Potential of immobilized microbial consortium in petroleum contaminated soil rhizodegradation.pdf

1、The present study focused on the evaluation of thizosphere bioaugmentation of S. cannabina with oil degraders culture in immobilized and free form. The main outcome of this research includes:
　　 Soil texture effect a

2、mendment was indispensible as it was found in the beginning clayey textured soil did not support the thizodegradation significantly due to insufficient plant growth and soil compactness and hardness interfere in deep roo

3、t penetration (chapter 2).
　　 Bioaugmentation with free as well as immobilized bacterial form did not enhanced plant growth as it is not being essential that inoculum used must also act as plant growth promoting bact

4、eria. Overall, growth performance indicators suggested that S. cannabina is an ideal candidate for thizoremediation application based on highest potential for root depth penetration, biomass production, root tips number,

5、 root surface area, relative growth rate (root biomass) and root to shoot ratio and were able to germinate from seed and tolerate the presence of crude oil contamination at the exposed soil sample concentrations (chapter

6、 3).
　　 Root exudates enhance the cometabolic processes and increase the microbial number and their activity. Indigenous microbial community has adopted the adverse environment afier long exposure of TPH pollutants.

7、The potential microbial community belongs to Flavobacteriaceae, Pseudomonadaceae, Rhizobiaceae, Halomonadaceae, Rhodospirillaceae, Erythrobacteraceae families and Cyanobacteria Presence of Sesbania plant was a key factor

8、 of banding pattern in the DGGE profile, neither bioaugmentation by free culture nor immobilized oil degrading culture. However, band 17 which belongs to Flavobacteriaceae was only found in CR and CN, these unidentified

9、bacteria might be the most active TPH degraders due to its higher abundance in these samples with subsequent higher TPH degradation (chapter 4) This interpreted that the less diverse and more relative abundant hydrocarbo

10、n degraders species were under the influence of the S. cannabina which was found sufficient to degrade recalcitrant fraction of TPH and no further bioaugmentation was seems to be effective. Moreover, plant thizosphere im

11、mobilized bacterial community in its surrounding therefore immobilized culture has no obvious effect on petroleum degradation. The control without bioaugmentation was found most efficient in thizoremediation outcomes. Ev

12、idence in the current work supports microbial-assistated remediation was the major TPH removal pathway from soil, enhanced by the presence of S. cannabina (the thizosphere effect). Bioaugmentation and biostimulation alon

13、e appeared to be effective in enhancing intrinsic biodegradation of oil hydrocarbons in soil, however with plant this technique was ineffective due to the presence of root exudates which select bacterial species and thei

14、r subsequent activity itself. Rhizosphere bioaugmentation was ineffective and natural plant-microbe interaction was responsible for high TPH degradation directly and indirectly by promoting plant growth. Heterotrophic lo

15、ad showed that immobilized microbial consortium was not stable enough to survive for long time. One important reason for effectiveness of bioaugmentation was that the inoculated culture was isolated from the freshly cont

16、aminated site while the soil sample was composted and weathered having more recalcitrant fraction so th e stage of degradation was different which required different microbial community with relevant substrate utilizing