Persistence and degrading activity of free and immobilised allochthonous bacteria during bioremediation of hydrocarbon-contaminated soils
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Rhodococcus sp. and Pseudomonas sp. bioremediation experiments were carried out using free and immobilized cells on natural carrier material (corncob powder) in order to evaluate the feasibility of its use in the bioremediation of hydrocarbon-contaminated soils. Terminal restriction fragment length polymorphism analysis was performed on the 16S rRNA gene as molecular fingerprinting method in order to assess the persistence of inoculated strains in the soil over time. Immobilized Pseudomonas cells degraded hydrocarbons more efficiently in the short term compared to the free ones. Immobilization seemed also to increase cell growth and stability in the soil. Free and immobilized Rhodococcus cells showed comparable degradation percentages, probably due to the peculiarity of Rhodococcus cells to aggregate into irregular clusters in the presence of hydrocarbons as sole carbon source. It is likely that the cells were not properly adsorbed on the porous matrix as a result of the small size of its pores. When Rhodococcus and Pseudomonas cells were co-immobilized on the matrix, a competition established between the two strains, that probably ended in the exclusion of Pseudomonas cells from the pores. The organic matrix might act as protective agent, but it also possibly limited cell density. Nevertheless, when the cells were properly adsorbed on the porous matrix, the immobilization became a suitable bioremediation strategy.
KeywordsBiodegradation Bioaugmentation Corncob T-RFLP analysis Pseudomonas Rhodococcus
Funding for this research was provided by Gio Eco Srl. (Segrate, Milan, Italy).
- Blackwood CB, Marsh T, Kim SH, Paul EA (2003) Terminal restriction fragment length polymorphism data analysis for quantitative comparison of microbial communities. Appl Environ Microbiol 69:926–932Google Scholar
- Boopathy R (2000) Factors limiting bioremediation technologies. Bioresource Technol 74:63–67Google Scholar
- de Carvalho CCCR, Wick LY, Heipieper HJ (2009) Cell wall adaptations of planktonic and biofilm Rhodococcus erythropolis cells to growth on C5 to C16 n-alkane hydrocarbons. Appl Microbiol Biotechnol 82:311–320Google Scholar
- Cassidy MB, Lee H, Trevors JT (1996) Environmental applications of immobilized microbial cells: A review. J Ind Microbiol Biot 16(2):79–101Google Scholar
- El Fantorussi S, Aghatos SN (2005). Is bioaugmentation a feasible strategy for pollutant removal and site remediation? Curr Opin in Microbiol 8:268–275Google Scholar
- Franzetti A, Caredda P, Ruggeri C, La Colla P, Tamburini E, Papacchini M, Bestetti G (2009) Potential applications of surface active compounds by Gordonia sp. strain BS29 in soil remediation technologies. Chemosphere 75:810–807Google Scholar
- Jimoh A (2004) Effect of immobilized materials on Saccharomyces cerevisiae. AU J Technol 8:62–68Google Scholar
- Ministero per le Politiche Agricole (1999) Decreto Ministeriale del 13/09/1999––“Metodi ufficiali di analisi chimica del suolo”Google Scholar
- Philp JC, Atlas RM (2005) Bioremediation of contaminated soils and aquifers. In: Atlas RM, Philp J (eds) Bioremediation, ASM Press, Washington,DCGoogle Scholar