Vampirococcus

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Figure 1--Vampirococcus
Vampirococcus cells (red) attached to a Chromatium prey (light green) by the means of electron-dense material [3]

Classification

Higher order taxa

Kingdom: Prokaryotae

  • Domain: Bacteria
    • Phylum: Unknown
      • Class: Unknown
        • Order: Unknown
          • Family: Unknown

As of 2008, "Phylogenetic Analysis of Vampirococcus and Daptobacter has yet to be undertaken...[1]"

Species

  • Genus: Vampirococcus
  • Species: Unknown


Description and significance

Vampriococcus is one of few known predatory prokaryotes. It is a 0.6 micrometer, ovidal bacteria of which no modal forms have been found. It is a gram-negative bacteria that is found in freshwater sulfurous lakes in northern Spain. As an anaerobic epibiont, it attaches itself to the surface of Chromatium a phototropic bacteria, by specific structures, and as it grows and devides by fission, it destroys its prey [2]. The structures used by Vampirococcus to attach itself to its prey could best be described as cytoplasmic "bridges." From these bridges, a connection is established to the prey which allows the Vampirococcus bacterium to degrade the preys cytoplasm [4]


Genomic Structure

"Phylogenetic Analysis of Vampirococcus and Daptobacter has yet to be undertaken (as they have not yet been grown in culture)" [1]. The article goes on to say that Vampirococcus may be related to Deltaproterbacteria and Bdellovibro due to the manor of their growth.


Cell Structure and Metabolism

Vampirococcus attaches itself to the cell wall of species of Chromatium and reproduces while "sucking out" the cellular components of Chromatium[2]. It's environment also suggests that it can also anaerobic conditions. Vampirococcus appears, via electron microscopy, to have a specialized ‘‘holdfast’’ structure that may act as a conduit of host cell molecules[4].

Ecology

Vampirococcus has only been found in lakes in Northeastern Spain, having been studied in Lake Estanya and Lake Ciso. These lakes are characterized as sink holes and have high calcium sulfate and anhydriteconcentrations. Due to a large production of hydrogen sulfide within the sediment, the lakes are anoxic. Lake Estanya is 12 m deep and Lake Ciso is 20 m deep, making them relatively shallow bodies of water and light penetrates to the thermocline in both. The availability of light coupled with the anoxic conditions caused by the hydrogen sulfide makes the lakes ideal for the growth of phototrophic sulfur bacteria. [2] Chromatium, also known as "purple sulfur bacteria", flourish in these conditions due to their ability to oxidize sulfide and produce sulfur. Because Chromatium is the only prey of Vampirococcus, the Vampirococcus population follows where the population of Chromatium is most abundant.[3]

Figure 2--Vampirococcus
Vampirococcus cells (small cells) attached to a Chromatium prey, with the outer membrane penetrated and darker plaque [2]

Pathology

While not a pathogenic species, Vampirococcus is a predatory bacteria that attaches to Chromatium in order to reproduce. It attaches itself to the cell wall of Chromatium and divides while degrading the host cytoplasm.

Current Research

Important current research concerning Vampirococcus has been proposed by researchers attempting to use the bacterium as an anti-tumor agent. In nature, Vampirococcus preys on fresh-water purple sulfur bacteria known as Chromatium minus. The researchers believe that the target tumors, which are mainly anaerobic and contain copious amounts of cysteine similar to Chromatium, can be targeted by the predatory Vampirococcus cells. As an epibiont organism, the Vampirococcus will remain on the outside of the cell that it is attacking, and only multiply when attached to a prey cancer cell. Following the degradation of the cancer cells, the Vampirococcus will be unable to proliferate in the patient’s body due to their epibiont nature. The benefit of the epibiont nature of Vampirococcus is twofold: as aforementioned, the bacterium will be unable to proliferate following the degradation of the cancer cells, but prior to that, will continuously divide with the presence of the cancer cells, thus eliminating the need for multiple therapy treatments [5]. In theory, this seems a plausible means to anti-cancer therapy.

Cool Factor

This is one of the few know predatory in the world, along with Ensifer and Bdellovibro. However, each of the species "feed" on different sources. The bdellovibro feeds on a wide range of bacteria and can be found in many different environments [4]. However, Vampirococcus only feeds on Chromatium and has only been found in Lake Estanya and Lake Ciso.



Sources

[1] Whitworth, David E. "Myxobacteria [electronic resource] : multicellularity and differentiation" Washington, DC : ASM Press, c2008.

[2] Ricardo Guerrero,Carlos Pedros-Alio Et al. Predatory prokaryotes: Predation and primary consumption evolved in bacteria, Evolution and Microbiology, Vol. 83, pp. 2138-2142, April 1986

[3] Edouard Jurkevitch,Predatory Behaviors in Bacteria—Diversity and Transitions, Microbe Volume 2, Number 2, 2007

[4] Martin, Mark O. Journal of Molecular Microbiology and Biotechnology. Predatory Prokaryotes: An Emerging Research Opportunity, Vol. 4, Issue 5, pp. 467–477, 2002

[5] Cueto, Michelle, Apernico, Paul Et al. Treating Cancer Through Inovation, Bridgeport, CT. February 2010.