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ARS Home » Midwest Area » Urbana, Illinois » Global Change and Photosynthesis Research » Research » Publications at this Location » Publication #295912

Title: Mechanism of growth interaction involving electron shuttling between Pseudomonas stutzeri and Anaeromyxobacter dehalogenans

item Chee Sanford, Joanne
item Connor, Lynn
item SANFORD, R - University Of Illinois

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/1/2014
Publication Date: 6/1/2015
Citation: Chee Sanford, J.C., Connor, L.M., Sanford, R.A. 2015. Mechanism of growth interaction involving electron shuttling between Pseudomonas stutzeri and Anaeromyxobacter dehalogenans. Proceedings of International Society for Microbial Ecology and Ecological Society of America Research 2015 Joint Symposium. 39:35-42.

Interpretive Summary: Carbon cycling is a key microbial process in all soils. The prevalence of Anaeromyxobacter dehalogenans as a microbial population in metagenomic surveys of a variety of soils, especially agricultural soils, suggest their role in metabolic food webs to be greater than previously thought. This study extends from initial findings that a growth relationship exists between the common soil bacterium Pseudomonas stutzeri and numerically abundant A. dehalogenans. We grew the two populations as co-cultures using labeled carbon sources that only P. stutzeri is able to utilize to ascertain the presence of requred electron transport mechanism that requires the presence of A. dehlaogenans. The results further support the hypothesis that P. stutzeri hasa direct energy-generating interaction with Anaeromyxobacter, whereby gaining energy for growth through a chemical electron shuttle and the cell membrane respiratory machinery of Anaeromyxobacter. Such an interaction would be ecologically beneficial to microbes like P. stutzeri, and may explain in part the role of metabolic versatile A. dehalogenans and other related organisms in natural environments that shift dynamically in redox state and electron acceptor pools. The significance of this research demonstrates a potentially unique type of interaction in microbial communities that explains the growth of multiple species that otherwise would not be predicted, and may contribute significantly to the carbon cycle in soil and other natural environments than what is currently known.

Technical Abstract: An anaerobic enrichment culture derived from agricultural soil microcosms was established using 2,6-dichlorophenol (DCP) as an electron acceptor and acetate as an electron donor. Using 13C-acetate and DNA-SIP, 13C-DNA was enriched in 16S rRNA genes from populations of Anaeromyxobacter dehalogenans and Pseudomonas stutzeri. We isolated each population separately and demonstrated that A. dehalogenans strain DCP-18 was able to respire 2,6-dichlorophenol and 2-chlorophenol, while P. stutzeri strain DCP-Ps1 could not under the original culture conditions. Growth of strain DCP-Ps1, however, was not inhibited with DCP present while using nitrate as an electron acceptor. To examine the apparent growth dependency of strain DCP-Ps1 on the presence of strain DCP-18, we cultured each strain alone, and in co-culture together with only 2,6-DCP and acetate. In both culture conditions, strain DCP-18 increased 96-fold from an initial concentration of 9.74 x 104 per ml. In contrast, P. stutzeri strain DCP-Ps1 only grew when the strain DCP-18 was present, increasing by 39-fold from an initial cell concentration of 1.93 x 104 per ml. These growth results and the assimilation of 13C from acetate by strain DCP-Ps1 in the SIP experiment with DCP as an electron acceptor only occurred when active halorespiring A. dehalogenans strain DCP-18 was present. The results suggest the presence of a mechanism for strain DCP-Ps1 to transfer electrons from acetate oxidation to strain DCP-18, whereby allowing growth of the former strain and the use of the electrons by the latter strain to reduce 2,6-DCP.