Rhodanese is a Possible Enzyme Marker for Cyanide Environmental Stress on Aquatic Life

Rhodanese is a cyanide detoxifying enzyme. The role of man through his anthropogenic activities in and around water bodies have increased in recent times. These have led to constant exposure of water body to cyanide and cyanide compounds with increase to loss of many aquatic lives. There are limited methods employed in quick detection of cyanide in water. The aim of this paper was to present rhodanese, an enzyme, as a possible marker for detecting and monitoring water pollution as a result of environmental stress from anthropogenic activities and constant climatic changes.Keywords: Rhodanese, Aquatic Life, Water Body, Cyanide, Toxicit

Characterization of Thiosulphate: Cyanide sulphur transferase from the gut and body segments of Earthworm (Hyperiodrilus africanus)

Cyanide compounds that are by products of industrial activities are known to pose serious environmental pollution. The use of these cyanide compounds by the mining industry, along with limitations in the analysis and monitoring of these compounds, raises serious concerns regarding environmental protection and public safety. Hyperiodrilus africanus (earthworm) is directly employed within bioremediation strategies to promote biodegradation of organic contaminants and thus could be employed to rejuvenate cyanide contaminated soils. Cyanides detoxification could also prevent the risk of cyanide poisoning in poultry animals by converting cyanides in forages to a less toxic compound. This work is designed to extract and characterize rhodanese (thiosulphate: cyanide sulphur transferase, (EC 2.8.1.1) from the gut and body segments of H. africanus collected from the swampy area along Uren bank river in Ikenne community of Ogun State, Nigeria. Our results show total rhodanese activities of 1434.50 RU and 2274.28 RU and specific activities of 108.01 RUmg-1 and 83.1901 RUmg-1 in the gut and body segments of H. africanus respectively. The optimum temperature of 25 °C and optimum pH of 10.5 were obtained for both the gut and body segments enzymes. The enzyme obeyed Michaelis-Menten kinetics and the kinetic constants, Km and Vmax in the gut segment were 33.33 mM and 62.50 RU/ml for KCN substrate and 22.22 mM and 41.67 RU/ml for Na2S2O3 substrates. In the body segment, the Km and Vmax were 33.33 mM and 83.33 RU/ml; 15.38 mM and 4.00 RU/ml for the KCN and Na2S2O3 substrates respectively. Hence, we conclude that the enzyme is more specific for  Na2S2O3 than KCN as substrates, though maximum activity was observed in the body segment for KCN substrate. Ca2+, Mg2+, Ba2+, K+, Na+, Cu2+ and Zn2+ metal ion salts activated the body segment rhodanese at 1 mM and 5 mM concentrations while they have no effect on the gut segment rhodanese from earthworm. On the basis of these findings we conclude that earthworm could detoxify cyanide-containing wastes/forages and therefore promote biodegradation.Keywords: Rhodanese, earthworm, environmental protection, cyanide detoxification, bioremediatio

Partial purification and some physicochemical properties of Aspergillus flavus α-amylase isolated from decomposing cassava peels

α-Amylase is one of the most important enzymes of great significance due to its wide area of potential application in food, fermentation, textile, paper, detergent and pharmaceutical industries. This study aimed at production of α-amylase from an indigenous fungal source and also ascertaining the properties of the enzyme for maximal activity. The enzyme was isolated from decomposing cassava peels, fractionated at 70% ammonium sulphate and characterized. The fungal isolate was characterized as Aspergillus flavus. The crude enzyme extract had a specific activity of 2.40 Umg-1 which increased to 7.88 Umg-1 on fractionation with ammonium sulphate with a yield of 11.10% and purification fold of 3.28. The Km and Vmax values of 0.52±0.009 g/dL and 62.57±0.23 U/min were obtained, respectively, at 2% cassava starch substrate. The enzyme also demonstrated maximum activity at 70°C and pH 5.0. It thus produces α-amylase which is thermostable, a property which could be exploited for industrial purposes where hydrolysis of starch and other complex carbohydrates are required.Keywords: Cassava, α-amylase, starch hydrolysis, Aspergillus species, industrial application.African Journal of Biotechnology, Vol 13(52) 4657-466