Bioremediation

Flux chambers measuring methyl bromide emission during field fumigation. Photo credit: Laurence G. Miller, USGS

Shaun Baesman applying a suspension containing cells of Aminobacter ciceronei strain IMB-1 to the soil surface prior to fumigation. Photo credit: Laurence G. Miller, USGS

Methyl bromide is a natural and man-made halocarbon which contributes to stratospheric ozone depletion. We discovered that natural populations of bacteria in soils play a major role in mitigating the flux of methyl bromide added during pre-plant fumigation for crops such as strawberries. Methylotrophic bacteria capable of degrading a variety of C1 compounds including methyl halides were isolated from a strawberry field in Irvine, CA. We were able to purify and grow these bacteria (Aminobacter ciceronei strain IMB-1) to high density in aerobic culture for the purpose of adding them back to soils to prevent methyl bromide efflux. We obtained U.S. patent # 6,013,254 titled “Method for Enhancing Oxidation of Methyl Bromide with Strain IMB-1 (ATCC 202197) During Agricultural Fumigations” for this process. Principal investigators were Tracy Connell, Larry Miller, and Ron Oremland. Janet Guidetti, Kelly Goodwin, Caleb Sasson, Jeffra Schaefer, Rosie Hudleston, and Shaun Baseman contributed to this study. For further information: Microbial Biogeochemistry of Aquatic Environments 

See also:

Oremland, R.S., Miller, LG., Culbertson, C.W., Connell, T.L., and Jahnke, L.L. 1994. Degradation of methyl bromide by methanotrophic bacteria in cell suspensions and soils. Appl. and Environm. Microbiol., vol. 60, 3640-3646.

Miller, L.G., Connell, T.L., Guidetti, J.R., and Oremland, R.S. 1997. Bacterial oxidation of methyl bromide in fumigated agricultural soils. Appl. and Environm. Microbiol., vol. 63, 4346-4354.

Connell Hancock, T.L., Costello, A.M., Lidstrom, M.E., and Oremland, R.S. 1998. Strain IMB-1, a novel bacterium for the removal of methyl bromide in fumigated agricultural soils. Appl. and Environm. Microbiol., vol. 64, 2899-2905.

Schaefer, J.K., and Oremland, R.S., 1999, Oxidation of methyl halides by the facultative methylotroph, strain IMB-1: Appl. Environ. Microbiol., v. 65, p. 5035-5041. (on-line abstract)

and the following review articles:

Oremland, R.S., 2003, Biodegradation of atmospheric halocarbons, in Haggblom, M.M., and Bossert, I.D., eds., Dehalogenation: Microbial Processes and Environmental Applications: Dordrecht, Kluwer Academic Publishers, p. 323-345.

Schäfer, H., Miller, L.G., Oremland, R.S., and Murrell, J.C., 2007, Bacterial cycling of methyl halides: Advances in Applied Microbiology, v. 61, p. 307-346.

For more information contact Laurence G. Miller, Shaun M. Baesman , and Ronald S. Oremland, Menlo Park Regional Office.

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USGS bench-scale fermenter produces 8 liters of cells (10ˆ12 cells/ml) of A. ciceronei strain IMB-1 in 3 days. Photo credit: Laurence G. Miller, USGS

We demonstrated that methylotrophic bacteria (Aminobacter ciceronei strain IMB-1) could be employed to remove methyl bromide from large volumes of contaminated air that resulted from contained fumigations (e.g. quarantine fumigations of shipping containers, or structural fumigations of buildings for pests). We designed bioreactors that could rapidly remove fumigation levels (up to 30,000 ppm) of methyl bromide from the waste stream of contained fumigations. Currently, these wastes are vented to the atmosphere contributing to the destruction of ozone in the stratosphere. We showed that a bioreactor containing 10,000 liters of cells in growth phase (conveniently sized to fit on the back of a truck) could remove all of the methyl bromide from a fumigated shipping container in less than 5 hours. A larger bioreactor could be fed by hoses serving several containers at a time, for instance at a large receiving port or harbor. These results led to a patent using IMB-1 to degrade methyl bromide (Patent No. 6,916,446 entitled “Bioreactor Method, Apparatus and Product Thereby” by Laurence G. Miller, Shaun M. Baesman, and Ronald S. Oremland). See the following for more information: Microbial Biogeochemistry of Aquatic Environments

Reference:

Miller, L.G., Baesman, S.M., and Oremland, R.S., 2003, Bioreactors for removing methyl bromide following contained fumigations: Environmental Science and Technology, v. 37, no. 8, p. 1698-1704. (on-line abstract or on-line pdf file)

For more information contact Laurence G. Miller, Shaun M. Baesman , and Ronald S. Oremland, Menlo Park Regional Office.

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