Due to the large-scale outbreak of Corona Virus Disease (2019), amounts of disinfecting agents was regularly used in public environments and their potential toxicity towards organisms needed to be appreciated. Thus, one mostly used cationic disinfectant, benzalkonium chlorides (BAC(C12)), was selected to assess its potential toxicity one common cyanobacteria Microcystis aeruginosa (M. aeruginosa) in this study. The aims were to explore the toxic effect and mechanism of BAC (C12) on M. aeruginosa growth within 96 h via morphological, physiological, and the relative and absolute quantification (iTRAQ)-based quantitative proteomics variations. The results found that BAC(C12) significantly inhibited cell density of M. aeruginosa at concentrations from 1 mg/L to 10 mg/L, and the 96-h EC₅₀ value was identified to be 3.61 mg/L. Under EC₅₀ concentration, BAC(C12) depressed the photosynthesis activities of M. aeruginosa exhibited by 36% decline of the maximum quantum yield for primary photochemistry (Fv/Fm) value and denaturation of photosynthetic organelle, caused oxidative stress response displayed by the increase of three indexes including superoxide dismutase (SOD), malondialdehyde (MDA), and the intracellular reactive oxygen species (ROS), and destroyed the integrity of cell membranes demonstrated by TEM images and the increase of ex-cellular substances. Then, the iTRAQ-based proteomic analysis demonstrated that BAC(C12) depressed photosynthesis activities through inhibiting the expressions of photosynthetic protein and photosynthetic electron transport related proteins. The suppression of electron transport also led to the increase of superoxide radicals and then posed oxidative stress on cell. Meantime, the 63.63% ascent of extracellular microcystin production of M. aeruginosa was observed, attributing to the high expression of microcystin synthesis proteins and the damage of cell membrane. In sum, BAC(C12) exposure inhibited the growth of M. aeruginosa mainly by depressing photosynthesis, inducing oxidative stress, and breaking the cell membrane. And, it enhanced the release of microcystin from the cyanobacterial cells via up-regulating the microcystin synthesis proteins and inducing the membrane damage, which could enlarge its toxicity to aquatic species.

Systemic studies on the bioremediation of co-contaminated PAHs and heavy metals are lacking, and this paper provides an in-depth review on the topic. The released sources and transport of co-contaminated PAHs and heavy metals, including their co-occurrence through formation of cation-π interactions and their adsorption in soil are examined. Moreover, it is investigated that co-contamination of PAHs and heavy metals can drive a synergistic positive influence on bioremediation through enhanced secretion of extracellular polymeric substances (EPSs), production of biosynthetic genes, organic acid and enzymatic proliferation. However, PAHs molecular structure, PAHs-heavy metals bioavailability and their interactive cytotoxic effects on microorganisms can exert a challenging influence on the bioremediation under co-contaminated conditions. The fluctuations in bioavailability for microorganisms are associated with soil properties, chemical coordinative interactions, and biological activities under the co-contaminated PAHs-heavy metals conditions. The interactive cytotoxicity caused by the emergence of co-contaminants includes microbial cell disruption, denaturation of DNA and protein structure, and deregulation of antioxidant biological molecules. Finally, this paper presents the emerging strategies to overcome the bioavailability problems and recommends the use of biostimulation and bioaugmentation along with the microbial immobilization for enhanced bioremediation of PAHs-heavy metals co-contaminated sites. Better knowledge of the bioremediation potential is imperative to improve the use of these approaches for the sustainable and cost-effective remediation of PAHs and heavy metals co-contamination in the near future.

In this study, the contents of microcystin-LR (MC-LR) of Microcystis aeruginosa cultures in the laboratory and natural water samples from the Huangpu River in different seasons were detected through enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC), respectively. Excellent correlation between the two methods was obtained (R² > 0.99). ELISA was a reliable and simple method with high reproducibility (coefficient of variation < 25%) and satisfactory recovery for the monitoring of low levels of MC-LR. MC-LR concentrations in Huangpu River varied with the seasonal variation, which peaked in August with the temperature over 30 °C and then gradually declined with the decreasing temperature after August. The highest MC-LR concentration in the Huangpu River was below the WHO drinking water quality standard (1 µg/L). These results indicated that warm temperature accelerated the MC-LR synthesis and release, and it is necessary to regularly monitor the MC-LR levels, especially during the high algae period in summer. ELISA can be applied to detect the low levels of MC-LR in the field without complex treatment, avoiding the samples from denaturation and degradation during the transportation. Hence, ELISA is a better alternative of HPLC when HPLC is unavailable, especially when rapid testing is required in routine MC-LR analysis.

Collagen is a promising candidate for food and pharmaceutical applications due to its excellent biocompatibility, low antigenicity, and controlled biodegradability; however, its heavy price restricts its utilization. Fish scales generated during the processing are generally regarded as waste material and an environmental pollutant, though they are a promising source of collagen. In the present study, Cirrhinus mrigala scales were demineralized and extracted for acid-soluble collagen (ASC) using acetic acid, with a collagen yield of 2.7%. UV–Vis spectra, SDS-PAGE, FTIR analyses, and amino acid composition confirmed the type I nature of the collagen extracted. The denaturation temperature of the collagen was found to be 30.09 °C using differential scanning calorimetry (DSC). The collagen was highly soluble at acidic pH and lower NaCl concentrations while its solubility was lowered in alkaline conditions and NaCl concentrations above 0.5 M. The collagen exhibited good emulsifying potential with an emulsion activity index (EAI) and emulsion stability index (ESI) of 21.49 ± 0.22 m² g⁻¹ and 15.67 ± 0.13 min, respectively. Owing to the good physicochemical characteristics of the extracted collagen, collagen-chitosan-neem extract (CCN) films were prepared subsequently which showed good antimicrobial activity against Bacillus subtilis NCIM 2635, Staphylococcus aureus NCIM 2654, Escherichia coli NCIM 2832, and Pseudomonas aeruginosa NCIM 5032, suggesting the potential of collagen in the development of antimicrobial films. These results demonstrate that the collagen from fish waste could be valorized and used effectively along with chitosan and neem extract for the synthesis of novel biodegradable films with antimicrobial efficacy.

Use of sodium chloride to preserve animal skins and hides is becoming increasingly untenable due to stringent environmental regulations. In the present research work, a combination of sparingly soluble alkali and water-soluble polymer of ethylene oxide has been used to preserve skins with an objective of total elimination of common salt for preservation. A comprehensive study has been made for evaluating various parameters, such as dehydration and rehydration behaviours of skins, microbial growth, emission loads and physico-chemical characteristics of the cured skin to validate the salt-free preservation system developed. The shrinkage temperature, denaturation temperature and mechanical strength of tanned leather were analysed by using shrinkage, differential scanning calorimetric and thermomechanical analysis techniques. The new curing system has been found to be effective in preserving the skin as indicated by the various parameters studied and the final leather quality. The significant reduction in total solids content such as dissolved solids and suspended solids present in the effluent compared to conventional preservation method is evident from environmental impact assessment studies.

Essential oils have recognized antimicrobial and antifungal properties which allow their utilization in agriculture like an alternative to pesticides, but their utilization requires the knowledge of all the potential structural changes and damages produced by the interaction with the vegetal organisms. In this paper, we investigated the effects of two essential oils, the tea tree oil (TTO) and the mixture of clove and rosemary oils (C + R), on the molecular structure of Vicia faba roots by Fourier transform infrared (FTIR) and Fourier near infrared transform (FTNIR) spectroscopy. FTIR spectroscopy showed structural modifications of the absorption bands related to DNA (1100 and 1050 cm⁻¹, carbohydrate backbones, and nucleotide bands within 900 and 850 cm⁻¹), proteins (1700 and 1600 cm⁻¹ amide I band, 1580 and 1520 cm⁻¹ amide II band), and lipids (methylene group of aliphatic chains between 2950 and 2800 cm⁻¹). The changes in the secondary structures of proteins consisted of a denaturation depending on increased presence of random coil structures. In addition, in the samples treated with TTO oils, we observed the presence of protein oxidation, an effect negligible instead for the C + R-treated samples. The modified shapes of the infrared methyl bands of aliphatic chains suggested an increased lipid disorder which could also determine lipid peroxidation. The changes observed for the DNA structures at the highest concentration of the above essential oils can be related to the genotoxic effect of eugenol, an important constituent of both TTO and C + R mixture oils. FTNIR spectroscopy showed the modified shape of the second overtone bands belonging to methyl and methylene groups, between 8500 and 8000 cm⁻¹. This confirmed the increased lipid disorders already observed by FTIR spectroscopy. The results obtained on the probe organism V. faba show that FTIR and FTNIR spectroscopy can become a useful support to the conventional cytogenetic tests used in the evaluation of the allelopathic uses of essential oils in agriculture.

The present work is to evaluate the neurotoxicity induced by pyrethroid insecticide “Deltamethrin” at 0.32 mg/kg/day in two main regions of the Wistar rat brain (hippocampus and striatum) and the protective effects of Quercetin at 10 mg/kg/day on this toxicity after 90 days of exposure. The assay of brain parameters showed that Deltamethrin caused a significant increase of mitochondrial metabolite level (proteins, lipids, and carbohydrates) and enzyme activity (glutathione S-transferase and superoxide dismutase); a decreased amount of mitochondrial glutathione level and catalase and glutathione peroxidase activities; and an increase of malondialdehyde (MDA) acid levels of the two regions. Furthermore, mitochondrial functional testing in the brains of treated rats exhibited a significant increase in permeability followed by a mitochondrial swelling. Instead, a statistically significant decrease in mitochondrial respiration (O₂ consumption) was recorded in the striatum and hippocampus. Our study showed that the pesticide caused a significant increase of the cytochrome c amount correlated with activation of neuronal apoptosis mechanisms by the significant increase of caspase-3 of hippocampus and striatum. In particular, the results of behavioral tests (open field, classic maze tests of sucrose, and Morris water maze) have significant changes, namely bad behavior of the treated rats, affecting the level of anxiety, learning, and memory, and general motor activity has mainly been shown in treated rats. In addition, the histological cuts clearly confirm cerebral necrosis in the hippocampus and the striatum caused by the pesticide. They allow us to consider the necrotic areas, black spots, reduction, and denaturation of these brain regions in the treated rats. On the other hand, we have studied the protective effects against the neurotoxicity of Deltamethrin (DLM). In this context, after the gavage of Quercetin at the dose of 10 mg/kg/day, we have noticed an improvement in the entire parameters: mitochondrial enzyme, metabolic, histological, and behavioral parameters. This confirmed the improvement of preventive and curative effect of Quercetin against free radicals induced by the DLM.

Click chemistry approaches are tailored to generate molecular building blocks quickly and reliably by joining small units together selectively and covalently, stably and irreversibly. The vegetable tannins such as hydrolyzable and condensed tannins are capable to produce rather stable radicals or inhibit the progress of radicals and are prone to oxidations such as photo and auto-oxidation, and their anti-oxidant nature is well known. A lot remains to be done to understand the extent of the variation of leather stability, color variation (lightening and darkening reaction of leather), and poor resistance to water uptake for prolonged periods. In the present study, we have reported click chemistry approaches to accelerated vegetable tanning processes based on periodates catalyzed formation of oxidized hydrolysable and condensed tannins for high exhaustion with improved properties. The distribution of oxidized vegetable tannin, the thermal stability such as shrinkage temperature (T ₛ) and denaturation temperature (T d), resistance to collagenolytic activities, and organoleptic properties of tanned leather as well as the evaluations of eco-friendly characteristics were investigated. Scanning electron microscopic analysis indicates the cross section of tightness of the leather. Differential scanning calorimetric analysis shows that the T d of leather is more than that of vegetable tanned or equal to aldehyde tanned one. The leathers exhibited fullness, softness, good color, and general appearance when compared to non-oxidized vegetable tannin. The developed process benefits from significant reduction in total solids and better biodegradability in the effluent, compared to non-oxidized vegetable tannins.

The collagens (COL2, COL4, and COL5) were extracted from chrome-tanned leather shavings via three distinctive routes of acid method. The dechroming degree of COL2 extracted with the easiest operation was the highest (95.6% ± 1.2%) and the yield exceeded 90%; however, the total amount of acid was the most and the cost was the highest. In the second route, although the three-step dechroming process brought cumbersome operation, the dechroming degree and yield of COL4 were 90.5% ± 0.8% and 92.2% ± 0.6%, respectively, and the acid amount was less than that in the first route. For COL5, the dechroming degree and yield was the lowest; nevertheless, this route had the advantages of lowest cost and simpler operation. Electrophoretic patterns showed that all the collagens contained α1, α2, and β chains without low molecular weight components and were close to those of type I collagen. Compared with native collagen extracted from fresh calf skin, the regenerated collagens also maintained unique triple helix conformation determined via ultraviolet, infrared spectra and X-ray diffraction, confirmed by the similar values of AIII/A₁₄₅₅ and Δν. Additionally, the collagens existed in the form of fibrils with D-period pattern of ~ 67 nm. Furthermore, the denaturation temperatures of COL2, COL4, and COL5 were 71.2, 79.1, and 85.4 °C, respectively, which were relevant to the tighter arrangement of fibrils with the increased chromium content.

As an alternative to bisphenol A, bisphenol S (BPS) is widely used in industrial production and daily life, which is then discharged into sewage treatment plants and accumulates in sludge. In this research, impact and interaction mechanism of BPS on lipids hydrolysis in sludge is studied from the respect of soluble organic matter and volatile organic fatty acids (VFAs). Multi-spectra, thermodynamics, molecule docking, and enzyme activity assay are applied to elucidate the effect mechanism of BPS on lipids hydrolysis. Results show that lipids hydrolysis is restrained due to the denaturation of lipase with BPS exposure. The interaction mechanism is involved in hydrophobic bond and hydrogen bond interaction in the activity region of lipase. This interaction not only results in an unfolding skeleton structure of lipase and a less hydrophobic microenvironment of tyrosine and tryptophan residues but also leads to fluorophore static quenching with the formation of lipase-BPS complex. The experimental results and the combined research methods not only contribute to the development of novel technique for sludge treatment containing micropollutant but also profit to clarify the interaction mechanism between other micropollutant and enzymes.