Difference between revisions of "Symbiobacterium thermophilum"

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Genus Symbiobacterium thermophilum

Revision as of 01:02, 14 November 2007

A Microbial Biorealm page on the genus Symbiobacterium thermophilum Genus Symbiobacterium thermophilum


Higher order taxa

Bacteria; Firmicutes; Lactobacillales; Symbiobacterium Domain; Phylum; Class; Order; family [Others may be used. Use NCBI link to find]


NCBI: Taxonomy

Genus species Symbiobacterium thermophilum

Description and significance

Symbiobacterium thermophilum is a Gram-negative and tryptophanase-positive thermophilic bacterium found in a commensal submerged culture that was derived from compost. This bacterium is characterized by a marked growth dependence on microbial commensalism; it does not grow by itself under standard culture conditions; however, when cocultured with Bacillus sp. strain S, it propagates up to 5 × 108 cells/ml. Molecular phylogeny using the 16S ribosomal DNA (rDNA) sequence has indicated that S.thermophilum belongs to an unknown taxonomic group in the Gram-positive bacterial cluster. The current 16S rDNA database content suggests that the presence of this bacterium and related organisms is still poorly recognized, probably due to the technical problems involved in its isolation. Meanwhile, our ecological study has revealed the potential phylogenetic diversity and the wide distribution of Symbiobacterium and related bacteria in the natural environment.

Genome structure

The S. thermophilum genome is characterized by the widespread insertion of class C group II introns, which are oriented in the same direction as chromosomal replication. The genome has many membranes transporters, a number of which are involved in the uptake of peptides and amino acids. The genes involved in primary metabolism are largely identified, except those that code several biosynthetic enzymes and carbonic anhydrase. The organism also has a variety of respiratory systems including Nap nitrate reductase, which has been found only in Gram-negative bacteria. Overall, these features suggest that S.thermophilum is adaptable to and thus lives in various environments, such that its growth requirement could be a substance or a physiological condition that is generally available in the natural environment rather than a highly specific substance that is present only in a limited niche. The genomic information from S.thermophilum offers new insights into microbial diversity and evolutionary sciences, and provides a framework for characterizing the molecular basis underlying microbial commensalism. The random sequencing strategy indicated that S.thermophilum has a circular chromosome consisting of 3566135 bp with 68.7% G + C (Figure 1) and no extrachromosomal element. The GC skew clearly indicated the direction of replication and the position of the replication origin (oriC). The oriC contains AT-rich repeated sequences, which probably serve as the binding sites for DnaA encoded immediately downstream from oriC.

Cell structure and metabolism

Interesting features of cell structure; how it gains energy; what important molecules it produces.


Habitat; symbiosis; contributions to the environment.


How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Current Research

Enter summarries of the most rescent research here--at least three required


[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by student of Dr. Kirk Bartholomew