Bioefficiency of Clarias gariepinus Liver Rhodanese and Physicochemical Parameters of Soil from Cassava Effluent Contaminated Odo-Oba River, Ogbomosho, Oyo State, Nigeria
Cyanide contamination of Soil and aquatic environment has become a great concern in Nigeria because of increase in the number of cassava processing milling plants. The sample collection and the conduct of this experiment took place between September and October when the country is experiencing late rainfall. The levels of physicochemical parameters in soil and plant samples were obtained using Atomic Absorption Spectrophotometer. Soil and plant samples of Amaranthus spinosus were obtained from cassava processing site (site X) and other samples 100m to the cassava mills (site Y) as control. The concentration of metals in soil samples in mg/kg at site ‘X’ recorded were Cr(39.0mg/kg), Mn(3.5mg/kg), Cu(33.0mg/kg), Fe(4.3mg/kg), Pb(2.5mg/kg), and Zn(52.5mg/kg) while that of site ‘Y’ were Cr(16.5mg/kg), Mn(1.3mg/kg), Cu(13.0mg/kg), Fe(1.9mg/kg), Pb(0.3mg/kg), and Zn(17.0mg/kg). The concentration values for AS, Cd and Nickel in the environment were below detection limit for all soil and plant samples. The concentrations of metals in A. spinosus root and shoot in mg/kg from sites ‘X’ were Cr(6.00mg/kg - 8.50mg/kg), Fe(0.55mg/kg - 0.80mg/kg), Cu(4.00mg/kg - 5.50mg/kg), Pb(0.05mg/kg - 0.08mg/kg), Zn(6.00mg/kg - 8.00mg/kg), Mn(0.35mg/kg - 0.5mg/kg) while that of site ‘Y’ were Cr(5.50mg/kg - 8.00mg/kg), Fe(0.545mg/kg - 1.00mg/kg), Cu(4.00mg/kg - 6.50mg/kg), Pb(0.03mg/kg - 0.08mg/kg), Zn(7.50mg/kg - 9.50mg/kg), Mn(0.30mg/kg - 0.60mg/kg). The values of some metals analyzed were above the recommended values by WHO and FEPA. The analysis of effluents and surface water samples resulted in higher figures for most of the parameters and acidic pH in cassava effluent than the surface water sample. The mode of phytoremediation was also investigated. Data obtained suggested the plants could be used for phyto-extraction of these metals. Rhodanese, enzyme that detoxify cyanide was extracted and characterized from the liver of Clarias gariepinus of cassava effluents contaminated Odo-Oba River. The results show specific activities of 0.0526RUmg-1. The optimal temperature and pH of 30˚C and 7.0 were recorded for the enzyme respectively. The Vmax of 9.62RU/Ml and 6.33RU/Ml were obtained for the KCN and Na2S2O3 substrates while for the Km, higher figures of 49.4mM and 28.5mM were recorded respectively. However, the Km values of the fish liver Rhodanese of Clarias gariepinus indicated higher affinity for thiosulphate (Na2S2O3) than for potassium cyanide (KCN) as a substrate, although maximum activity was observed for KCN substrate. Inhibition studies on the enzyme with a number of chloride salts showed that the activity of the enzyme was not affected by Mg2+,, Mn2+,Ca2+ while Ba2+,Hg2+ and Cu2+ inhibited the enzyme considerably.