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Phenanthrene Degradation in Soils Co‐Inoculated with Phenanthrene‐Degrading and Biosurfactant‐Producing Bacteria
Author(s) -
Dean Stacy M.,
Jin Yan,
Cha Daniel K.,
Wilson Sviatlana V.,
Radosevich Mark
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.3041126x
Subject(s) - phenanthrene , biodegradation , rhamnolipid , chemistry , mineralization (soil science) , bioavailability , bacteria , sorption , environmental chemistry , bioremediation , bioaugmentation , microbiology and biotechnology , loam , pseudomonas , pseudomonas putida , food science , soil water , organic chemistry , pseudomonas aeruginosa , biology , ecology , adsorption , bioinformatics , nitrogen , genetics , enzyme
Contaminant sorption within the soil matrix frequently limits biodegradation. However, contaminant bioavailability can be species‐specific. This study investigated bioavailability of phenanthrene (PHE) to two PHE‐degrading bacteria ( Pseudomonas strain R and isolate P5‐2) in the presence of rhamnolipid biosurfactant and/or a biosurfactant‐producing bacterium, Pseudomonas aeruginosa ATCC 9027. Pseudomonas strain R mineralized more soil‐sorbed PHE than strain P5‐2, but in aqueous cultures the rate and extent of PHE mineralization by P5‐2 exceeded that by P strain R. In Fallsington sandy loam (fine‐loamy, mixed, active, mesic Typic Endoaquult) (high PHE‐sorption capacity) the addition of rhamnolipid increased PHE mineralization by P strain R. Phenanthrene mineralization in soils inoculated with P5‐2 was minimal and no enhancement in PHE degradation was observed when biosurfactant was added. Co‐inoculation of Fallsington sandy loam with the biosurfactant producer did not affect PHE mineralization by isolate P5‐2, but significantly enhanced PHE mineralization by P strain R. The enhancement of PHE mineralization could not be explained by P. aeruginosa –mediated PHE degradation. The addition of rhamnolipid at concentrations above the critical micelle concentration (CMC) resulted in enhanced PHE release from test soils. These results suggest that the PHE‐degrading strains were able to access different pools of PHE and that the biosurfactant‐enhanced release of PHE from soils did not result in enhanced biodegradation. The results also demonstrated that bacteria with the catabolic potential to degrade sorbed hydrophobic contaminants could interact commensally with surfactant‐producing strains by an unknown mechanism to hasten the biodegradation of aromatic hydrocarbons. Thus, understanding interactions among microbes may provide opportunities to further enhance biodegradation of soil‐bound organic contaminants.