Tiny prey stalking murderers!

Bdellvibrios growing inside a host cell (Sockett, 2009)

We were not ready for you. Not sure we ever would have been. We were looking to isolate bacteriophages that prey on gram negative bacteria like you. Instead we found these slower growing plaques on lawns of Pseudomonas that was you[10]. So what if you can bore into other bacteria, use their macromolecules and finally kill them to release more of yourselves. Virus do that. You’re a living, respiring cell. You should have stronger character! But I guess its hard to fit morality into a tiny cells like yours. Bdellovibrio, you’re just about the most diabolical bacteria ever.

Because your way of life was so strange and perverse to us, we studied your developmental stages. We recognize the little ‘attack’ cells (that move at an amazing 60 – 160 um/s in liquid) that you fashion yourselves into when you’re looking to bore into an unassuming fellow bacteria. But we also know that you can use slower guiding motility (15 – 20 um/s) on sold surfaces to find prey[4]. Some of your close deltaproteobacteria cousins (Myxobacteria) hunt in packs and secrete extracellular enzymes to digest prey. But you hunt alone and when you find prey, you invade their peptidoglycan layer[8]. We hear the host bacteria transcriptionally “screaming” by upregulating stress response genes and cell wall repair genes[3]. But we can do little else as we watch with horror as you form bdelloplasts of undivided filaments in the preiplasm of other gram-negative bacteria and suck out their bodily fluids, finally exit through a pore in the dead host membrane[2].

So, we sequenced your large genome and pretend we know a little more about you. You think you’re so cool because you’re an enigma wrapped in a puzzle. Tiny cells (.5um) with an unusually large genome (3,782,950 bp)? Live by preying on other bacterial cells and having ready access to their DNA but no evidence of horizontal gene transfer ? No ATP transport proteins to get energy from your prey? And no quorum sensing??[6] Are you fucking kidding me? Every other bacteria does it. And it would really benefit you to know how much prey is around. But no. You’re above that. You don’t even want to talk to each other, forget about other bacteria. I’ve never heard of a more self important pesky prokaryote!

And it turns out you can live and divide in a saprophytic cycle in a totally host-independent fashion[7]. At least viruses that prey on bacteria can’t divide outside them. You on the other hand, can do just fine even with out hosts. (Don’t even try and deny this. We found the full complement of genes that let you produce ATP through glycolysis and oxidative respiration[6].) So is this just some kind of extreme sport? That’s just ridiculous. In an attempt to diminish our awe for your ridiculous invincibility, we tried to find bacteriophages that would do to you what you do to other bacteria. And we did. Except, it turns out that once you’ve infected another bacteria, these phages have a hard time getting into you[11]. And no, preying on cells is not an acceptable way to evade phages. Fight your own battles. Grow a better cell wall or something. I know plenty of other bacteria that live inside other cells that don’t kill their hosts (I’ll introduce you to Wolbachia someday).

Also, what is the deal with odd number of progeny? How do you not understand the simple rules of bacterial fission? One cell divides to give 2 and two cells divide to give 4 and so on. Just because you developed some way to synchronously septate once you gorged yourselves on all the available cytosol doesn’t mean you can go around releasing odd numbers of offspring from a single infection of a cell[1]. Don’t think you can get away with it because you’re so tiny. It took us a while, but we got you on camera doing what you do best, murdering other gram-negative bacteria to release more of yourselves.

The more of you tiny non-HGTing fuckers we find, we shudder to think that why you haven’t taken over the gram-negative bacterial world[8]… yet. And in this post-species age that you and your prokaryotic cousins have very quickly ushered in, we gave up on naming you all and just call you Bdellovibrio and like organisms (BALOs). So we continue to study you, and knock out genes to see how you manage to be so amazingly efficient at sucking the life out of other cells. We learn about your type IV pilli that you use for infection[5]. We learn about how the motor flagella necessary for your life cycle[2]. We pretend we want to use the knowledge of your plundering pilli and muderous motors to kill other bacteria[12] but in reality, we are just unable to fathom how and why you do what you do.

You fast-swimming, cellwall-boring, bdelloplast forming tiny little freaks, I’m on to you. So don’t give me that shit of how your discovery was serendipitous. You (and all your prokaryotic friends) are just out to blow our lowly eukaryotic brains.

References

  1. Fenton AK, Kanna M, Woods RD, Aizawa SI, Sockett RE. Shadowing the actions of a predator: backlit fluorescent microscopy reveals synchronous nonbinary septation of predatory Bdellovibrio inside prey and exit through discrete bdelloplast pores. J Bacteriol. 2010 Dec;192(24):6329-35.
  2. Flannagan RS, Valvano MA, Koval SF. Downregulation of the motA gene delays the escape of the obligate predator Bdellovibrio bacteriovorus 109J from bdelloplasts of bacterial prey cells. Microbiology. 2004 Mar;150(Pt 3):649-56.
  3. Lambert C, Ivanov P, Sockett RE. A transcriptional “Scream” early response of E. coli prey to predatory invasion by Bdellovibrio. Curr Microbiol. 2010 Jun;60(6):419-27.
  4. Lambert C, Fenton AK, Hobley L, Sockett RE. Predatory Bdellovibrio bacteria use gliding motility to scout for prey on surfaces. J Bacteriol. 2011 Jun;193(12):3139-41. Epub 2011 Apr 22.
  5. Mahmoud KK, Koval SF. Characterization of type IV pili in the life cycle of the predator bacterium Bdellovibrio. Microbiology. 2010 Apr;156(Pt 4):1040-51. Epub 2010 Jan 7.
  6. Rendulic S, Jagtap P, Rosinus A, Eppinger M, Baar C, Lanz C, Keller H, Lambert C, Evans KJ, Goesmann A, Meyer F, Sockett RE, Schuster SC. A predator unmasked: life cycle of Bdellovibrio bacteriovorus from a genomic perspective. Science. 2004 Jan 30;303(5658):689-92.
  7. Seidler RJ, Starr MP. Isolation and characterization of host-independent Bdellovibrios. J Bacteriol. 1969 Nov;100(2):769-85.
  8. Sockett RE. Predatory lifestyle of Bdellovibrio bacteriovorus. Annu Rev Microbiol. 2009;63:523-39. Review.
  9. Starr MP, Baigent NL. J Bacteriol. Parasitic interaction of Bdellovibrio bacteriovorus with other bacteria. 1966 May;91(5):2006-17.
  10. Stolp H, Starr MP. Bdellovibrio bacteriovorus gen. et sp. n., a predatory, ectoparasitic, and bacteriolytic microorganism. Antonie Van Leeuwenhoek. 1963;29:217-48.
  11. Varon M, Levisohn R. Three-membered parasitic system: a bacteriophage, Bdellovibrio bacteriovorus, and Escherichia coli. J Virol. 1972 Mar;9(3):519-25.
  12. Wolfe AJ. Sighting the alien within: a new look at Bdellovibrio. J Bacteriol. 2010 Dec;192(24):6327-8. Epub 2010 Oct 15.
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