Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2005
Publication Date: 8/1/2005
Citation: Simon, H. M., C. E. Jahn, L. T. Bergerud, M. K. Sliwinski, P. J. Weimer, D. K. Willis, and R. M. Goodman. 2005. Cultivation of mesophilic soil crenarchaeotes in enrichment cultures from plant roots. Appl. Environ. Microbiol. 71:4751-4760. Interpretive Summary: The archaea are a recently discovered kingdom of bacteria that inhabit many different environments ranging from hot springs, to the oceans, to agricultural soil. These bacteria grow very slowly and are difficult to culture in the laboratory. The detailed study of archaea is therefore limited to those strains that are easily grown in the laboratory. This paper describes the first successful attempt to grow archaeal bacteria belonging to the division Crenarchaeota. These bacteria are potentially important to agriculture due to their extensive association with plant roots. We were able to grow strains of Crenarchaeota in a laboratory medium containing extracts from tomato roots. This work presents the framework for beginning the understanding the contribution of archaeal bacteria to plant health.
Technical Abstract: Because archaea are generally associated with 'extreme' environments, detection of nonthermophilic members belonging to the archaeal division Crenarchaeota over the last decade was unexpected; they are surprisingly ubiquitous and abundant in non- extreme marine and terrestrial habitats. Metabolic characterization of these nonthermophilic crenarchaeotes has been impeded by their intractability toward isolation and growth in culture. From studies employing a combination of cultivation and molecular phylogenetic techniques (PCR-single-strand conformation polymorphism, construction and sequence analysis of 16S rDNA clone libraries, fluorescence in situ hybridization, and real-time PCR), we present evidence here that one of the two dominant phylotypes of Crenarchaeota that colonizes the roots of tomato plants grown in a Wisconsin field soil is selectively enriched in mixed cultures amended with root extract. Clones recovered from enrichment cultures were found to group phylogenetically with sequences from clade C1b.A1. This work corroborates and extends our recent findings indicating the diversity of the crenarchaeal soil assemblage is influenced by the rhizosphere and that mesophilic soil crenarchaeotes are found associated with plant roots, and provides the first evidence for growth of nonthermophilic crenarchaeotes in culture.