1 Comment

The Cain Bugs

by Elio

Pneu­mo­cocci (Strep­to­coc­cus pneu­mo­niae) aren't the most af­fa­ble of bac­te­ria. They make an­timi­cro­bial agents such as bac­te­ri­ocins and bac­te­ri­olysins that are di­rected not, as is the usual case, against other species, but against their own. This phe­nom­e­non, dubbed fratri­cide has been linked to the com­pe­tence sta­tus of the bac­te­ria, that is, to the abil­ity of the bac­te­ria to take up extracel­lu­lar DNA. The killers are com­pe­tent cells, and those that get killed are ones that have not be­come com­pe­tent.

Cain's frat­ri­cide, from Mon­reale cathe­dral. Source

In a re­cent re­view, Clav­erys, Mar­tin and Hå­varstein dis­cuss sev­eral facets of strep­to­coc­cal frat­ri­cide, con­clud­ing that it may well be wide­spread among the strep­to­cocci. Do you want a tele­o­log­i­cal ex­pla­na­tion?  The au­thors spec­u­late that frat­ri­cide may be not only a way to in­crease ge­netic ex­change but also a mech­a­nism for re­leasing vir­u­lence fac­tors that may en­hance the path­o­genic­ity of vir­u­lent strains.

 

Other Posts

  • A Close En­counter of the Eno­log­i­cal Kind

    by John In­gra­ham — Early in my ca­reer, by good for­tune, I en­coun­tered the mal­o­lac­tic fer­men­ta­tion. In­ves­ti­gat­ing it by stan­dard micro­bio­logical meth­ods led to re­sults that changed the way Cal­i­for­nia red wines are made, for the bet­ter most agree. How sat­is­fy­ing it is to think that I was fol­low­ing in the foot­steps of Pas­teur, no less, and his early ca­reer...

  • You Should Be in Films

    by Elio — Scan­ning elec­tron mi­cro­graph of a Staphy­lo­coc­cus biofilm on the in­ner sur­face of a needle­less con­nec­tor. I spent my ca­reer grow­ing bac­te­ria in liq­uid me­dia. I wasn't aware that my bac­te­ria were plank­tonic, any more than the char­ac­ter in Moliere's play Bour­geois Gen­tle­man was con­scious that he had been speak­ing...

  • Heavy-duty Traf­fic, Mi­croscale

    by Christoph — Men­tion "fla­gel­la" and we mi­cro­bio­lo­gists in­stant­ly think of these in­gen­ious ap­pe­nda­ges that bac­te­ri­al cells use to pro­pel them­selves through flu­ids of va­ry­ing vis­co­si­ties (ar­chaea do this, too, with their ar­cha­el­la). We ra­re­ly think of them as an ac­ces­sory to trans­port car­go. Yes "car­go," you read cor­rect­ly, but may­be you re­mem­ber...

  • Ocean's Tini­est Preda­tor – Um, Re­ally?

    by Christoph — Three months ago, I in­tro­duced to this blog "Ocean's Tini­est Preda­tor" based on a very re­cent pa­per by Ka­men­naya et al. (2018) who claimed to have iden­ti­fied Braaru­dosphaera bigelowii, a mem­ber of the pho­to­syn­thetic al­gal clade Hap­to­phyta, as a preda­tor of the abun­dant ma­rine Cyanobac­terium Prochloro­coc­cus. Our reader Benedetto pointed out...

  • In­side Earth, Mi­crobes Ap­proach Im­mor­tal­ity

    by Jen­nifer Frazer — Last De­cem­ber, the Deep Car­bon Ob­ser­va­tory an­nounced an as­tound­ing fact: the mass of the mi­crobes liv­ing be­neath Earth's sur­face amounts to 15 to 23 bil­lion tons of car­bon, a sum some 245 to 385 times greater than the car­bon mass of all hu­mans. That's amaz­ing. It wasn't so long ago we weren't even sure life at depth was pos­si­ble.

1 Comment
Oldest
Newest Most Voted
Paul Orwin
19 years ago

Very in­ter­est­ing re­view. I didn't know about this be­hav­ior be­fore, al­though I have read some of the lit on pneu­mo­coc­cus com­pe­tence. In my class I al­ways make the point that is was very for­tu­nate that Grif­fith chose pneu­mo­coc­cus rather than an­other res­pi­ra­tory pathogen, be­cause nat­ural com­pe­tence is not that com­mon. This story is now be­com­ing less and less true as peo­ple find com­pe­tence in Vib­rio as well (and Bacil­lus long ago). Makes for a good story, though!
The frat­ri­cide is­sue is very, very in­ter­est­ing. I don't know if peo­ple have looked for a frat­ri­ci­dal ten­dency in other or­gan­isms. The com­pet­i­tive bac­te­ri­ocin and lytic en­zyme story was and is very ap­peal­ing in a nu­tri­ent re­stricted en­vi­ron­ment. Still, you can cer­tainly come up with good rea­sons why a frat­ri­ci­dal strat­egy can con­fer an ad­van­tage. In a nu­tri­ent rich en­vi­ron­ment, it is ob­vi­ous — the pop­u­la­tion is about to ex­plode, and you want to have your genes as well rep­re­sented as pos­si­ble. I'm not sure I buy the vir­u­lence ar­gu­ment (it makes more sense to se­crete a vir­u­lence fac­tor; he­molysins are read­ily se­creted, if pneu­molysin isn't, that raises an in­ter­est­ing ques­tion).
A hy­poth­e­sis I didn't see in the re­view was that the frat­ri­ci­dal ten­dency might be part of a tran­si­tion to a ses­sile (biofilm) lifestyle. A re­cent ar­ti­cle in Mol. Mi­cro­biol (Mol Mi­cro­biol. 2006 Sep;61(5):1196–210.) by Og­gioni et al sug­gests co­or­di­na­tion of vir­u­lence, com­pe­tence, and biofilm. This sug­gests the al­ter­na­tive hy­poth­e­sis that the lytic process is in­volved in biofilm mor­pho­gen­e­sis, rather than ge­netic ad­van­tage (anal­o­gous to PCD in eu­kary­otic tis­sue mod­el­ing).
A great deal to mull over!!!

0