The discharge of untreated tannery wastewater containing biotoxic substances of heavy metals in the ecosystem is one of the most important environmental and health challenges in our society. Hence, there is a growing need for the development of novel, efficient, eco-friendly, and cost-effective approach for the remediation of inorganic metals (Cr, Hg, Cd, and Pb) released into the environment and to safeguard the ecosystem. In this regard, recent advances in microbes-base heavy metal have propelled bioremediation as a prospective alternative to conventional techniques. Heavy metals are nonbiodegradable and could be toxic to microbes. Several microorganisms have evolved to develop detoxification mechanisms to counter the toxic effects of these inorganic metals. This present review offers a critical evaluation of bioremediation capacity of microorganisms, especially in the context of environmental protection. Furthermore, this article discussed the biosorption capacity with respect to the use of bacteria, fungi, biofilm, algae, genetically engineered microbes, and immobilized microbial cell for the removal of heavy metals. The use of biofilm has showed synergetic effects with many fold increase in the removal of heavy metals as sustainable environmental technology in the near future.

The tannery industry is renowned for the huge amount of toxic solid and liquid waste generated from the cleaning, fleshing, splitting, tanning, shaving and buffing of raw materials. Biomass briquettes are a proven way of generating energy from waste. This study investigates the development and characterization of biomass briquettes from tannery solid wastes (TSWs). TSWs, which comprise hair, flesh, chrome shavings and buffing dust, were collected from a tannery in Kano, Nigeria, to formulate and characterize six briquettes. Scanning electron microscopy and proximate analysis were carried out on the samples. The six briquettes, comprising varying ratios of hair, flesh, chrome shavings and buffing dust, were molded and characterized. Thermal efficiency, durability and compressive strength, among other properties, were determined for the six briquette formulations. The briquettes developed had calorific values between 18.632 and 24.101 MJ/kg. Durability of the briquettes ranged from 98.12% to 99.77%. The energy values were within the range of 17.462–24.101 MJ/kg, which was comparable to other fuel sources such as sub-bituminous coal (20.000–24.730 MJ/kg). This study shows that TSWs can be used for fuel briquette production, which is a source of sustainable energy generation. It is environmentally friendly, cost effective and affordable compared to fossil fuel.

The quest for an effective alternative means for effluent treatment is a major concern of the modern-day scientist. Fungi have been attracting a growing interest for the biological treatment of industrial wastewater. In this study, Saccharomycescerevisiae and Torulasporadelbrueckii were isolated from spoiled watermelon and inoculated into different concentrations of effluent. The inoculants were incubated for 21-days to monitor the performance of the isolates by measurement of biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrates, conductivity, phosphates, sulphates and turbidity. The results showed that Saccharomycescerevisiae had the highest percentage decrease of 98.1%, 83.0%, 60.7%, 60.5%, and 54.2% for turbidity, sulphates, BOD, phosphates and COD, respectively, of the tannery effluent. Torulasporadelbrueckii showed the highest percentage decrease of 92.9%, 90.6%, and 61.9% for sulphates, COD, and phosphates, respectively, while the syndicate showed the highest percentage reduction of 87.4% and 70.2% for nitrate and total dissolve solid (TDS), respectively. The least percentage decrease was displayed by syndicate organisms at 51.2%, 48.1% and 40.3% for BOD, COD and conductivity, respectively. The study revealed that Saccharomycescerevisiae and Torulasporadelbrueckii could be used in the biological treatment of tannery-effluent. Hence, it was concluded that the use of these organisms could contribute to minimizing the adverse environmental risks and health-hazards associated with the disposal of untreated tannery-effluents.

Background: Ocimum gratissimum (OG) is used in the traditional management of diabetes in Nigeria. This study investigated the anti-diabetic potential of OG leaf fractions (OGLF) in a rat model of Type-2 diabetes (T2D). Method: Methanol crude extract of OG leaf was fractionated with solvents of increasing order of polarity (n-hexane, chloroform, ethyl-acetate, n-butanol and water). The anti-diabetic potential of the fractions was evaluated in vivo. T2D was induced in Albino Wistar rats and treated with OGLF. Result: The T2D rats showed significant elevation in serum levels of fasting blood glucose (FBG), liver and kidney function biomarkers. At 4-weeks of intervention with OGLF, the untreated diabetic control group maintained severe hyperglycaemia in the presence of 61.7% serum insulin, 17.3% pancreatic β-cell function (HOMA-β) and 51.5% Insulin sensitivity. The glucose tolerance ability was enhanced in the n-butanol-fraction (OGb) treated group. With 74.8% available serum insulin and 38.6% improvement in insulin sensitivity, the OGb treated group had a 63.5% reduction in FBG and it was found to be most effective as it ameliorates a majority of the changes caused in the studied parameters in diabetic rats. Conclusions: The data from this study suggest that OGb fraction is a potential candidate for the development of an effective drug for the management of T2D.

Pathophysiological investigation of disease in a suitable animal model is a classical approach towards development of a credible therapeutic strategy. This study examined appropriate insulin level in selecting animal model for type 2 diabetes (T2D) studies. Albino Wistar rats (150-200g) were divided into two groups fed with commercially available normal-diet-feed (NDF) and water or fortified diet feed (FDF) (10g NDF per gram of margarine) with 20% fructose solution as drinking water. After 6 weeks of dietary regimen both groups were divided into 5 sub-groups and injected intraperitoneally with a graded dose of streptozotocin (STZ) (0, 25, 35, 45 & 55mg/kg bw.). The result showed that the FDF-fed rats increased significantly in body weight, basal serum insulin, total cholesterol, triglycerides and blood glucose levels as compared to NDF-fed rats. Ten days post STZ induction, the groups treated with STZ (45 & 55 mg/kg) developed frank hyperglycaemia with < 46.8% serum insulin, a severe deficiency typical of diabetes type 1. The NDF₂₅ and NDF₃₅ groups with 75.7% and 64.4% serum insulin respectively presented relative normoglycemia, whereas the FDF₃₅ (85.8% serum insulin) were notably hyperglycaemia (>300 mg/dL) throughout the 6weeks post diabetes confirmation. These FDF₃₅ rats were sensitive to glibenclamide, metformin and pioglitazone in lowering hyperglycaemia, hypertriglyceridemia and hypercholesterolemia The hyperglycaemia stability of the FDF₃₅ rats (85.5% insulin) together with their sensitivity to 3 different hypoglycaemic drugs strongly suggests their suitability as a non-genetic model of T2D. Hence the study shows that circulating serum insulin ≥ 85.8% with overt hyperglycaemia may be utilized as the benchmark in selecting rat models for T2D studies.