Efficiency Testing of Some Local Bacterial Isolates on Biodegradation for Gas Oil in Contaminated Soil Extract

Abstract

A factorial experiment was carried out in glass containers using a randomized complete design (RCD) in clay soil mixture to study the test of pollination ability with four types of Rhizobium isolates isolated from the root nodes of four plants of the leguminous family. (Vigna anguiculata L (R1), Vicia faba (R2), Phaseolus (R3), Vigna radiate (R4) and a mixture of (B. megaterium, B.pumilus, B.lichenitormis, B.amylolilguefaciens) (B) on the consumption of gas oil at three levels (0, 2, 4%) by measuring the amount of CO2 released, the percentage and quantity of gas oil consumption and the concentration of the bio-emulsion produced by these isolates in industrial agricultural media. The results showed that all types of bacterial isolates led to a significant increase in the amount of CO2 released for the two levels (2%, 4%) compared to the level (0%), the treatment of adding Rhizobia bacteria isolated from the mung bean plant was recorded (R4) Vigna radiate and at the level (4%) the highest liberated amount, it reached to (390.40) mg of 100 gm-1 of soil compared to the comparison and at the level (0%) that was (126.15)) mg of 100 gm-1 of soil, resulted in a significant decrease in the residual amount of gas oil in the soil and for all levels of gas oil, and the treatment of adding Bacillus mixture recorded the lowest residual amount, it reached to (0.45) ml 100 gm-1 soil out of (2) ml added compared to the control treatment which recorded (1.75) ml 100 gm-1 soil at the level (2%). The treatment of adding a mixture of Bacillus (B) bacteria recorded the highest degraded percentage at the 2% level, which amounted to (77.5%) compared to the control treatment which recorded (12.5%), whereas, the treatment of adding Rhizobia isolated from Vigna radiate (R4) recorded the highest degraded percentage at the 4% level, which amounted to (68.75%) compared to the control treatment (23.75%). All bacterial isolates recorded the highest concentration of the bio-emulsion at the level (0%) and the lowest concentration at the level (4%), and the Bacillus bacteria mixture (B) recorded at the level (0%) the highest concentration of the bio-emulsion was (27.75) mg L-1.