Preliminary Investigation into the Ability of Tropical Rhizobia to Degrade Petroleum Products as Environmental Pollutants and Chemical Bases for Some Syhnthetic Pesticides

This study involves the investigation of the ability of some Tropical Cowpea Rhizobia to degrade crude oil in oil spilled soil as well as crude oil products which includes diesel, kerosene and petrol. This was carried out by introducing the rhizobial strains Rhizobium species CWP A17, R. species CWP G34A, R. species CWP G34B, R. species C, Bradyrhizobium species R. 3IB, Br. species FA3, Br. species T5BL 442 , Br. speciesUSAD 4675 (400) and Br. species 1495 MAR into various fuel media. The population and absorbance of the various bacteria were taken in each case at 24 hours interval for 10 days. Each of the various Rhizobia and Bradyrhizobia degraded hydrocarbon. The physicochemical parameters of the oil polluted soil were determined alongside with those of the control. The particle size analysis of the polluted soil sample indicated that on the average the soil is made up of 10.69% sand, 84.86% silt and 4.5% clay. This corresponds to silt loam soil. Other parameters indicated the utilization of the various hydrocarbon contents by the plant. The effects of oil polluted soil on nodulating and nitrogen fixing abilities of the tropical rhzobia were examined by inoculating each of the bacterial strain on the cowpea (Vignaunguiculata) grown on the oil polluted soil in a green house. These were observed at two weeks interval for 12 weeks. The various plant indices (i.e. height, number of leaves, and leaf area) showed retarded germination of the plant of oil polluted soil when compared to the control. However, there was slight difference in the case of stem girth. The stem girth of the plants grown on oil populated soil is wider. The biodegradation experiment showed that for the various rhizobia grown in crude oil, diesel, petrol and kerosene media, the degradation of the hydrocarbon occurred, in which the organisms were able to utilize the fuels as carbon source.