Journal of Environmental Bioremediation and Toxicology

Bioremediation of Reactive Dyes by Fungal Species

2025-07-31T16:01:33+00:00

Reactive dyes are one of the most common dyes used in fabric re-dyeing; as such, their indiscriminate discharge into the environment is causing serious pollution in urban Kano, Nigeria. This research was aimed at assessing the potential of fungal species isolated from one of the major dyeing sites in Kano: Kofar Na’isa dyeing pit for the remediation of reactive dyes. The fungal species (Aspergillus striatus NEF4, Candida tetrigidarum NRRL Y-48142 1, Fusarium equiseti SPF466, and F. oxysporum FusCic45B) were isolated and identified from the dye-contaminated soil using dilution plating, pour plate, streak culture techniques, and DNA analysis. The isolated organisms were used to assess their bioremediation potential through biosorption and biodecolourisation of dye wastewater. The highest dye removal efficiency through biomass biosorption and enzymatic action was recorded after 48 hours, at pH 11.3 and a temperature of 37 °C. The dye removal by biosorption and biodecolourisation was within the ranges of 19.7 – 86.9% and 58.9 – 71.4% for A. straitus, 23.9 – 84.4% and 50.6 – 80.8% for C. tetrigidarum, 18.3 - 97.9% and 47.7 - 86.7% for F. equiseti, respectively. However, F. oxysporum displayed a negative biosorption but achieved 53.6 – 90.2% colour removal by enzymatic action. Dye removal increased with an increase in contact time due to gradual mycelial absorption. The isolated fungal species have proven to be effective in the remediation of reactive dyes, and thus, can be employed in regulating environmental contamination caused by dyes.

Enhancing Sustainability: Optimisation of Eco-Friendly Corn Starch Based Bioplastic

2025-10-15T16:48:51+00:00

Plastic is ubiquitous worldwide, and the development of bioplastics necessitates the use of biodegradable and renewable resources. This study focuses on creating and characterizing biodegradable films using varying concentrations of corn starch. The bioplastic films are plasticized with glycerol and citric acid, the latter serving as co-plasticizers in different proportions. Starch concentrations range from 5% to 20% w/v, glycerol concentrations from 5% to 25% v/v, and citric acid content from 1% to 5% w/v. The resulting bioplastics are applied to butter paper to analyse surface morphology, solubility, and water retention. The films blended with glycerol as a plasticizer consistently showed promising results. Introducing citric acid as a co-plasticizer led to a bioplastic film with reduced water retention properties. This study outlines a simple, novel, and cost-effective technique to produce bio-based plastic.

Evaluation of Heavy Metals and Histopathology in O. nioloticus and C. gariepinus of Two Selected Corridors (Almakashi and Gwani) of River Gongola in Gombe State, Nigeria

2025-10-15T16:57:56+00:00

Agricultural runoff, industrial effluents, and domestic waste are examples of anthropogenic stressors that contaminate freshwater. This is particularly applicable to Nigeria's Gongola River. This study examined the accumulation of heavy metals and histopathological alterations in Oreochromis niloticus and Clarias gariepinus from Almakashi, Gwani, and the reference site Balanga Dam. We quantified the concentrations of copper (Cu), cadmium (Cd), chromium (Cr), lead (Pb), nickel (Ni), arsenic (As), manganese (Mn), and iron (Fe) in the gills, liver, and kidneys. The gills of C. gariepinus from Almakashi exhibited the highest concentrations of Cu (17.20±1.17 µg/g), As (44.93±3.72 µg/g), and Ni (34.83±5.20 µg/g). The kidney tissues from Balanga exhibited the lowest concentrations of Fe (10.16±1.25 µg/g), Mn (1.10±0.20 µg/g), and Cu (4.23±0.30 µg/g) among O. niloticus tissues. Cadmium and lead concentrations were predominantly undetectable in kidney and liver tissues across all locations. Histopathological examination revealed that gill alterations (epithelial lifting, hyperplasia, fusion) were observed in O. niloticus from Almakashi in up to 100% of cases, while kidney necrosis was observed in C. gariepinus in up to 44.44% of cases. Steatosis (10–33.34%) and sinusoidal congestion (up to 14.29%) were among the hepatic lesions. Metal accumulation in Almakashi and Gwani was significantly greater than in Balanga Dam (p < 0.05). C. gariepinus typically exhibited elevated tissue concentrations, likely due to their consumption of benthic organisms. These findings validate that these species serve as effective bioindicators and underscore the need to rehabilitate the Gongola River and restore its ecosystems.

Effect of Soil Zinc Concentration on Plants Growth: Molecular Modelling and Docking of Interactions between Plant Proteins and Zinc Ions

2025-10-15T17:05:52+00:00

This study examines plant-soil interactions involving zinc (Zn), focusing on the physiological effects on plant development and the molecular interactions between plant proteins and metal ions. About 2 kg of soil mixed with gravel (1.5:1 v/v) were placed in pots, and seeds of sunflower (Helianthus annuus), amaranth (Amaranthus spp.), cowpea (Vigna unguiculata), and groundnut (Arachis hypogaea) were sown and irrigated for two weeks. Seedlings were treated with a 500 ppm zinc sulfate solution, and shoots, leaves, and roots were separated for length and weight measurements. Zinc concentration in digested tissues was determined using atomic absorption spectroscopy (AAS). Computational modeling and molecular docking were performed using PubChem data and structural tools such as Chimera, Phyre2, and PyMOL. The BbZIP protein structure was modeled, and active sites were predicted using COACH-D, while CAVER Web 1.0 identified quantum tunnel pathways. Phytochemical analysis revealed the presence of bioactive compounds, including flavonoids, tannins, steroids, and saponins. Treated plants exhibited reduced growth compared to the controls, with significant zinc accumulation in the soil, shoots, and roots. The highest Zn concentration (315 ppm) occurred in groundnut roots. Five major binding poses were identified, involving catalytic residues Met91, Leu92, Phe94, Ala95, Ala96, Pro210, Glu211, Ala214, Gly93, and others. Molecular docking showed a binding affinity of –3.8 kcal/mol and an inhibition constant (Ki) of 247.81 mM. The BbZIP–Zn complex was stabilized by four hydrogen bonds (Ala96, Ala290, Ser236, Leu294). Overall, this study highlights the critical role of zinc in plant stress responses and development through physiological and molecular mechanisms.

Effect of Natural Fermentation on Nutritional and Antinutritional Values of Pearl and Finger Millet

2025-10-15T17:09:00+00:00

Pearl millet (Pennisetum glaucum) and finger millet (Eleusine coracana) are common cereal crops in developing regions; however, their potential is hindered by antinutritional factors, including phytates, tannins, and oxalates, which reduce nutrient bioavailability. This study aimed to assess the impact of natural fermentation on the nutritional and antinutritional properties of these foods, thereby improving their value as dietary staples. Laboratory techniques were employed to analyze changes in proximate composition, vitamins, minerals, and antinutritional factors in fermented and unfermented samples, with the results evaluated using ANOVA (p ≤ 0.05). Natural fermentation led to substantial improvements in nutritional quality. Protein content increased from 11.50% to 13.40% in pearl millet and from 8.70% to 11.30% in finger millet. The mineral content was enhanced, with a rise in calcium levels from 332.00 mg/kg to 344.00 mg/kg in finger millet and in potassium from 240.00 mg/kg to 360.00 mg/kg in pearl millet. Natural fermentation also elevated vitamin E levels, from 0.05 mg/100 g to 0.40 mg/100 g in pearl millet and from 0.32 mg/100 g to 0.30 mg/100 g in finger millet. Antinutritional factors also decreased considerably, with phytates dropping by over 70% in both varieties, alongside marked reductions in tannins and oxalates. A slight carbohydrate reduction, which may be attributed to microbial sugar metabolism, was observed. The findings support fermentation as an accessible and effective method to enhance millet's nutritional value, providing a sustainable solution to combat malnutrition and improve food security in resource-constrained areas. This research holds significance for nutritionists, food scientists, and policymakers seeking to optimize global dietary quality.

Phytoremediation Efficiency of Arsenic from Contaminated Soil by Ricinus communis and Aloe barbadensis

2025-10-15T17:14:22+00:00

This study investigated the phytoremediation efficiency of the plants Aloe barbadensis and Ricinus communis for the removal of arsenic (As) from contaminated soil. The experiment was conducted in a Completely Randomized Block Design (CRBD) to assess arsenic (As) uptake across plant parts and residual soil after four weeks of exposure to 200, 600, and 1000 mg As treatments. Atomic Absorption Spectrophotometry (AAS) was utilized to determine Arsenic accumulation and concentration. Both plant species exhibited dose-dependent accumulation, with A. barbadensis showing significantly higher root uptake (606.51 ± 1.88 mg kg⁻¹ at 1000 mg) compared to R. communis (393.46 ± 3.09 mg kg⁻¹). Total arsenic removal efficiencies reached 89.7% for A. barbadensis and 76.5% for R. communis, confirming arsenic removal from contaminated soils. However, the uptake efficiency was found to decline slightly at higher As concentrations. Statistical analysis revealed significant differences (p < 0.001) between species, tissues, and treatment levels. The findings indicated that A. barbadensis is an excellent phytostabilizer of arsenic and recommend its use for eco-friendly remediation of As-polluted soils.

Physicochemical Parameters and Heavy Metal Oxide Concentrations in Fluorspar Deposits from Liji Hills, Yamaltu-Deba LGA, Gombe State, Nigeria

2025-10-15T18:16:53+00:00

Fluorspar mining poses significant environmental and health risks, including toxicity, as it contaminates nearby water bodies, which can lead to fluorosis, characterized by brown teeth and skeletal deformities among residents. This study analyzed two fluorspar mineral samples—Greenish brown (A) and Bluish brown (B)—collected from Liji Hills, near Gombe, to determine their metal oxide composition, crystal structure, and physicochemical properties, and to compare these values with the WHO permissible limits. Physicochemical analysis revealed that the pH of sample A decreased with time (mean = 6.91), while sample B fluctuated (mean = 6.71). Electrical conductivity decreased with time for both samples, averaging 0.25 N S cm⁻¹ for A and 0.29 N S cm⁻¹ for B. Ash content was 3.7 % for A and 2.9 % for B, while moisture content was 4.16 % and 1.0 %, respectively. X-ray fluorescence (XRF) analysis of sample A indicated major oxides in descending order: CaO = 91.5 mg L⁻¹ > SiO₂ = 3.36 mg L⁻¹ > Al₂O₃ = 0.818 mg L⁻¹ > P₂O₅ = 0.593 mg L⁻¹ > TiO₂ = 0.463 mg L⁻¹ > Fe₂O₃ = 0.418 mg L⁻¹ > MnO = 0.0246 mg L⁻¹ > K₂O = 0.0051 mg L⁻¹. Sample B showed CaO = 81.4 mg L⁻¹ > Fe₂O₃ = 6.63 mg L⁻¹ > SiO₂ = 5.65 mg L⁻¹ > TiO₂ = 0.879 mg L⁻¹ > P₂O₅ = 0.612 mg L⁻¹ > MnO = 0.0204 mg L⁻¹. X-ray diffraction (XRD) revealed that sample A had an average crystallite size of 75.87 nm with a face-centered cubic structure and Bragg angles between 25.75° and 68.77°, while sample B had a size of 13.65 nm with similar symmetry and Bragg angles from 25.94° to 56.17°. Both samples exceeded WHO limits for CaO and Fe₂O₃, indicating contamination risk. Although Pb and As were not detected, the greenish-brown sample exhibited a higher metal oxide content and greater structural quality, suggesting that Liji Hills fluorspar may contribute to environmental pollution and adverse health outcomes in nearby communities.

Eco-Friendly Solutions to Heavy Metal Pollution: The Role of Microbial Bioremediation — A Mini Review

2025-10-15T18:22:08+00:00

The accumulation of heavy metals in the environment is a grave threat and is the result of mining, agricultural, and industrial activities. This review article examines eco-friendly processes, including microbial bioremediation, to mitigate heavy metal contamination. Heavy metals have been present in the environment since the beginning of time. Their concentrations are rising due to anthropogenic factors and are contributing to several neurological, cardiovascular, and renal diseases, highlighting the urgency for effective remediation techniques. Microbial bioremediation utilizes the inherent capabilities of microorganisms to detoxify heavy metals through various processes such as bioaccumulation, biosorption, and biotransformation. These processes immobilize or convert heavy metals into less toxic forms. It offers a sustainable alternative to conventional chemical and physical remediation techniques, which are costly and often result in the production of harmful byproducts. This review discusses the complex processes involved in microbial bioremediation, the types of microorganisms used, and the relative benefits of microbial bioremediation over traditional techniques. Furthermore, biotechnological advances such as genetic engineering and the formation of microbial consortia, which improve the effectiveness of bioremediation initiatives, are also discussed. Despite the potential of microbial solutions, several issues exist that necessitate further investigation into the integration of recent advancements and modern applications to enhance the efficacy and efficiency of bioremediation methods, ultimately prioritizing environmental sustainability.

Mathematical Modelling of Zinc-Induced Inhibition on Fermentative Biohydrogen Production by Granular Sludge

2025-10-15T18:24:49+00:00

Biohydrogen production in anaerobic granular sludge reactors has led to the development of stable microbial communities that enhance substrate conversion rates. The fermentation process of sucrose by these microbial communities is a sustainable approach to hydrogen production, making biological dark fermentation an effective method for renewable biohydrogen generation. This study analyzed biohydrogen production data from granular sludge in a packed-bed upflow reactor processing sucrose-containing wastewater at 26 °C for more than 500 days, using multiple predictive kinetic models. The biohydrogen production data were converted to natural logarithms to improve linearity and reduce variance. The Morgan–Mercer–Flodin (MMF) model, coupled with the Multi-Objective Optimization by Ratio Analysis (MOORA) approach, achieved the best statistical results among nine tested predictive models based on error functions, including the highest adjusted R² value and the lowest RMSE, AICc, BIC, and HQC values. The MMF model successfully predicted all stages of hydrogen production sigmoidal growth while also modeling zinc-induced stimulation and inhibition effects. The combination of multi-criteria analysis (MOORA) with classical error-function analyses improved model discrimination, enabling a deeper understanding of microbial growth patterns under different environmental conditions to optimize biohydrogen production systems.