RESUMEN
The bioremediation of petroleum-contaminated soil was investigated at laboratory scale, using three different approaches. The first approach comprised biostimulation of indigenous microorganisms. The second approach involved combination of biostimulation of indigenous microorganisms and bioaugmentation by inoculation with free cells of petroleum degrading Pseudomonas aeruginosa strain Spet. The third was a variation of the second, in which inoculation with encapsulated cells in starch and sodium alginate of P. aeruginosa strain Spet was applied. The bioremediation of the original hydrocarbon-contaminated soil (3.5% dry weight) and that of diluted with clean natural soil at 1:1 w/w were investigated. By providing sufficient moisture, nutrients and aeration by stirring in the original contaminated soil, total concentration of n-alkanes was reduced by 94% after 191 days of treatment and total concentration of 16 polycyclic aromatic compounds by 79%, while for the 1:1 diluted soils biodegradation reached 89% and 79%, respectively. The results showed that bioaugmentation with free or encapsulated P. aeruginosa cells and/or soil dilution had no significant effect on biodegradation.
Asunto(s)
Biodegradación Ambiental , Restauración y Remediación Ambiental/métodos , Petróleo/metabolismo , Pseudomonas aeruginosa/metabolismo , Microbiología del Suelo , Contaminantes del Suelo/metabolismo , Secuencia de Bases , Cromatografía de Gases , Cartilla de ADNRESUMEN
A polycyclic aromatic hydrocarbon (PAH)-degrading bacterial strain Spyr1 was isolated from Greek creosote polluted soil by an enrichment method using pyrene as sole carbon and energy source. Spyr1 was identified as Mycobacterium sp. based on 16S rDNA analysis and it was capable of degrading pyrene, fluoranthene, fluorene, anthracene, and acenaphthene. The effect of entrapment in glass beads and alginate/starch mixtures on the survival and pyrene degradation ability of Spyr1 cells in liquid suspensions and soil microcosms was tested and compared with that of freely suspended cells. In general, free cells showed higher degradation of pyrene and other PAH than immobilized cells. However, immobilized cells could better tolerate PAH and they maintained their viability and PAH degradation capability for at least 1 year after storage at 4 degrees C. Entrapped cells in glass beads exhibited better pyrene biodegradation performance than alginate/starch entrapped cells in liquid suspensions and could be used effectively for at least ten repeated cycles. Alginate/starch entrapped cells exhibited better yields than glass beads entrapped cells for removing pyrene as well as mixtures of PAH in soil microcosms.