Thermophilic Acidobacteria

Figure: Scanning and transmission electron micrographs of Acidobacteria isolate K22. Scale bar = 1 µm.

Figure: Scanning and transmission electron micrographs of Acidobacteria isolate K22. Scale bar = 1 µm.

We have cultivated thermophilic Acidobacteria from geothermal soils within the Taupo Volcanic Zone (TVZ)(1).

Isolate K22 represents one of the first thermophiles cultivated from the environmentally widespread and abundant Acidobacteria phylum. There are only five described species in this phylum, although members of the "Group 1" Acidobacteria have recently been grown with increasing frequency(2).

Members of the Acidobacteria are frequently detected in high-temperature habitats such as deserts, and hydrothermal terrestrial and marine systems(3-5). However, with the exception of an enrichment culture containing a phototrophic acidobacterium growing at temperatures up to 66ºC(6), thermophilic Acidobacteria have not been previously grown in the laboratory. This species is an obligately aerobic organotroph that utilises complex polysaccharides, such as xylan and xanthan, and simple sugars such as mannose, glucose and xylose.

We are currently undertaking research to fully characterise this strain. We are particularly interested in the electron diffuse region at the poles of the cells (see figure) which we speculate may be a PHA (polyhydroxyalkanoate) accumulation. PHA's are linear polyesters that can be used in the production of bioplastics

We are currently completing a thorough physiological and metabolic characterisation of this species.

References

  1. Stott, M.B., Crowe, M.A., Mountain, B.W., Smirnova, A.V., Alam, M., and Dunfield, P.F. (2008) Isolation of novel bacteria, including a candidate division, from geothermal soils in New Zealand. Environ. Microbiol. 10:2030-2041.
  2. Janssen, P.H. (2006) Identifying the dominant soil bacterial taxa in libraries of 16S rRNA and 16S rRNA genes. Appl Environ Microbiol 72: 1719-1728.
  3. 3. Gundlapally, S.R., and Garcia-Pichel, F. (2006) The community and phylogenetic diversity of biological soil crusts in the Colorado Plateau studied by molecular fingerprinting and intensive cultivation. Microbial Ecol 52: 345-357.
  4. Glamoclija, M., Garrel, L., Berthon, J., and Lo?pez-Garci?a, P. (2004) Biosignatures and bacterial diversity in hydrothermal deposits of Solfatara Crater, Italy. Geomicrobiol J 21: 529-541.
  5. Lopez-Garcia P., Duperron, S., Philippot, P., Foriel, J., Susini, J., and Moreira, D. (2003) Bacterial diversity in hydrothermal sediment and epsilonproteobacterial dominance in experimental microcolonizers at the Mid-Atlantic Ridge. Environ Microbiol 5: 961-976.
  6. Bryant, D. A., Costas, A.M.G., Maresca, J.A., Chew, A.G.M, Klatt, C.G, Bateson, M.M., Tallon, L.J., Hostetler, J.,Nelson, W.C., Heidelberg, J.F., and Ward, D.M. (2007) Candidatus Chloracidobacterium thermophilum: An aerobic phototrophic Acidobacterium. Science 317: 523-526.