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Sowers@umbi.umd.edu Lab Homepage: http://www.umbi.umd.edu/~sowers/home.html |
Biology of Methanogenesis and Anaerobic Bioremediation
Regulatory pathways in the methanogenic Archaea with emphasis on catabolic gene expression; mechanisms of anaerobic reductive dechlorination in sediments impacted by PCBs and other organochlorines; bioprocess scale-up of microorganisms from extreme environments.
Research
interests
Regulatory pathways in the methanogenic
Archaea
The Archaea, Bacteria and Eucarya represent the three primary phylogenetic lineages that diverged and evolved from a common progenote. The controlled expression of gene products involved in methanogenesis is essential for complete biomass conversion and bioremediation in anaerobic sediments, however, the mechanisms of catabolic gene regulation in the third lineage, the Archaea, is not yet known. The goal of this project is use genetic approaches combined with genomics and proteomics to determine whether gene expression in the Archaea functions by mechanisms that are analogous to the other two lineages, Bacteria and Eucarya, or by mechanisms that are unique to this phylogenetic line. Regardless of which mechanism(s) is revealed by this investigation, the results will provide further insight into the global molecular strategies of gene regulation. This research is divided into three projects: 1) mechanisms of gene transcription; 2) global regulatory pathways for methanogenesis; 3) bioprocess scale-up of archaeal proteins. For more details, go to the Sowers' Lab Homepage.
Microbial
Reductive Dechlorination of Organochlorines
Coastal anaerobic sediments are the ultimate global sinks for accumulation of chlorinated hydrocarbons such as polychlorinated biphenyls (PCBs) where reductive dehalogenation may have a significant role in their biotransformation. Understanding this microbial process is critical for making management decisions concerning both remediation and risk assessment of PCB-impacted coastal regions. Our lab and collaborators have for the first time identified two PCB dechlorinating microbes and based on this discovery developed molecular ribosomal probe assays, which are currently being optimized for detection of PCB dechlorinating catalysts in selected coastal sediments. Results of these studies will provide fundamental information on the biocatalytic processes required to develop bioremediation strategies and promote intrinsic PCB transformation in impacted marine harbor sediments and dredge deposition sites. In addition to the bioremediation implications, the investigations proposed here will expand our understanding of the organismal and metabolic biocomplexity that is potentially available for dehalogenation processes in coastal sediments. This research is divided into three projects: 1) gene probe assessment of PCB dechlorinating potential; 2) proteomics and biochemistry of microbial dehalogenation; 3) ecology of the global chlorine cycle. For more detatils, go to the Sowers' Lab Homepage.
Recent
publications
Anderson, K.L., E.E. Apolinario, S.R. MacAuley, and K.R. Sowers. 2009. Localization of a regulatory region within the 5’ untranslated leader region of an archaeal CO dehydrogenase/acetyl-coenzyme synthase. J. Bacteriol. Accepted (e-published ahead of print on 18 September 2009) [ABSTRACT].
Allen, M.A., F.M. Lauro, T.J. Williams, D. Burg, K.S. Siddiqui, D. De Francisci, K.W.Y. Chong, O. Pilak, H.H. Chew, M.Z. De Maere, L. Ting, M. Katrib, C. Ng, K.R. Sowers, M.Y. Galperin, I.J. Anderson, N. Ivanova, E. Dalin, M. Martinez, A. Lapidus, L. Hauser, M. Land, T. Thomas, and R. Cavicchioli. 2009. The genome sequence of the psychrophilic archaeon, Methanococcoides burtonii: the role of genome evolution in cold adaptation. ISME J. 3: 1012-1035 [ABSTRACT].
Kjellerup, B.V., Kjeldsen, K., Lopes, F., Abilggaard, L., Ingvorsen, K., Frølund, B., Sowers, K.R. and Nielsen, P.H. 2009. Biocorrosion and biofilm formation in a nutrient limited heating system subjected to alternating microaerophilic conditions. Biofouling. 25(8): 727-737.
MacAuley, S.R., S.A. Zimmerman, E.E. Apolinario, C. Evilia, Y.-M. Hou, J.G. Ferry, K.R. Sowers. 2009. The Archetype g-Class Carbonic Anhydrase (Cam) Contains Iron when Synthesized in vivo in Methanosarcina acetivorans. Biochemistry 48(5): 817-9 [ABSTRACT].
Tal, Y., H.J. Schreier, K.R. Sowers, J.D. Stubblefield, A.R. Place, and Y. Zohar. 2009. Environmentally Sustainable, Fully Contained Marine Aquaculture. Aquaculture 286: 28-35. [ABSTRACT].
Sowers, K.R. 2009. Methanogenesis. In: Schaechter, Lederberg, Alexander, Haselkorn, Ingraham, Baross, Schmidt, Laskin, Hopwood, Summers, Baulcombe, Levin, White, Fierer, Baldauf (eds.), Encylopedia of Microbiology, 3rd edition. Elsevier, Inc. ISBN: 978-0-12-373944-5.
Kjellerup, B., Olesen, B.H., Sowers, K. R., Nielsen, P., Nielsen, J. 2008. In situ detection of bacteria involved in cathodic depolarization and stainless steel surface corrosion using microautoradiography. J. Appl. Microbiol. 105: 2231–2238. [ABSTRACT].
May, H.D., G. S. Miller, B.V. Kjellerup, K.R. Sowers. 2008. Dehalorespiration with Polychlorinated Biphenyls by an Anaerobic Ultramicrobacterium. Appl. Environ. Microbiol. 74: 2089-2094. [ABSTRACT].
Kjellerup, B.V., X. Sun, U. Ghosh, H.D. May and K.R. Sowers. 2008. Site specific microbial communities in three PCB-impacted sediments are associated with different in situ dechlorinating activities. Environ. Microbiol. 10: 1296-1309 [ABSTRACT].
Fagervold, S.K., H.D. May and K.R. Sowers. 2007. Microbial reductive dechlorination of Aroclor 1260 in Baltimore Harbor sediment microcosms is catalyzed by three phylotypes within the Chloroflexi. Appl. Environ. Microbiol. 73: 3009-3018 [ABSTRACT].
Sowers, K.R., S. DasSarma and P. Blum. 2007. Gene transfer in Archaea. In: C. A. Reddy, T. J. Beveridge, J. A. Breznak, G. A. Marzluf, and T. M. Schmidt (ed.), Methods for General and Molecular Microbiology. American Society for Microbiology, Washington, D. C. ISBN: 978-1-55581-223-2.
Sowers, K.R. and K. Anderson. 2007. Molecular Genetics of Archaea. In: R. Cavicchioli (ed.), Archaea: Molecular Cell Biology. American Society for Microbiology, Washington, D. C., pp. 463-477. ISBN: 978-1-55581-391-8.
D.L. Maeder, I. Anderson, T. Brettin, D. Bruce, P. Gilna, C. S. Han, A. Lapidus, W.W. Metcalf, E. Saunders, R. Tapia, and K.R. Sowers. 2006. The Methanosarcina barkeri genome: comparative analysis with Methanosarcina acetivorans and Methanosarcina mazei reveals extensive rearrangement within methanosarcinal genomes. J. Bacteriol. 188: 7922-793 [ABSTRACT].
H.D. May, L.A. Cutter, G.S. Miller, C.E. Milliken, J.E.M. Watts, and K.R. Sowers. 2006. Stimulatory and Inhibitory Effects of Organohalides on the Dehalogenating Activities of PCB-Dechlorinating Bacterium o-17. Environ. Sci Technol. 40: 5704 -5709 [ABSTRACT].
Reid, I.N., W.B. Sparks, S. Lubow, M. McGrath, M. Livio, J. Valenti, K.R. Sowers, H.D. Shukla, S. MacAuley, T. Miller, R. Suvanasuthi, R. Belas, A. Colman, F.T. Robb, P. DasSarma, J.A. Muller, J.A. Coker, R. Cavicchioli, F. Chen, S. DasSarma. 2006. Terrestrial models for extraterrestrial life: methanogens and halophiles at Martian temperatures. Int. J. Astrobiol. 5: 89-97. [ABSTRACT]
Kjellerup, B.V., G. Gudmonsson, K.R. Sowers, P.H. Nielsen. 2006. Evaluation of Analytical Methods for Analyzing the Distribution of Biofilm and Active Bacteria in a Commercial Heating System. Biofouling 22: 145-151 [ABSTRACT].
Sowers, K.R. and J.E.M. Watts. 2006. The study of strictly anaerobic microorganisms. In: F. A. Rainey and A. Oren (ed.), Methods in Microbiology - Extremophiles, v. 35. Elsevier/Academic Press, Oxford, pp. 739-764. ISBN: 0-12-521537-1 [ABSTRACT].
Fagervold, S.K., J.E.M. Watts, H.D. May and K.R. Sowers. 2005. Sequential reductive dechlorination of meta-chlorinated PCB congeners in sediment microcosms by two different phylotypes of Chloroflexi . Appl. Environ. Microbiol. 71: 8085-8090 [ABSTRACT].
Apolinario-Smith,
E., K.M. Jackson, and K.R. Sowers.
2005.
Development
of a plasmid-mediated reporter system for in vivo monitoring of gene
expression in the archaeon Methanosarcina acetivorans.
Appl.
Envion. Microbiol.
71:
4914-4918 [ABSTRACT].
Watts,
J.E.M., S.K.
Fagervold, H.D. May and K.R. Sowers. 2005.
A PCR based specific assay reveals a diverse population of bacteria
within the Chloroflexi associated with the reductive dehalogenation of
polychlorinated biphenyls.
Microbiology UK, 151: 2039-2046 [ABSTRACT].
Miller,
G.S., C.E. Milliken, K. R. Sowers, and H. D. May.
2005.
Reductive Dechlorination of Tetrachloroethene to trans-Dichloroethene and cis-Dichloroethene
by PCB-Dechlorinating Bacterium DF-1.
Environ. Sci. Technol.,
39:2631-2635
[ABSTRACT].
Baxter, B.K., C.D. Litchfield, K.R. Sowers, J.D. Griffith, P. Arora Dassarma and S. DasSarma. 2005. Microbial Diversity of Great Salt Lake. In: N. Gunde-Cimerman, A. Oren, A. Plemenitas (ed.), Adaptation to life at high salt concentrations in Archaea, Bacteria, and Eukarya. Springer Science, Dordrecht, The Netherlands, pp. 9-26.