Cytotoxicity study and bioremediation of petroleum contaminated soil.

Abstract

An experimental study was carried out to investigate the toxic effect of petroleum-contaminated soil by determining chromosomal aberration on mitosis of the onion root tip and demonstrating the role of mixtures or consortia of microbes in the detoxification of crude oil hydrocarbons. Soil samples were treated with different concentrations of petroleum (0, 2, 4, 8% of soil pot). All treatments with the exception of control were added 0.2 g consortium and one group was treated with only distilled water. To allow the degradation of oil components, all treatments were incubated in laboratory conditions for three periods (3,30,60 days). The results showed that chromosomal aberrations in root tip cells of Allium cepa are an abnormal anaphase with breakage, multipolar anaphase with breakage, normal metaphase and sticky metaphase, Mitotic index (MI) chromosomes that were calculated during prophase, metaphase and anaphase. The results show that adding a microbial consortium to the soil (0.2g/pot) where it recorded 600 divided cells per 1000 cells (IM=60) after incubation for 60 days, High level of crude oil 8% was caused decreasing of MI to 1.5, 3, 3.5 without any adding, while recording 35,46,50 (only distill water) in the control group. On the other hand, the high percentage removal of hydrocarbons by microbial activity with a low concentration of crude oil is 55% with increasing of time duration.