Triphenylmethane dye (C52H54N4O12) is potentially a hazardous substance in edible freshwater fish at trace level: toxicity, hematology, biochemistry, antioxidants, and molecular docking evaluation study

Evaluation of Hepatotoxic Potential of an Azo Dye, Eriochrome Black T on Freshwater Catfish, Clarias batrachus

Nowadays, textile industries are one of the major contributors to water pollution, causing a devastating impact on aquatic ecosystems. Therefore, the current study aimed to investigate the impact of a textile azo dye, Eriochrome Black T (EBT), on the liver of a freshwater fish, Clarias batrachus. Fish were exposed to three concentrations of EBT, i.e., 1 mgL-1, 10 mgL-1 and 20 mgL-1, to evaluate oxidative stress markers such as level of lipid peroxidation (LPO) and activity of enzymatic antioxidants (SOD, CAT, GPx and GR), as well as histology and histochemitry following 96 h of exposure. The results revealed a significant increase (p < 0.05) in EBT bioaccumulation, resulting in elevated level of LPO and significant variation (p < 0.05) in the activities of antioxidant enzymes. The percent change calculation of oxidative stress markers of exposed fishes from control one showed that EBT had most significant impact on the fishes exposed to 20 mgL-1 of EBT. Histological and histochemical examinations also demonstrated the deteriorating impact of EBT on structural architecture of liver. Hence, the present study concludes that EBT causes detrimental impact on fish health by impairing its liver detoxification system and metabolism. Therefore, it is suggested to explore mechanism of EBT toxicity on aquatic organisms so that its hazardous risk can be monitored and preventive measures can be taken.

Impact of continuous Triazophos exposure on Labeo rohita: Physiological, biochemical, and histological alterations and IBRv2 index assessment

Pesticides are commonly used in agriculture and aquaculture. Triazophos, an organophosphate-based pesticide, is widely used in agriculture to control many insect pests. Due to its high photochemical stability and mode of action, Triazophos could persist in the aquatic ecosystem and cause toxic effects on non-target organisms. We have studied the potential toxic effects of Triazophos on L. rohita. Primarily, we determined the median lethal concentration (LC50) of Triazophos for 24 and 96 h. Next, we studied acute (96 h, LC50-96 h) toxicity. Then, we studied chronic (35 days, 1/10th LC50-24 h Treatment I: 0.609 mg/L, 1/5th LC50-96 h Treatment II: 1.044 mg/L) toxicity. We analyzed blood biomarkers such as hematology (Hb, Hct, RBC, WBC, MCV, MCH and MCHC), prolactin, cortisol, glucose and protein levels. Concurrently, we analyzed tissue biomarkers such as glycogen, GOT, GPT, LDH and histopathology. IBRv2 index assessment method was also to evaluate the Triazophos toxicity. Studied hematological, hormonal, biochemical and enzymological biomarkers were affected in Triazophos treated groups when compare to the control group. The changes in these biomarkers were statistically significant at the 0.05 alpha level. Triazophos exposed fish shown a severe degenerated primary and secondary lamellae, lamellar fusion, hypertrophy and telangiectasia in the gills. In the hepatic tissue, it caused moderate necrosis, blood congestion, distended sinusoids with minor vacuolation, prominent pyknotic nuclei, hypertrophy, cloudy swelling of cells, lipid accumulation and fibrotic lesions. In the renal tissue, Triazophos caused thickening of Bowman's capsule, hyaline droplets degeneration, irregular renal corpuscle, congestion, cellular swelling, degeneration of tubular epithelium, necrosis, shrunken glomerulus, vacuolated glomerulus, hypertrophy, exudate and edema. IBRv2 analysis suggested that tissue biomarkers are highly sensitive to Triazophos toxicity and prolonged exposure could cause serious health effects like acute toxicity in fish. Triazophos could cause multiorgan toxicity at studied concentrations.

Characterization and Degradation of Triphenylmethane Dyes and Their Leuco-Derivatives by Heterologously Expressed Laccase From Coprinus cinerea

Laccase is a copper-containing polyphenol oxidase that can oxidize phenolic and non-phenolic organic substrates. In the past decades, laccases had received considerable attention because of the ability to degrade various organic substances. Based on the codon preference of the Pichia pastoris expression system, this study optimized the gene structure of the laccase gene Lcc1 from Coprius cinerea through synthetic biology methods. A new gene Lcc1I was synthesized and heterologously expressed in P. pastoris. After 3 days of cultivation in a shake flask at 30°C, the transformants produced at a yield of 890 mg L-1protein. The highest production level of the recombinant laccase was 2760 U L-1. The molecular mass of the recombinant laccase was estimated at 60 kDa. The enzyme showed highest activity at pH 3.4 and 45°C. It possessed better stability at higher pH and lower temperature condition. Using 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulphonate (ABTS) as the substrate, the Km and Vmax values were 0.136 mM and 9778 μM min-1 mg-1, respectively. The recombinant laccase could directly oxidize some triphenylmethane dyes like leuco-crystal violet (LCV) and leuco-malachite green (LMG). With the help of ABTS mediator, it could oxidize and degrade 77.7% crystal violet (CV) and 79.2% malachite green (MG) within 1 h. Our results indicate that optimization of the laccase gene achieves good expression results in the host system. The dye degradation model constructed in this study may also be applied to the degradation of other organic pollutants and toxic substances, providing new solutions for environmental remediation against the increasingly severe environmental pollution.

rGO/ZIF-8 Aerogel for Effective Removal of Malachite Green from Wastewater

In this study, dopamine-modified graphene aerogel (DGA) is synthesized through a one-step hydrothermal method using graphene oxide as the precursor and dopamine as the reducing agent. Subsequently, in situ immersion synthesis is conducted to obtain ZIF-8 loaded on a dopamine-modified graphene aerogel skeleton (ZDGA), featuring a regular honeycomb interconnected mesoporosity and a high specific surface area of 532.8 m2/g. The synthesized ZDGA exhibited exceptional adsorption performance for the cationic dye malachite green. At room temperature, ZDGA achieved an impressive equilibrium adsorption capacity of 6578.34 mg/g. The adsorption process followed pseudo-secondary kinetics and adhered to the Langmuir model, indicating chemically dominated adsorption on a monomolecular layer. Intraparticle diffusion was the primary rate determinant, with π-π stacking, electrostatic adsorption, hydrogen bonding, and Lewis acid-base interactions serving as the key driving forces. It has an ideal specific surface area and good cycling performance, which highlights its potential application in dye wastewater treatment.

Engineering Site 228 of Streptomyces coelicolor Laccase for Optimizing Catalytic Activity

Malachite green (MG) poses a formidable threat to ecosystems and human health. Laccase emerges as a promising candidate for MG degradation, prompting an investigation into the catalytic activity modulation of a small laccase (SLAC) from Streptomyces coelicolor, with a focus on amino acid position 228. Through saturation mutagenesis, five mutants with a 50% increase in the specific activity were generated. Characterization revealed notable properties, Km of E228F was 8.8% of the wild type (WT), and E288T exhibited a 133% kcat compared to WT. Structural analyses indicated improved hydrophobicity and electrostatic potential on the mutants' surfaces, with the stable E228F-ABTS complex exhibiting reduced flexibility, possibly contributing to the observed decrease in turnover rate. Mutants demonstrated enhanced MG decolorization, particularly E228G. Site 228 acts as a crucial functional control switch, suggesting its potential role in SLAC engineering. This study provides insights into laccase modulation and offers promising avenues for enzymatic bioremediation applications.