The gut microbiota: a new perspective on the toxicity of malachite green (MG)

Artificial neural network modelling and experimental investigations of malachite green adsorption on novel carboxymethyl cellulose/β-cyclodextrin/nickel cobaltite composite

This study presents a novel polymer nanocomposite based on carboxymethyl cellulose and β-cyclodextrin crosslinked with succinic acid (CMC-SA-β-CD) containing nickel cobaltite (NCO) nano-reinforcement. Various analytical techniques have been employed to investigate the structural, thermal, and morphological features of the resulting nanocomposite. The CMC-SA-β-CD/NCO nanocomposite has been utilized as an adsorbent for the removal of bisphenol-A (BPA, R% <40 %), malachite green (MG, R% > 75 %)), and Congo red (CR, no adsorption) from the synthetic wastewater. The study systematically explored the impact of various parameters on the adsorption process, and the interactions between MG and CMC-SA-β-CD/NCO were discussed. The adsorption data were fitted to different models to elucidate the kinetics and thermodynamics of the adsorption process. An artificial neural network (ANN) analysis was employed to train the experimental dataset for predicting adsorption outcomes. Despite a low BET surface area (0.798 m2 g-1), CMC-SA-β-CD/NCO was found to exhibit high MG adsorption capacity. CMC-SA-β-CD/NCO exhibited better MG adsorption performance at pH 5.5, 40 mg L-1 MG dye concentration, 170 min equilibrium time, 20 mg CMC-SA-β-CD/NCO dose with more than 90 % removal efficiency. Moreover, the thermodynamic studies suggest that the adsorption of MG was exothermic with ΔH° value -9.93 ± 0.76 kJ mol-1. The isotherm studies revealed that the Langmuir model was the best model to describe the adsorption of MG on CMC-SA-β-CD/NCO indicating monolayer surface coverage with Langmuir adsorption capacity of 182 ± 4 mg g-1. The energy of adsorption (11.4 ± 0.8 kJ mol-1) indicated chemisorption of MG on the composite surface. The kinetics studies revealed that the pseudo-first-order model best described the adsorption kinetics with q e  = 86.7 ± 2.9 mg g-1. A good removal efficiency (>70 %) was retained after five regeneration reuse cycles. The ANN-trained data showed good linearity between predicted and actual data for the adsorption capacity (R-value>0.99), indicating the reliability of the prediction model. The developed nanocomposite, composed predominantly of biodegradable material, is facile to synthesize and exhibited excellent monolayer adsorption of MG providing a new sustainable adsorbent for selective MG removal.

Dual-functional marine algal carbon-based materials with highly efficient dye removal and disinfection control

The design and simple, green preparation of dual-functional materials for the decontamination of both hazardous dyes and pathogenic microorganisms from wastewater remain challenging currently. Herein, a promising marine algal carbon-based material (named C-SA/SP) with both highly efficient dye adsorptive and antibacterial properties was fabricated based on the incorporation of sodium alginate and a low dose of silver phosphate via a facile and eco-friendly approach. The structure, removal of malachite green (MG) and congo red (CR), and their antibacterial performance were studied, and the adsorption mechanism was further interpreted by the statistical physics models, besides the classic models. The results show that the maximum simulated adsorption capacity for MG reached 2798.27 mg/g, and its minimal inhibit concentration for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was 0.4 mg/mL and 0.2 mg/mL, respectively. The mechanistic study suggests that silver phosphate exerted the effects of catalytic carbon formation and pore formation, while reducing the electronegativity of the material as well, thus improving its dye adsorptive performance. Moreover, the MG adsorption onto C-SA/SP showed vertical orientation and a multi-molecular way, and its adsorption sites were involved in the adsorption process with the increase of temperature. Overall, the study indicates that the as-made dual-functional materials have good applied prospects for water remediation.

Malachite green and leucomalachite green in fish: a global systematic review and meta-analysis

Malachite green (MG), an antibiotic with antifungal activity, is illegally used in aquaculture. Given that this chemical is teratogenic and mutagenic, abstinence from intake seems to be a need for public safety. The goal of this systematic review and meta-analysis was to determine the global contamination of fishes by MG and its reduced metabolite, leucomalachite green (LMG), in a number of marine and farmed fish species. For literature published prior to January 2022, several databases (Web of Science, PubMed, and Scopus) were investigated. In total, 20 publications (10 countries, 724 samples) achieved the criteria for inclusion. The overall average MG and LMG concentrations were 0.48 (95% CI: 0.47, 0.49 µg kg^-1) and 0.59 (95% CI: 0.39, 0.79 µg/kg^-1), respectively. Eel (M. albus) 15.50 (95% CI: (14.39, 45.39 µg kg^-1) and eel (A. anguilla) 4.46 (95% CI: 1.23, 7.69 µg kg^-1) had the greatest contamination of MG and LMG, according to the effect size, respectively. Warm-water fish had a concentration of 2.591 (95% CI: 2.25, 2.93 µg kg^-1) while cold-water fish had a concentration of 1.55 (95% CI: 0.25, 2.84 µg kg^-1). Fish containing medium-fat level of 1.86 (95% CI: 1.27, 2.44 µg kg^-1) and high-fat content of 1.10 (95% CI: 0.93, 1.26 µg kg^-1) had accumulate MG and LMG in their tissues, respectively. As a result, total MG observed in countries including China, Iran, and the Netherlands was higher than authorized (2 µg kg^-1). The toxicity of MG and LMG demands more monitoring, especially in countries where these chemicals' residues are significant.

Multiple perspectives reveal the gut toxicity of polystyrene microplastics on Eisenia fetida: Insights into community signatures of gut bacteria and their translocation

The gut is the primary pathway by which soil animals are exposed to microplastics (MPs). However, the gut toxicity of MPs has not been elucidated in earthworms. Herein, we aimed to study the gut toxicity (e.g., gut barrier dysfunction, gut bacterial translocation, and pathogen invasion) of polystyrene microplastics (PS-MPs) on Eisenia fetida and its relationship with gut bacteria. We found that PS-MPs exposure caused gut barrier damage to Eisenia fetida. This damage included apparent injury of gut epithelial cells and significantly lower transcription levels of genes coding for gut tight junction (TJ)-related proteins. We then observed significantly increased levels of bacterial lipopolysaccharide (LPS) and gut bacterial load, indicating the occurrence of gut bacterial translocation and related barrier damage. Subsequently, antibacterial immune responses were activated and accompanied by a failure of the antioxidant defense system, indicating that pathogen invasion might occur. Gut barrier damage could weaken host selective pressures (deterministic process) on gut bacteria, such as particular pathogens. Indeed, members of Proteobacteria, e.g., Aeromonas and Escherichia/Shigella, regarded as potential opportunistic pathogens, were remarkable signatures of groups exposed to PS-MPs. These potential opportunistic gut bacteria were pivotal contributors to gut TJ damage and gut bacterial translocation resulting from PS-MPs exposure. In addition, the gut bacterial networks of PS-MPs exposure groups were more uncomplicated than those of the control group, but more negative interactions were easy to observe. In conclusion, our work sheds light on the molecular mechanism of earthworm gut toxicity caused by PS-MPs exposure and provides a prospective risk assessment of MPs in soil ecosystems.

Role-Playing Between Environmental Pollutants and Human Gut Microbiota: A Complex Bidirectional Interaction

There is a growing interest in the characterization of the involvement of toxicant and pollutant exposures in the development and the progression of several diseases such as obesity, diabetes, cancer, as well as in the disruption of the immune and reproductive homeostasis. The gut microbiota is considered a pivotal player against the toxic properties of chemicals with the establishment of a dynamic bidirectional relationship, underlining the toxicological significance of this mutual interplay. In fact, several environmental chemicals have been demonstrated to affect the composition, the biodiversity of the intestinal microbiota together with the underlining modulated metabolic pathways, which may play an important role in tailoring the microbiotype of an individual. In this review, we aimed to discuss the latest updates concerning the environmental chemicals–microbiota dual interaction, toward the identification of a distinctiveness of the gut microbial community, which, in turn, may allow to adopt personalized preventive strategies to improve risk assessment for more susceptible workers.

Toxicology and Microbiota: How Do Pesticides Influence Gut Microbiota? A Review

In recent years, new targets have been included between the health outcomes induced by pesticide exposure. The gastrointestinal tract is a key physical and biological barrier and it represents a primary site of exposure to toxic agents. Recently, the intestinal microbiota has emerged as a notable factor regulating pesticides’ toxicity. However, the specific mechanisms related to this interaction are not well known. In this review, we discuss the influence of pesticide exposure on the gut microbiota, discussing the factors influencing gut microbial diversity, and we summarize the updated literature. In conclusion, more studies are needed to clarify the host–microbial relationship concerning pesticide exposure and to define new prevention interventions, such as the identification of biomarkers of mucosal barrier function.

Stingless bee honey, a novel source of trehalulose: a biologically active disaccharide with health benefits

Stingless bee (Meliponini) honey has long been considered a high-value functional food, but the perceived therapeutic value has lacked attribution to specific bioactive components. Examination of honey from five different stingless bee species across Neotropical and Indo-Australian regions has enabled for the first time the identification of the unusual disaccharide trehalulose as a major component representing between 13 and 44 g per 100 g of each of these honeys. Trehalulose is an isomer of sucrose with an unusual α-(1 → 1) glucose-fructose glycosidic linkage and known acariogenic and low glycemic index properties. NMR and UPLC-MS/MS analysis unambiguously confirmed the identity of trehalulose isolated from stingless bee honeys sourced across three continents, from Tetragonula carbonaria and Tetragonula hockingsi species in Australia, from Geniotrigona thoracica and Heterotrigona itama in Malaysia and from Tetragonisca angustula in Brazil. The previously unrecognised abundance of trehalulose in stingless bee honeys is concrete evidence that supports some of the reported health attributes of this product. This is the first identification of trehalulose as a major component within a food commodity. This study allows the exploration of the expanded use of stingless bee honey in foods and identifies a bioactive marker for authentication of this honey in associated food standards.

Biomimetic detoxifier Prunus cerasifera Ehrh. silver nanoparticles: innate green bullets for morbific pathogens and persistent pollutants

Silver nanoparticles were fabricated in the presence and absence of light with silver nitrate and aqueous extract of Prunus cerasifera leaf via facile and one-pot green method. P. cerasifera leaf extract reduced and stabilized the nanoparticles with phytometabolites expunging the need for addition of external reducing agents. Optimized silver nanoparticle syntheses was done with variations in leaf extract concentration, time, temperature, and molarity for deciphering the photocatalytic, antifungal, and antibacterial potential of synthesized nanoparticles. Optical, compositional, and morphological analyses of the synthesized nanoparticles were done by UV-visible spectrometry (UV-Vis), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Formation of silver nanoparticles was confirmed firstly through UV-Vis by exhibition of peaks with 400-450 nm. FTIR confirmed the presence of major organic groups responsible for reduction of nanoparticles. AFM confirmed the spherical morphology of the synthesized nanoparticles with remarkable dispersion without any agglomeration. Phytochemical analysis for P. cerasifera leaf metabolites was done by GC-MS. Spherical nanoparticles having a size range of 57-144 nm were obtained with face-centered cubic crystals. The average crystallite size obtained from XRD spectra was 2.34 nm. Enhanced photocatalytic first-order kinetics were obtained for persistent organic pollutants, i.e., crystal violet, methylene blue, and malachite green (R² = 0.99, 0.99, 0.98) in less than 15 min. Biomedical and agricultural significance as an antibiotic drug and utilization as a fungicides substitute was explored against nine resistant microbes. Statistically significant variations were analyzed via one-way analysis of variance (ANOVA) and Kruskal-Wallis test and specific multi comparison tests. Active to highly active inhibition zones manifested the use of biogenic silver nanoparticles as potential candidate for applications in biological arenas and as environmental remediators.