Grantee Research Project Results
1999 Progress Report: The Effect of In Situ Biosurfactant Production on Hydrocarbon Biodegradation
EPA Grant Number: R826161Title: The Effect of In Situ Biosurfactant Production on Hydrocarbon Biodegradation
Investigators: Strevett, Keith A. , Sabatini, David A. , Tanner, R. , Knox, Robert
Current Investigators: Strevett, Keith A. , Sabatini, David A. , Everett, Jess , Tanner, R.
Institution: University of Oklahoma
EPA Project Officer: Aja, Hayley
Project Period: March 10, 1998 through March 9, 2001 (Extended to September 9, 2001)
Project Period Covered by this Report: March 10, 1999 through March 9, 2000
Project Amount: $323,072
RFA: Exploratory Research - Environmental Engineering (1997) RFA Text | Recipients Lists
Research Category: Land and Waste Management , Safer Chemicals
Objective:
The goal of this project is to investigate the effect of biosurfactants on the bioremediation of chemical matrices, specifically: (1) the impact (or enhancement) of biosurfactants on the bioavailability of hydrocarbons; (2) assessment of microbial membrane characteristics as altered by biosurfactants that may have an impact on the bioavailability of hydrocarbons; and (3) impact of biosurfactants on microbial migration (the ability of a microorganism to transport with a contaminated plume).Progress Summary:
Abiotic with Biosurfactant (Abiotic System?No Granular Media)
- Singly: Individual solubility of the four model compounds in water is determined in this set of experiments. The purpose of this set of experiments was to determine a baseline value for comparison with other experiments where soil and biosurfactant are present.
- NAPL: The purpose of this set was to determine the solubility of the model compounds when present as part of a NAPL. The data obtained from this set of experiments serve as a baseline for NAPL in soil and ex situ biosurfactant addition.
- Ex situ biosurfactant addition: The purpose of this experiment was to determine the solubility of the model compounds in the presence of ex situ addition of biosurfactant. Results for this set of experiments will serve as a baseline for bioavailability for abiotic and biotic experiments in the presence of soil. As completed for rhamnolipid, little enhancement in solubility was observed. Three different concentrations for the biosurfactant addition (0.25, 1.0, and 10 times the critical micelle concentration [CMC]) were examined. Toluene showed the maximum enhancement at 10 times CMC. TCE and o-DCB did not show any solubility enhancement for all of the biosurfactant concentration examined. A control experiment with sodium dodecyl benzyl-sulfonate n(SDBS) also showed no enhancement in solubility at 0.25 and 1.0 times CMC. However, as expected, a 50-percent increase in o-DCB was observed for 10 times CMC of SDBS.
Biotic with Soil
The organism used for the anaerobic portion of the project is Bacillus (B.) licheniformis strain JF-2 (McInerney, et al., 1990). A reliable protocol for collecting and purifying the produced biosurfactant was previously developed. In addition, a mutant strain of B. licheniformis JF-2, which has lost the ability to produce any biosurfactant, is available as a control. Soils used in the following experiments are from two locations: a gas condensate contamination site located in Ft. Lupton, Colorado; and a crude oil spill in northeastern Oklahoma. The Colorado location was previously studied and found to contain high numbers of hydrocarbon degraders in the contaminated zone (Gieg, et al., 1999). Both contaminated and uncontaminated soils were collected from both sites. The following components were added to serum bottles to analyze toluene degradation: Ft. Lupton contaminated soils, media, toluene (approximately 1,997.4 µmol/L headspace, time zero), and purified biosurfactant in various concentrations ranging from zero to 10 times the CMC (Tables 1 and 2). With the exception of one control set that contained sterilized soil, all soils were unsterilized. One series of experiments was performed under methanogenic conditions, and another was performed under sulfate-reducing conditions (Tables 1 and 2). Toluene levels are measured by headspace gas chromatography (GC), as are methane levels for the methanogenic series. For the sulfate-reducing series, 1-mL samples of media have been collected under anaerobic conditions for analysis of sulfate levels at the conclusion of the experiment.
Table 1. Changes in toluene and methane levels under methanogenic conditions.
Amount of Biosurfactant |
Change in Toluene |
Change in Methane |
(µmol/L headspace) |
(µmol/L headspace) | |
0 (sterile soils) |
-87.71 |
+ 1 |
0 (live soils) |
-171.87 |
+ 135 |
1/4 CMC |
-899.25 |
+ 128 |
CMC |
-303.51 |
+ 374 |
10 CMC |
-445.45 |
+ 561 |
Table 2. Changes in toluene under sulfate-reducing conditions.
Amount of Biosurfactant |
Change in Toluene (µmol/L headspace) |
0 (sterile soils) |
-94.83 |
0 (live soils) |
-43.64 |
1/4 CMC |
8.66 |
CMC |
-84.52 |
10 CMC |
-446.19 |
Future Activities:
Future activities include developing a procedure for mass production of rhamnolipid using chemostat; testing for surfactant-producing bacteria in contaminated Fort Lupton, Colorado, soil; and conducting experiments on rhamnolipid and lipoprotein biosurfactants, naphthalene, toluene, and hexadecane.Journal Articles:
No journal articles submitted with this report: View all 3 publications for this projectSupplemental Keywords:
applied biosurfactant technology, microbial surface thermodynamics, biodegradation kinetics, environment restoration, toluene, naphthalene, hexadecane, JP-4, rhamnolipid, lipopeptide., Scientific Discipline, Toxics, Waste, Ecosystem Protection/Environmental Exposure & Risk, Bioavailability, Bioremediation, Ecology and Ecosystems, 33/50, Environmental Engineering, aerobic degradation, bioremediation model, Toluene, biodegradation, chemical transport, biokinetic model, contaminant release, biosurfactant specifity, surface thermodynamicsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.