroxidation of egg lipoprotein suspension in vitro.Results and discussion. It was found that salvia hydrolate contains α- and β-thujone, β-caryophyllene, α-terpineol; lavender hydrolate – camphene, linalool, linalyl acetate, geraniol, geranyl acetate; rosemary hydrolate – camphene, 1,8-cineol, β-pinene; rose hydrolate – phenylethanol, geraniol, citronelol, nerol; hydrolate hyssop – pinocamphone, isopinocamphone, spatulenol, β-caryophyllene. The antibacterial properties of the studied hydrolates were manifested in the inhibition of test bacteria bioluminescence and growth. Hydrolates of hyssop, lavender and rosemary were characterized by the greatest activity, rose and salvia had a lesser effect. It was also shown that hyssop and lavender hydrolates exhibited the bactericidal properties. Through the studying the antioxidant effect, the dynamics of accumulation of products of free-radical oxidation of lipids was observed, which in the presence of hyssop and rosemary hydrolates decreased by 40 and 36 %, respectively, in comparison with the control.Conclusion. As a result of the research, it was found that the studied hydrolates have pronounced antibacterial properties. Antioxidant properties of Hyssopus officinalis and Rosmarinus officinalis hydrolates were also revealed. Prospects for further research are the development of medicinal and cosmetic products based on the hydrolates of the above-stated essential oil cultures.

Reaction mechanism, degradation pathway and toxicity assessment of NH4+ enhanced potassium ferrate removal of levofloxacin

Considering that ammonium ion (NH4+) was widely distributed in natural water and many sewage, it was of great practical significance to study NH4+ enhanced potassium ferrate (Fe(VI)) to rapid removal of levofloxacin (LEV) from water. In this experiment, firstly, the reaction kinetic of NH4+ enhanced Fe(VI) removal of LEV was studied, and the results showed that the enhanced removal reaction conformed to the second-order kinetic equation. When pH ≤ 9, the second-order rate constant kapp was linearly related to NH4+ dosage, but when pH= 10, the above linear relationship was broken, and the slope of the fitting line would change toward a smaller trend. Subsequently, tert-butanol (TBA) and Methyl phenyl sulfoxide (PMSO) were used as probes for·OH and high-valent iron-based intermediate (Fe(V)/Fe(IV)) respectively, which further revealed the reaction mechanism that NH4+ enhanced Fe(VI) to remove LEV as follows: NH4+ could promote Fe(VI) to produce a large amount of Fe(V)/Fe(IV), thus accelerating the degradation of LEV. In addition, 10 degradation intermediates of LEV were identified by quadrupole time-of-flight tandem ultra-performance liquid chromatography mass spectrometer (Q-TOF LC-MS), and then combined with density functional theory (DFT) calculation, two possible degradation pathways were inferred. Through the luminescence inhibition experiment of Vibrio fischeri and the toxicity evaluation of ECOSAR, it could be concluded that in the process of NH4+ enhancing Fe(VI) to remove LEV, the toxicity of the solution showed a trend of increasing first and then decreasing, and its toxicity was effectively improved and reduced after full oxidation. Finally, the experiments in actual water showed that it was feasible to use NH4+ in actual water to enhance Fe(VI) for rapid removal of LEV.

Environmental impacts of 5-year plastic waste deposition on municipal waste landfills: A follow-up study

Depositing plastic waste has long been a prevalent method of utilization, persisting today. Plastic waste within municipal waste landfills (MWL) undergoes diverse (bio-)degradation processes, which may be a potential source of chemicals and microorganisms harmful to the environment and human health. Soil and air samples were collected from modern MWL to identify environmental contamination caused by 5 years of plastic (bio-)degradation. The pH of soil samples was higher than in the reference area (RA), which was possibly caused by alterations in soil anionic composition detected with ion chromatography. The presence of plastic additives with a toxic potential was detected in soil samples by gas chromatography coupled with tandem mass spectrometry (GC–MS/MS). With the use of thermal desorption and GC – MS, hazardous substances (phthalic anhydride, phenylmaleic anhydride, ethylbenzene, xylene) with a known impact on the human endocrine system were also detected. The number of microorganisms, both fungi, and bacteria, was highly increased in soil and air in the MWL as compared to the RA. The soil collected in the MWL area appeared to be phytotoxic, and inhibited seed germination (Phytotoxkit FTM bioassay), while acute toxicity Microtox® bioassay showed a hormetic effect towards Aliivibrio fischeri. Obtained results exhibited massive soil and air contamination, with both chemical substances and microorganisms while plastic waste undergoes (bio-)degradation. It may contribute to serious environmental contamination and pose a threat to human health.

Modelled microgravity impacts Vibrio fischeri population structure in a mutualistic association with an animal host.

Perturbations to host-microbe interactions, such as environmental stress, can alter and disrupt homeostasis. In this study, we examined the effects of a stressor, simulated microgravity, on beneficial bacteria behaviours when colonising their host. We studied the bacterium Vibrio fischeri, which establishes a mutualistic association in a symbiosis-specific organ within the bobtail squid, Euprymna scolopes. To elucidate how animal-microbe interactions are affected by the stress of microgravity, squid were inoculated with different bacterial strains exhibiting either a dominant- or sharing-colonisation behaviour in High Aspect Ratio Vessels, which simulate the low-shear environment of microgravity. The colonisation behaviours of the sharing and dominant strains under modelled microgravity conditions were determined by counting light-organ homogenate of squids as well as confocal microscopy to assess the partitioning of different strains within the light organ. The results indicated that although the colonisation behaviours of the strains did not change, the population levels of the sharing strains were at lower relative abundance in single-colonised animals exposed to modelled microgravity compared to unit gravity; in addition, there were shifts in the relative abundance of strains in co-colonised squids. Together these results suggest that the initiation of beneficial interactions between microbes and animals can be altered by environmental stress, such as simulated microgravity.

Application of the Aliivibrio fischeri bacterium bioassay for assessing single and mixture effects of antibiotics and copper.

The Aliivibrio fischeri bioassay was successfully applied in order to evaluate the acute effect of sulfamethoxazole (SMX), ciprofloxacin (CIP), chlortetracycline (CTC) and copper (Cu), alone or in binary, ternary, and overall mixture. The toxicity results are reported in terms of both effective concentrations, which inhibited 50% of the bacterium bioluminescence (EC50%), and in Toxic Units (TUs). The TUs were compared with predicted values obtained using the Concentration Addition model (CA). Finally, the toxicity of water extracts from a soil contaminated by the three antibiotics (7mg Kg-1 each) in the presence/absence of copper (30mg Kg-1) was also evaluated. Copper was the most toxic chemical (EC50: 0.78mg L-1), followed by CTC (EC50: 3.64mg L-1), CIP (96mg L-1) and SMX (196mg L-1). Comparing the TU and CA values of the mixtures, additive effects were generally found. However, a synergic action was recorded in the case of the CIP+Cu co-presence and antagonistic effects in the case of CTC+Cu and the ternary mixture (containing each antibiotic at 0.7mg L-1), were identified. Soil water extracts did not show any toxicity, demonstrating the buffering ability of the soil to immobilize these chemicals.

An optimized electro-fenton pretreatment for the degradation and mineralization of a mixture of ofloxacin, norfloxacin, and ciprofloxacin

The electro-Fenton process (EFP) is a powerful advanced oxidation process beneficial to treating recalcitrant contaminants, and there has been a continuing interest in combining this technology to enhance the efficiency of conventional wastewater treatment processes. In this work, an optimized EFP process is performed as pretreatment for the degradation and mineralization of three blank fluoroquinolones (FQs) drugs: ofloxacin (OFL), norfloxacin (NOR), and ciprofloxacin (CIP). The optimization of the experiment was carried out using a Box-Behnken experimental design. Faster and complete degradation of the drugs mixture was achieved in 90 min with 61.12 ± 2.0% of mineralization in 180 min, under the optimized conditions: j = 244.0 mA cm−2, [Fe2+] = 0.31 mM, and [FQs] = 87.0 mg L−1. Furthermore, a low toxicity effluent was obtained in 90 min of the experiment, according to bioassay toxicity with Vibrio fischeri. Five short-chain carboxylic acids, including oxalic, maleic, oxamic, formic, and fumaric acids, were detected and quantified, in addition to F− and NO3− inorganic ions. The inhibition of the reactive oxygen species with scavenger proof was also evaluated in this paper.

A hybrid anaerobic osmotic membrane bioreactor - membrane distillation for water reclamation: aquatic toxicity, membrane fouling characterization, and economic assessment

The incomplete removal of pharmaceutically active compounds (PhACs) by conventional wastewater treatment has been challenging due to their ecological implications. Therefore, advanced technologies are necessary to remove PhACs efficiently. In the present study, an anaerobic osmotic membrane bioreactor - membrane distillation (AnOMBR-MD), aiming to remove seven PhACs, was evaluated by an integrated approach, considering the environmental toxicity, fouling characterization, and economic assessment. PhACs removal was evaluated using liquid chromatography coupled with mass spectrometry. Besides, organic matter and nutrient removal were evaluated. The FO and MD membrane fouling was characterized with scanning electron microscopy and energy dispersive spectroscopy. Toxic effects were analyzed for Aliivibrio fischeri, Daphnia similis, and Raphidocelis subcapitata. Furthermore, a preliminary economic assessment was carried out using capital and operating expenditures. The results showed a DOC, N-NH4+, and P-PO43- removal of 92%, 97%, and 99.9%, respectively, while removal of PhACs was >96%. However, the distillate was classified as very toxic forR. subcapitata, and a strong correlation was found between toxicity and the Mg2+ originating from the draw solution (DS). This result showed the importance of including toxicity tests in the selection of DS. The economic evaluation indicated that the higher cost is related to the membrane replacement due to the decrease in the permeate flux, pointing out the need for future studies that address cleaning strategies to solve the organic and inorganic fouling on the membrane's surface. In this sense, this study promoted an improvement in understanding the AnOMBR-MD technical-economic viability aiming at full-scale application.

Eluates from façades at the beginning of their service time affect aquatic and sediment organisms

Biocides are used in building materials to prevent microbial growth during storage (in-can preservatives) as well as after application (film preservatives). These compounds can leach out from the material into the environment and harm non-target organisms. In this study, the ecotoxicological effect of leachates at the beginning of a façade lifetime, on sediment and aquatic organisms was examined. For this purpose, leaching tests were carried out in the setting of a natural weathering experiment and a laboratory immersion with façade samples consisting of render/paint systems. The leaching experiments were performed with three different formulations, namely no biocides containing control, a formulation containing only in-can preservatives (benzisothiazolinone (BIT), methylchloroisothiazolinone (CMIT), and methylisothiazolinone (MIT)), and, as is common in organic building materials, containing both in-can and film preservatives (octylisothiazolinone (OIT) and terbutryn (TB)). In order to elucidate the effects of in-can and film preservative-containing eluates the toxicity of the generated leachables was evaluated on the model of several aquatic and sediment organisms, namely luminescent bacteria (Vibrio fischeri), green algae (Scenedesmus subspicatus), Salmonella typhimurium TA1535/pSK1002 (umu-test), fish-egg (Danio rerio), Chironomus riparius, and Lumbriculus variegatus. It was demonstrated that in-can preservatives leach out rapidly at the beginning of a façade lifetime and despite the short half-life of these compounds in aqueous solutions, they could be detected at high concentrations in the eluates. Furthermore, eluates from early sampling times, predominantly containing in-can preservatives, were found to cause toxic effects on sediment and aquatic organisms. The results demonstrate that in-can preservatives can impose a significant stress factor on the environment.

Comparative analysis of the capability of the extended biotic ligand model and machine learning approaches to predict arsenate toxicity

Assessment of inorganic arsenate (As(V)) is critical for ensuring a sustainable environment because of its adverse effects on humans and ecosystems. This study is the first to attempt to predict As(V) toxicity to the bioluminescent bacterium Aliivibrio fischeri exposed to varying As(V) dosages and environmental factors (pH and phosphate concentration) using six machine learning (ML)-guided models. The predicted toxicity values were compared with those predicted using the extended biotic ligand model (BLM) we previously developed to evaluate the toxic effect of oxyanion (i.e., As(V)). The relationship between the variables (input features) and toxicity (output) was found to play an important role in the prediction accuracy of each ML-guided model. The results indicated that the extended BLM had the highest prediction accuracy, with a root mean square error (RMSE) of 12.997. However, with an RMSE of 14.361, the multilayer perceptron (MLP) model exhibited quasi-accurate prediction, despite having been trained with a relatively small dataset (n = 256). In view of simplicity, an MLP model is compatible with an extended BLM and does not require expert knowledge for the derivation of specific parameters, such as binding fraction and binding constant values. Furthermore, with the development and employment of reliable in-situ sensing techniques, monitoring data are expected to be augmented faster to provide sufficient training data for the improvement of prediction accuracy which may, thus, allow it to outperform the extended BLM after obtaining sufficient data.

Sociomicrobiology: Coexistence of conflict and cooperation in the squid light organ

The Hawaiian bobtail squid's Vibrio fischeri symbionts use quorum sensing for both bioluminescence and to modulate antagonism. New research finds quorum sensing unexpectedly represses V.fischeri's type 6 secretion system, highlighting intricate connections between cooperative and competitive microbial behaviors.

Estrogenic activity and acute toxicity assessments of sediments from a chronically polluted estuarine area in southeastern Brazil

AbstractCompounds displaying estrogenic potential can lead to serious negative aquatic ecosystem impacts, and exposure to mixtures of endocrine disruptors present in environmental matrices with very complex characteristics, including sediments, can cause serious risks to biota, animals, and humans. Within this perspective, the aim of the present study was to assess estrogenic activity and toxicity in sediments sampled from Guanabara Bay, the most important, although chronically polluted, estuary in southeastern Brazil. To this end, estrogenic activity determinations were performed by the yeast estrogen screen (YES) assay, and acute toxicity assays were carried out employing Vibrio fischeri. Estrogenic activity was quantified up for 8.7 ng g−1 in E2‐EQ, although high levels of cytotoxicity (up to 95%) were observed and might have hindered the determination of the real estrogenic potential in most samples. Acute toxicity to V. fischeri ranged from 0 to 45.21%. These results point to potential deleterious effects caused by micropollutants and underline the urgency of continuous monitoring of the degradation degree of the Guanabara Bay estuary.

Applicability of NH2-MOF235(Fe)-derived α-Fe2O3/ZnO photocatalyst synthesized by the microwave-assisted method in the degradation of a mixture of phenolic compounds

The NH2-MOF235(Fe)-derived α-Fe2O3-X%/ZnO (X = 15, 20, and 25 wt%) composites were successfully synthesized by microwave-assisted method followed by calcination at 450 °C. The materials were evaluated on the photocatalytic degradation of bisphenol A (BPA), 4-tert-butylphenol (4tBP), and 4-tert-octylphenol (4tOP) mixture (5 mg/L, each) under solar simulated radiation. The synthesized materials were characterized by XRD, FTIR, N2 physisorption analysis, SEM-EDS, XPS, and electrochemical assays. The NH2-MOF235(Fe)-derived α-Fe2O3 incorporation during the ZnO synthesis led to an increase in the specific surface area, improved light absorption in the visible region of the spectrum, and efficient separation of photogenerated charges. Based on the face-centered central composite experimental design matrix and RSM (response surface methodology), the optimal conditions for mineralization of the endocrine-disrupting compound mixture (42.52%) were reached using α-Fe2O3-15%/ZnO photocatalyst at pH 7.0 in 330 min (600 kJ m−2 of accumulated radiation). Moreover, 85.33, 92.82, and 92.72% degradation percentages were obtained for 4tBP, 4tOP, and BPA, respectively. Acetic acid and 2,4-di-tert-butylphenol were the main detected by-products at the end of the treatment. The α-Fe2O3-15%/ZnO material was stable for three reuse cycles for the photocatalytic degradation of the endocrine-disrupting compounds mixture. The scavenger study showed that the O2●- followed by the ●OH radical and photogenerated h+ were the main reactive species involved in the degradation of the contaminants mixture. The Vibrio fischeri assay showed that the obtained effluent was non-toxic. NH2-MOF235(Fe)-derived α-Fe2O3 improves the properties of ZnO, resulting in a promising material to eliminate BPA, 4tBP, and 4tOP mixture from aqueous samples.

Vibrio gazogenes-dependent disruption of aflatoxin biosynthesis in Aspergillus flavus: the connection with endosomal uptake and hyphal morphogenesis.

Aflatoxins, a family of fungal secondary metabolites, are toxic and carcinogenic compounds that pose an enormous threat to global food safety and agricultural sustainability. Specifically agricultural products in African, Southeast Asian and hot and humid regions of American countries suffer most damage from aflatoxin producing molds due to the ideal climate conditions promoting their growth. Our recent studies suggest that Vibrio gazogenes (Vg), an estuarine bacterium non-pathogenic to plants and humans, can significantly inhibit aflatoxin biosynthesis in the producers. In this study, we investigated the mechanism underlying Vg-dependent aflatoxin inhibition using the prominent aflatoxin producer, Aspergillus flavus. We show that aflatoxin inhibition upon Vg treatment was associated with fungal uptake of Vg-prodigiosin, a red pigment, which was consistently visible inside fungal hyphae during treatment. The association of prodigiosin with aflatoxin inhibition was further evident as Serratia marcescens, another prodigiosin producer, significantly inhibited aflatoxin, while non-producers like Escherichia coli, Staphylococcus aureus, Vibrio harveyi, and Vibrio fischeri did not. Also, pure prodigiosin significantly inhibited aflatoxin biosynthesis. Endocytosis inhibitors, filipin and natamycin, reduced the Vg-prodigiosin uptake by the fungus leading to a significant increase in aflatoxin production, suggesting that uptake is endocytosis-dependent. The Vg treatment also reduced hyphal fusion (>98% inhibition) and branching, which are both endosome-dependent processes. Our results, therefore, collectively support our theory that Vg-associated aflatoxin inhibition is mediated by an endocytosis-dependent uptake of Vg-prodigiosin, which possibly leads to a disruption of normal endosomal functions.

Pharmaceuticals Removal by Ozone and Electro-Oxidation in Combination with Biological Treatment

This study investigated the efficiency of two advanced oxidation processes (AOPs), ozonation (O3), and electrochemical oxidation (EO), applied individually or in combination, in the removal of contaminants of emerging concern (CECs) contained in hospital wastewaters, focusing on pharmaceuticals. The optimisation of the single technologies was performed using synthetic wastewater composed of four refractory pharmaceuticals, (carbamazepine-CBZ, lorazepam-LZP, ketoprofen-KTP, 10,11-epoxicarbamazepine-E-CBZ), first alone and then in mixture, in an initial concentration of 1 mg L−1 each. Once the best operational conditions for EO and O3 were defined, their combination (both simultaneous and sequential) was evaluated for the mixture of the selected pharmaceuticals. The treatment solution that showed the best performance was the simultaneous combination of O3 and EO. This treatment was validated using real hospital wastewater previously treated through a moving bed biofilm reactor (MBBR), evaluating its viability by testing the toxicity of the final effluent via Vibrio fischeri inhibition tests. The obtained results showed that the simultaneous combination of O3 and EO as the polishing step after a biological treatment is a very promising solution for hospital wastewater treatment, allowing for obtaining a non-toxic effluent and full degradation of refractory compounds. The disinfection potential of the proposed AOP was also assessed by determining Escherichia coli inactivation potential.

Highly efficient S-scheme AgBr/BiOBr with visible light photocatalytic performance for carbamazepine degradation: Mechanism insight and toxicity assessment

As more and more pharmaceutically active compounds (PhACs) have been found in the aquatic environment in recent years, the risks they pose to human health cannot be neglected. In this work, an innovative S-scheme AgBr/BiOBr photocatalyst for carbamazepine (CBZ) degradation was synthesized using a simple precipitation approach. XRD, SEM, XPS, UV–vis, PL, TPR, and EIS were employed to analyze the samples' crystal structure, morphology, chemical state, optical, and electrochemical properties. The effectiveness of the photocatalyst was also demonstrated through experiments, where a removal efficiency of 99.64 % was achieved under visible light for CBZ degradation using AgBr/BiOBr 10 wt%. Furthermore, photocatalytic cycling experiments, XRD characterization and cation exposure tests revealed that as-prepared photocatalysts had high reusability and stability. The intermediates were identified by HPLC-MS to reveal the possible degradation pathways of CBZ. The biological toxicity of CBZ and its degradation intermediates was also evaluated using the Vibrio fischeri luminescent bacteriological method and the toxicological calculation software. The findings of quenching experiments and ESR analyses indicated that ·O2− and h+ were the principal reactive species. The photoelectron transfer mechanism of AgBr/BiOBr photocatalyst was proposed as well. Overall, the synthesized photocatalysts are promising to provide a new insights into CBZ removal in the aqueous environment.

Bioactivity profiles of six baobab fruit pulp powders via planar chromatography hyphenated with effect-directed analysis

Baobab (Adansonia digitata) fruit pulp has a high nutrient content and has been traditionally used for medicinal purposes (e.g., as an anti-inflammatory and antioxidant agent) that may help protect against chronic diseases. Six different baobab fruit pulp powders were investigated using three different extractants and analyzed by high-performance thin-layer chromatography (HPTLC) hyphenated with antibacterial bioassays and enzyme inhibition assays. The developed non-target effect-directed screening was performed after extraction with pentyl acetate – ethanol 1:1 (V/V) on the HPTLC plate silica gel 60 using toluene – ethyl acetate – methanol 6:3:1 (V/V/V) as mobile phase system and derivatization via the anisaldehyde sulfuric acid reagent for detection. The physico-chemical profiles of the six baobab fruit pulp powder extracts were comparable, although the intensity of some zones was moderately different. The following effect-directed profiling via tyrosinase, α-glucosidase, and acetylcholinesterase inhibition assays as well as antibacterial Aliivibrio fischeri and Bacillus subtilis bioassays revealed one prominent multipotent bioactive compound zone in common, more or less active in all five studied (bio)assays. Via the recording of high-resolution mass spectra, this compound zone was tentatively assigned to coeluting saturated (palmitic acid 16:0 and stearic acid 18:0), monounsaturated (oleic acid 18:1), and polyunsaturated (linoleic acid 18:2 and linolenic acid 18:3) fatty acids. This finding was confirmed by other studies, which already proved individual activities of fatty acids. The first (bio)activity profiling of baobab fruit pulp powders via HPTLC-effect-directed analysis revealed that the baobab fruit could be considered as a functional food, however, further research is needed to study the impact on health and the influences on the bioactivity arising from different climates, years and soils or regions.