Research Article
Umema Mohsin, Madan Lowry, Ran
Abstract
Increase in demand and production of automobiles led to unexpected contamination of land around urban areas. This sudden rise in amount of petroleum hydrocarbon in soil poses great concern to environment. Natural remediation through microorganism is therefore recommended. In this study we have attempted to identify individual isolates at local petroleum contaminated sites and prepare consortia to enhance degree of bioremediation. Soil sample collected from three sites which further investigated for microbial soil respiration and enumerated for THBC and PDBC growth rate. Distinct colonies were investigated for identification through 16s RNA and protein profiling, followed by preparation of unique consortium by mixing isolated bacteria. Degradation of petroleum hydrocarbons were estimated by recording growth rate of individual isolates and consortium. The amount of CO2 evolved in test samples, i.e., T1, T2 and T3 following addition of 20 mg/kg and 40 mg/kg of Na2CO3 indicated decline by 50% throughout the period of examination when compared to control. Growth of THBC in test samples were significantly higher than control (P<0.05). For PDBC the total viable counts were 3.17 × 106 CFU/g, 3.03 × 106 CFU/g and 3.10 × 106 CFU/g in samples T1, T2 and T3, respectively. Identification of isolates by 16s rRNA sequencing revealed that I1 was Pseudomonas rhodesiae, I2 was Caulobacter henricii, I3 was Cupriavidus gilardii and I4 was Phenylobacterium koreense. Individually Pseudomonas rhodesiae performed better than other isolates, however, among all five consortia, best result was recorded for consortium D which showed exceptional growth from 3rd day onward. In conclusion our results evidently showed that consortium D significantly survived in petroleum contaminated soil samples. Sustained growth rate of bacteria is predictive of its effectiveness in breaking down complex PHCs in more usable intermediates.