Growth Behaviour of Heterotrophic Bacterial in Crude Oil Contaminated Soil under Pseudomonas sp. Amendment

Abstract

Bioaugmentation involves the introduction of exogenous microorganisms to help accelerate natural attenuation processes. It is crucial to understand the growth behaviour of total heterotrophic bacteria (THB) while carrying out bioremediation of soils polluted with petroleum hydrocarbons. Hence, the growth of THB inpetroleum hydrocarbon contaminated wet and dry soils under remediation by in Pseudomonas sp. was investigated. The wet and dry soils artificially polluted with crude oil were treated with 20-50 ml volumes of Pseudomonas sp. Total heterotrophic bacteria (THB) populations were monitored over 84 days. Growth patterns, rates and a predictive model were analyzed. Results were compared to untreated controls. From the results, THB counts increased significantly in treated soils compared to controls. The THB growth exhibited shorter lag phase and longer exponential and stationary phases. THB growth rates rose substantially in treated soils over time, while the predictive model reasonably estimated the growth of THB, but deviation increased after 70 days. Generally, bioaugmentation with Pseudomonas sp. effectively enhanced THB proliferation in hydrocarbon-polluted soil, which exhibited a rapid exponential growth within 14 days and remained stationary from 28 days and throughout. Therefore, Pseudomonas sp. is a potential bioaugmentation agent with capacity to sustain THB growth for a prolonged time required to improve biodegradation of TPH in contaminated sites.