A Microbial Biorealm page on the Planctomyces
Higher order taxa:
Bacteria; Planctomycetes; Planctomycetacia; Planctomycetales; Planctomycetaceae
Planctomyces brasiliensis, P. limnophilus, P. maris, P. sp.
Description and Significance
Planctomyces is a marine bacterium that can be found in various habitats around the world. Planctomycetes in general are intriguing because they are the only free living bacteria known to lack peptidoglycan in their cell walls.
Although no Planctomyces bacteria have been sequenced, a physical map of the circular chromosome of Planctomyces limnophilus DSM 3776 was made using pulsed-field gel electrophoresis techniques. From this it was deduced that the size of the genome is 5.204 Mb as determined by restriction enzyme digests - this is significantly larger than the 4.2 Mb that was determined by thermal renaturation methods. Relatively large genomes are thought to be necessary for adaptation to changing conditions in nutrient-poor or fluctuation environments; since the P. limnophilus was isolated from a eutrophic lake, which could be considered a demanding environment, it has been suggested that a number of the genes in its genome assist in environment adaptation (Ward-Rainey et al. 1996).
Cell Structure and Metabolism
Planctomyces generally have a spherical shape and uniform crateriform structure distribution all over the cell surface. Their cell walls lack peptidoglycan; they are instead stabilized by the protein sacculus with disulfide bonds. Planctomyces, as well as the rest of the planctomycetes, go through budding reproduction. The planctomycetes studied so far seem relatively resistant to streptomycin, which inhibits protein synthesis.
Planctomyces brasiliensis was originally isolated from a hypersaline lake in Brazil, but it, as well as other species of Planctomyces, can be found in many different types of geographical regions and habitats. It has been found in freshwater, saltwater, acid bog water, cattle manure, garbage dumps, and rice paddies. Though they tend to flourish in the summer and fall back in the winter. This is partially due to the need for Planctomyces need for algae, which is not as prevelant in winter. Planctomyces and other planctomycetes are also often encountered in tissue cultures of aquatic invertebrates. Several studies of planctomycetes have included isolating Planctomyces, Pirellula, Gemmata, or related organisms from giant tiger prawn (Penaeus monodon) samples. Both the samples of the healthy prawn postlarvae and the samples of the postlarvae infected with monodon baculovirus (making them more susceptible to diseases and bacterial infections) had planctomycete populations. Planctomycetes may exist free living or associated with invertebrates in marine habitats rich with organic nutrients (Fuerst et al. 1997).
Brümmer, I. H. M. , A. D. M. Felske, and I. Wagner-Döbler. Diversity and Seasonal Changes of Uncultured Planctomycetales in River Biofilms. Applied and Environmental Microbiology, September 2004, p. 5094-5101, Vol. 70, No. 9.
Chouari, Rakia, Denis Le Paslier, Patrick Daegelen, Philippe Ginestet, Jean Weissenbach, and Abdelghani Sghir. 2003. "Molecular evidence for novel Planctomycete diversity in a municipal wastewater treatment plant." Applied and Environmental Microbiology, vol. 69, no. 12. American Society for Microbiology. (7354-7363).
Fuerst, John A., Heather G. Gwilliam, Margaret Lindsay, Agnieszka Lichanska, Craig Belcher, Joan E. Vickers, and Philip Hugenholtz. 1997. "Isolation and molecular identification of planctomycete bacteria from postlarvae of the giant tiger prawn, Penaeus monodon." Applied and Environmental Microbiology, vol. 63, no. 1. American Society for Microbiology. (254-262).
Ward-Rainey, Naomi, Fred A. Rainey, Elizabeth M. H. Wellington, and Erko Stackebrandt. 1996. "Physical map of the genome of the Planctomyces limnophilus, a representative of the phylogenetically distinct planctomycete lineage." Journal of Bacteriology, vol. 178, no. 7. American Society for Microbiology. (1908-1913).