Studies on the effect of petroleum hydrocarbon on the microbial and physico-chemicals characteristics of soil

The microorganisms capable of degrading crude oil are present in any conceivable environment. This study was aimed at ascertaining the bacteria and fungi that are able to survive in soils contaminatedwith 3 different petroleum hydrocarbon fractions (premium motor spirit ‘PMS’, domestic purpose kerosene ‘DPK’ and automotive gas oil ‘AGO’). Soil surface samples (0.5 cm) were collected randomly from different locations in Ile-Ife in Osun State of Nigeria. Soil samples were contaminated with the hydrocarbon fractions in a ratio of 1:1 and estimated for total bacterial counts (TBC), total fungal counts(TFC), and total hydrocarbon utilizing bacterial counts (HYCUB). The following anions and cations were also determined in the soil samples; Ca2+, Mg2+, K+, Na+, NO3 +, and NO2 +. The results showed that TBC ranged from 2.1 x 103 to 3.6 x 106 cfu/g, while TFC was in the range of 0 to 2.0 x 103 cfu/g and HYCUB was in the range of 4.8 x 101 to 4.5 x 103 cfu/g. Apart from average HYCUB counts that was highest in DKP samples, other counts were highest in the PMS samples. Similar bacteria of diverse species were isolated from the contaminated soil samples, although their months of occurrences and numbersdiffered, Mg2+, K+ and Na+ all increased in all the contaminated soils, at the end of the study. In this study, the HYCUB counts were negatively correlated with Ca2+ (r = -0.667,

Studies on aerobic biodegradation activities of 2,4- dichlorophenoxyacetic acid by bacteria species isolated from petroleum polluted site

Bacteria species were screened and monitored for the efficiency of 2,4–dichlorophenoxyacetic acid (2,4-D) degradation from oil degrading laboratory stock with the view to getting the most efficient 2,4-Ddegraders, to develop an active indigenous bacterial consortium for the bioremediation of 2, 4-D polluted systems in Nigeria. The 2,4-D was utilized as sole source of carbon attaining maximum cell densities of 107 cfu ml-1 from an initial 105 cfu ml-1 in 10 days. The amount of 2,4-D utilized in a batch culture by the isolates varied significantly from an initial inoculum densities of the order of 105 cfu ml-1 and increased with increasing concentrations of 2,4-D. Growth rates ranged from 0.154 h-1 to 0.180 h-1 for SERU2 and 0.158 h-1 to 0.183 h-1 for SERU 11. Dioxygenase specific activity [ìg ml-1 chloridereleased/mg protein)-1 h-1] in actively growing cell cultures ranged from 0.010 – 0.055 (SERU 2) and 0.009-0.045 (SERU 11). The specific activity of the dioxygenase in the cell-free system ranged between 0.013 – 0.042 (SERU 2) and 0.011-0.046 (SERU 11). The pH optimum for the dioxygenase of the cell-free system was between 7.6 and 8.0 while the temperature optimum was 30oC. In conclusion the results showed that the two bacteria isolates have potential for 2,4-Dichlorophenoxyacetic acid degradation and their cell-free extracts could be used as biological alternatives in the bioremediation of 2,4-Dcontaminated system