Ferdinand, Paschaline Udoka2026-03-212026-03-212019-12Ferdinand, P. U. (2019). Biodegradation of hydrocarbons by perioxidase from di-culture of Rhizopus stolonifer and Saccharomy cescerevisiae isolated from curde oil-polluted soil [Unpublished Master's Thesis]. Federal University of Technology, Owerri, Nigeriahttps://repository.futo.edu.ng/handle/20.500.14562/2429This thesis is for the award of Master of Science (M.Sc.) in Environmental Health BiologyThis study was carried out to evaluate the biodegradation of hydrocarbons by peroxidases obtained fromdi-culture of Rhizopus and Saccharomyces spp. isolated from crude oil-polluted soil. Crude oil-polluted soil samples were collected from loading jetty site at Onne. The physicochemical analysis of the soil samples revealed that it was acidic (pH 5.02) with conductivity of 723. Dissolved mineral contents of the contaminated soil included Cl, Mg, K, Ca and P03-. Heavy metals identified in the contaminated soil included Fe, As, Cu and Pb with higher values compared to the control soil. Hydrocarbon degrading peroxidase was produced from the fungal di-cultures isolated from the polluted soil using standard microbiological and biochemical techniques. Additionally, molecular identification using primers targeting the 18S RNA of extracted DNA confirmed the presence of Rhizopus stolonifer and Saccharomyces cerevisiae. Assessment of emulsification potentials of the isolated fungi showed that both organisms displayed greater potentials in drop collapse and emulsification index. Fourteen days pilot study carried out on the isolated fungi optimized for peroxidase production showed day eight (8) as the day of maximum enzyme production in the fermentation media. Optimum operational conditions for enzyme substrate reaction for peroxidase activity from the fungi were evaluated and observed at pH (4.5) and temperature (50oC) for the contaminated soil as compared to the control which was 6.0 and 40oC respectively. Peroxidase was stable in the presence of the metal ions (0.02-0.05 M concentrations) and in all the pH ranges, but Pb2+ was found to have inhibitory effect. At pH 4.5, the enzyme showed the maximum stability strength. Peroxidase retained 78% of its activity for the 180 min pre-incubation time in the presence of the metal ions, except in Pb2+ (90% loss of activity). Calcium ionshowed more stabilization strength than all other metal ions. The enzyme retained 50% of its activity for 180 min in the absence of metal ions in all the pH ranges. The analysis of kinetic parameters showed that the enzyme had KM of 1.8 mM and VMAX of 20.3 μ/mol/min against the 5mM of O-dianisidine substrate. Peroxidase incubated with the crude oil in a basal mineral medium showed strength of utilization of the carbon catenation chains in all the optimized parameters. Peroxidase from the fungal di-culture showed optimal degradative ability at acidic pH range with the peak at 5.5, with the residual oil given as 15-20% v/v. Evaluation of biodegradation by the peroxidase showed that the total weight of degraded oil was 4.02g on day 12 of 20. The weight of oil degraded increased with increase in enzyme concentration with about 80% efficiency of degradation. Increase in concentration of crude oil caused no significant difference in the weight of oil degraded. This study has shown that peroxidase has a great potential in the biodegradation of hydrocarbons present in crude oil polluted soil and is of high eco-toxicological relevance as regards to environmental remediation. However, the present work was mainly laboratory based but assessment of the effectiveness in the field would be of future benefit.enAttribution-NonCommercial-ShareAlike 4.0 InternationalBio-degradationheavy metalsperoxidaseRhizopussp.Saccharomyces sp.pHtemperaturestabilityDepartment of BiotechnologyMaster’s Thesis