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Environmental contamination, primarily driven by human activities such as industrialization, urbanization, and agricultural practices, has led to the accumulation of heavy metals, particularly molybdenum, in urban soils. This contamination adversely affects plant growth, food security, and poses health risks. This study explores the bioreduction potential of Bacillus cereus strain BUK_BCH_BTE1 in transforming toxic hexavalent molybdate to molybdenum blue which is a less toxic state. The bacterium was isolated from agricultural soil in Nigeria and identified through 16S rRNA sequencing. Factors influencing molybdate reduction were optimized, including carbon and nitrogen sources, molybdate, and phosphate concentrations. Glucose was found to be the most effective carbon source, while ammonium sulfate was the preferred nitrogen source. Molybdate reduction was most efficient at a concentration of 20 mM, and a phosphate concentration of approximately 3.5 mM was optimal. These findings contribute to understanding molybdate bioreduction and its potential application in addressing heavy metal pollution in the environment. Bacillus cereus strain BUK_BCH_BTE1 shows promise as an effective agent for molybdate bioreduction, with implications for mitigating environmental and health hazards associated with molybdenum contamination.

Fungal processes for the treatment of dye contaminated wastewater have the advantage of being cost-effective, environmentally friendly, and producing less sludge. This research was therefore aimed at isolating and characterizing fungus capable of decolourizing and utilizing azo dye (dimethyl yellow) as a sole carbon source using one-factor-at-a-time. Pour plating method was used to isolate the fungus on mineral salt media (MSM) following serial dilution. The isolate was then morphologically and molecularly identified as Aspergillus quadrilineatus strain BUK_BCH_BTE1 with the accession number OK178927 based on ITS1 and ITS2 rRNA gene sequence and molecular phylogenetic analysis. Characterization was conducted by studying the effect of temperature, incubation time, substrate concentration, pH, inoculum size and effect of heavy metals. The decolourization and growth of dimethyl yellow by the isolated Aspergillus quadrilineatus was optimal at substrate concentration of 200 μɡ/mL, temperature of 30 °C, 100–200 μL inoculum size, pH 5.0, and 72-h incubation time. The isolate was found to tolerate up to 4 ppm of Hg, Cu and Zn, with maximum inhibition shown by Cr and Ar. LC/MS analyses of the intermediate compounds produced during decolourization of dimethyl yellow suggested that in the fungal biodegradation of dimethyl yellow detected the formation of dimethyl yellow, 2,6-dichloro-p-benzoquinone, 1,2,3,5-tetrafluoro-4-nitrobenzene, and 3,4-dinitrobenzoic acid as metabolites. The finding from this study suggested that the isolate is a suitable candidate in bioremediation of coloured effluents particularly containing these compounds.

Palm oil mill effluent (POME) has a high concentration of organic matter and total suspended solids. However, improper disposal of oil refining wastes containing oils, fats, and sludge can cause environmental damage and harm human health due to their toxic, carcinogenic, and polluting effects. This research was carried out to solve the harmful effects caused by the release of POME to the environment. The goal of this study was to isolate a naturally occurring bacterium that could degrade POME and use it as a single carbon source. Bacteria were isolated from POME-contaminated medium using an enrichment technique. Judging by 16S rRNA partial gene sequencing, morphological, biochemical, and molecular identification methods, the isolated bacteria was identified as a novel Bacillus sp. The effects of substrate concentration, inoculum size, pH, temperature, and incubation time on the bacterial growth were investigated using a ''one factor at a time'' (OFAT) approach. The optimal conditions for the bacterium's growth were found to be pH 7.5, 35 °C, 20 % v/v substrate concentration, 6 % v/v inoculum size, and 96 hours of incubation. The isolate is capable of reducing 84 % of COD and 91 % of BOD from a POME sample. The high degradation potential of POME by the isolate suggests it can be used as a good option for bioremediation of POME-polluted areas.

Chlorpyrifos, being a frequently used organophosphate pesticide poses a significant threat to human health due to its prolonged presence in soil, plants, and water, this has raised concern. Consequently, researchers have shifted their attention towards finding methods to mitigate its toxicity or eliminate it from the environment. This has highlighted the importance of bioremediation. This study was aimed at analyzing and characterizing the metabolites of chlorpyrifos degradation by Bacillus sp. strain UPMB10 isolated from polluted environment using Gas Chromatography-Mass Spectrometry. The bacteria were successfully isolated utilizing the enrichment technique in mineral salt media, followed by screening to obtain the best isolate. Identification of the isolate was done at morphological, biochemical, and molecular levels, with a focus on the 16S rRNA gene. Phylogenetic analysis revealed the close relationship between the bacterium and Bacillus sp. strain UPMB10. Optimization (One Factor at A Time) was done to determine best growth conditions of the isolate. The optimal growth conditions obtained include, incubation time of 48 hours, a substrate concentration of 4 g/L, a pH of 7.0, a temperature of 37 °C, and an inoculum size of 2 % (v/v), these quantitative data revealed valuable insights into the factors affecting efficient degradation of pesticide. Gas Chromatography-Mass Spectrometry analysis demonstrated that the bacterium achieved a remarkable degradation efficiency of 99 % after 48 hours of incubation. Notably, Mesitylene and Dimethylmalonic acid were obtained as some of the metabolites of chlorpyrifos degradation. This result provides insight into the transformation of products generated during degradation process. The study finding revealed that Bacillus sp. strain UPMB10 exhibits a remarkable capacity for chlorpyrifos degradation, making it a promising candidate for bioremediation of insecticides and acaricides.

λ-cyhalothrin (LC), a frequently used synthetic pyrethroid insecticide, poses a substantial risk to human health and the environment due to its prolonged presence in plants, soil, and water. This study aimed to identify and characterize bacteria with the ability to degrade and utilize λ-cyhalothrin as their sole carbon and energy source. The bacteria were isolated by employing an enrichment technique on mineral salt media through a series of dilution steps. Strain isolated underwent identification through morphological, biochemical, and molecular analyses, specifically employing 16S rRNA and phylogenetic analysis, which disclosed its classification as Bacillus sp. With the accession number OR133746. Physio-cultural conditions, including temperature, initial substrate concentration, pH, incubation time and inoculum size affecting the strain's activity were investigated in MSM using a one-variable-at-a-time approach. The optimal conditions for bacterial growth and λ-cyhalothrin degradation was found to be a substrate concentration of 6 g/L, a temperature of 30 °C, a pH of 6.5, and an incubation time of 96 hours. The results of Gravimetric analysis revealed that the selected isolate exhibited notable degradation rates of 75.4 % and 100 % after 72 hours and 96 hours of incubation, respectively. These findings highlight the exceptional efficiency of the strain in degrading λ-cyhalothrin. Consequently, this strain emerges as a promising candidate for tackling pollution attributed to λ-cyhalothrin through bioremediation processes.

In the agricultural sector, a class of chemical compounds known as chlorinated phenol and phenoxyacetic acid are employed as herbicides, wood preservatives, and pesticides. Certain groups of chlorinated phenoxyacetic acid are used as herbicides for agricultural and domestic application. They are listed as priority pollutants by the United States Environmental Protection Agency (USEPA). Thus, this study focuses on bacterial isolation for 2,4-dichlorophenoxyacetic acid herbicide degradation been a toxic contaminant that hinders the quality of the soil over time, availability of certain soil microbes, non-targeted plants and poses health risk even to humans such as Hodking's lymphoma, respiratory infections e.t.c. These therefore, make it necessary to search for scientific way of dealing with this chemical from our environments. Incubation time, substrate concentration, pH, temperature, and inoculum size in mineral salt medium were all the parameters tested during the study, while 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide was used as the alternative source of carbon. Following systemic dilution of sample on mineral salt medium, three bacterial isolates (D1, D2, and D3), were isolated and subjected to lots of screening. D2 was proven to be the best. During molecular identification that involves polymerase chain reaction, gel electrophoresis, sequence alignment and phylogentic analysis, the isolated bacteria was found to be Achromobacter xylosoxidans. The bacterial isolate grew and degraded 2,4-dichlorophenoxyacetic acid herbicide at optimum conditions of 96 h incubation time, 0.72g L−1 substrate concentration, 7.5 pH, 40 °C temperature, and 400 μg/L inoculum size. High Performance Liquid Chromatography (HPLC) analysis of the residual 2,4-dichlorophenoxyacetic acid herbicide and the standard solution probe of the isolate was able to degrade up to 95.38 % of the substrate indicating great potentiality in bioremediation of herbicide polluted environments thereby, reducing if not all eliminating these toxic contaminants from our surroundings.

Herbal remedies are alternative option for the treatment, management, and prevention of different disease conditions such as malaria in most African communities due to their easy access and economic advantages. Heavy metals contaminations from the plant ingredients, processing or anthropogenic activities may render the herbal harmful for human consumption. Therefore, risk assessment of contaminating metals and antioxidant activities were determined in Agbo, a popular anti-malarial herbs mixture sold in Kano. The samples were collected from different locations across Kano State and labelled as A, B, C. The concentrations of some human cancer-causing (Cadmium Cd; Lead Pb and Chromium Cr) and some non-cancer-causing metals such as Copper Cu; Nickel, Ni in the sample were evaluated. The antioxidant properties were also evaluated using various assays, which include 2,2-diphenyl-2-picrylhydrazyl (DPPH), hydrogen peroxide (H2O2) scavenging actions, Metal Chelating, phosphomolybdate test and Reducing power properties of Agbo. Some phytochemicals (Phenolic acids, flavonoids, tannins, saponins and alkaloids) were found to be present. The values predicting the probability of human developing risk of cancer ailment after the ceaseless consumption of the herbal mixtures was found higher than a standard threshold limit (>10−4) established by USEPA. While the non-cancer predicted risk index projected the Cr, Pb and Cd (from sample B) as the leading metal pollutants of the herbal mixtures posing a risk index of more than one (>1), while Ni and Pb (from sample A and C) showed a relative safe quotient. The determined IC50 value for reducing power showed the herbal mixtures exhibiting almost same antioxidant activities with sample C having the highest (IC50 6.32 μg/mL), followed by sample B (IC50 6.36 μg/mL) and sample A (IC50 6.39 μg/mL). This suggests that excess consumption of this mixtures may be generally beneficial health-wise but unsafe due to the heavy metals which could expose the consumers to probable cancer risks and other biological process distraction.

Lead is one of the most toxic heavy metals ever known by man today, which has zero biological role. It is known to cause anemia and affect the nervous and reproductive systems with irreversible effects. Its continual usage leads to its high accumulation polluting the soil and water bodies with devastating health effects. This research, aimed at isolation and characterization of indigenous lead tolerant bacteria from contaminated soil of Anka. Results of Atomic Absorption Spectrophotometry (AAS) showed high concentration of lead (738 mg/kg) of the affected sites above the EPA standard (400 mg/kg). Similarly, a mineral salt media was used to isolate the bacteria following serial dilution. An indigenous bacterial isolate (Ac) with potential to tolerate up to 3000 mg/L Pb(NO3)2 was isolated and molecularly identified based on 16s rRNA sequencing as Bacillus cereus strain BUK_BCH_BTE2 with the accession number MT160412. The isolate was further characterized for its optimum growth and tolerance conditions using one factor at a time (OFAT). Sucrose with an optimum concentration of 5 g/L was the best carbon source for the isolate. The isolate was found to utilize ammonium sulphate as the best nitrogen source at a concentration of 2.5 g/L, with an optimum pH and tempertaure of 7.0 and 37 °C respectively. A concentration of 1000 mg/L Pb(NO3)2 was found to be the optimum concentration for the isolate. The optimum incubation time and inoculum size were found to be 48 hrs and 100 μL respectively. The fact that the isolate could tolerate high Pb(NO3)2 concentration makes it suitable for future bioremediation work involving lead.

Bioremediation process is one of the most effective methods which facilitates the cleaning of contaminated sites and restores contaminated sites through the broad biodegradative capabilities evolved by microorganisms towards undesirable organic compounds. In this study, Alcaligenes sp. with potential to degrade and utilize used engine oil as its source of carbon and energy was isolated, identified and its growth parameters optimized for efficient and better breakdown of the pollutant. Alcaligenes sp. was isolated from a used engine oil contaminated soil in an old mechanic shop, after enrichment using a carbon free (Bush-Nell Haas) media which was supplemented with used engine oil. The bacterium was identified (morphologically, biochemically, and molecularly) and studied for its ability to extract carbon from used engine oil hence degrading used engine oil. Thereafter, the various growth parameters of the bacterium isolate were optimized. Data obtained showed optimum growth parameter of 2% (v/v) used engine oil (carbon source), pH 7, temperature 37 °C, inoculum size 2 ml and incubation time 240 hours. Also, measured ribosomal RNA (16S RNA) sequence and phylogenetic analysis revealed that the isolate is a very close relative of Alcaligenes species. The degradation potential of the isolate was assessed using gravimetric analysis, and a percentage degradation of 92.5% was discovered. Overall, the results of this study suggest that Alcaligenes sp. can effectively degrade used engine oil, hence, a potential remediation organism against engine oil contamination and spills on soils or water surface.

Chromium, a transition metal element widely distributed in the earth's crust, with the valence from −2 to +6, but exists mainly in the form of trivalent and hexavalent states. Hexavalent chromium Chromium (VI) is often found in soil and ground water due to its widespread industrial use such as tannery, electroplating, and steel industries. Chromium (VI) is toxic, mutagenic, carcinogenic, and teratogenic and much more toxic to many plants, animals, and bacteria inhabiting aquatic environments because it is motile, highly toxic, soluble in water and it is a strong oxidizing agent that causes severe damage to cell membranes while the trivalent chromium Cr (III) is the most stable form of chromium and relatively immobile in the aquatic system due to its lower solubility. This study therefore, aims at identifying a bacterium that can reduce Chromium (IV) to (III) using a pour plate technique on Luria Bertani medium amended with K2Cr2O7. Graphs and tables were used for the data analysis. The effects of incubation time, pH, temperature, inoculum size, and potassium dichromate (K2Cr2O7) concentration were then examined to characterize the bacterium based on one factor at a time. To assess Chromium (VI) reduction, a spectrophotometric study of the 1, 5-diphenyl carbazide test (DPC) at 370 nm was utilized. By using molecular phylogenetic analysis and partial 16s ribosomal RNA analysis, the isolate was found to be Acinetobacter sp. strain BUK_BCH_BTE 5. The findings demonstrated that tryptic soy broth (TSB), with an optimal K2Cr2O7 level of 200 mg/L, pH of 6.5, 35 °C temperature, inoculum size of 2%, as well as incubation time of 48 h, was the most successful approach for decreasing chromium (VI). Following Nickel (Ni), the isolate was found to withstand the highest doses of Lead (Pb), Mercury (Hg), Zink (Zn), Iron (Fe), Cadmium (Cd), Arsenic (As), and Cupper, in that order. A reduced culture's (supernatant) larvacidal bioassay showed a 30% decrease in toxicity in just 48 hours, indicating that the isolate is a promising candidate, and that the reduction method is less dangerous for decontaminating chromium-contaminated environments.

Textile industry wastewater contains azo dye leftovers, which have a deleterious impact on most environmental systems. Because of safety and cost considerations, biological waste treatment is the best alternative. The goal of the study was to isolate and characterized fungus that could decolorize and use azo dye (Congo red) as a single carbon source. After serial dilution on mineral salt media, the fungus was isolated using the pour plating procedure. Based on gene sequencing of ITS1 and ITS2 ribosomal RNA region and molecular phylogenetic analysis the strain was identified as Aspergillus quadrilineatus with the accession number OK178927. Temperature, pH, substrate concentration, incubation period, inoculum size, and the influence of interacting heavy metals in Mineral Salt Medium were all investigated during the characterization process Congo red is used as the sole carbon source. This fungal isolate grew and decolorized Congo red best at 400 μɡ/ml substrate concentration, 30 °C temperature, 5.0 pH, an inoculum size of 200 μL, and a 72-h incubation time. The isolate was shown to withstand up to 6 ppm of Zink (Zn), Chromium (Cr), and Cupper (Cu), with Iron (Fe) and Arsenic (Ar) showing the most inhibition. Comparing Congo red's metabolites to a standard database of organic substances. LC/MS analyses of the intermediate compounds produced during Congo red decolorization revealed the formation of Isamine blue, p-bromo-N-(2-naphthyl)-benzenesulfonamide, 4-acetomido-N,N-dicyclohexyl-3-nitrobenzene, and azobenzene-2-sulfenyl bromide as metabolites in the fungal biodegradation of Congo red. The isolate might be a good candidate for bioremediation.

In recent years, the degradation of pollutants by microorganisms has emerged as a feasible and cost-effective strategy for restoring the quality of the environment. Anthracene is an integral part of many carcinogenic polyaromatic hydrocarbons (PAHs) and causes skin irritation. The aimed of the study is to investigate the anthracene-degrading ability bacteria and from environmental samples and characterized them using an enrichment technique. The bacterial strain was identified as Achromobacter xylosoxidans based on molecular identification achieved via 16SrRNA sequencing and phylogenetic analysis. The strain, designated as BUK_BTEG6 (accession number OM52853), was found to efficiently degrade anthracene as the sole carbon and energy source. A one factor at a time (OFAT) approach was utilized to determine the optimal growth factors that include substrate concentration, temperature, pH, and inoculum size. Results indicated that 400-600 mg/L was found as the optimal growth conditions as substrate concentration with temperature to be 35 °C, pH of 7.5 after 72 hours of incubation. Moreover, the GC-MS analysis of the culture medium confirmed the presence of degradation metabolites such as 9-10 anthraquinone, anthracene cis 1,2 dihydro diol, catechol, and cis-cis muconic acid. This isolate represents a potential candidate for use in environmental bioremediation strategies aimed at eliminating anthracene contamination from the environment.