E. coli competence

Abramo C Ottolenghi aottolen at magnus.acs.ohio-state.edu
Thu Sep 22 15:29:54 EST 1994

In article <00984D01.F2E01EE0.80 at hal.hahnemann.edu>,
 <mcgeed at HAL.HAHNEMANN.EDU> wrote:
>From:    MX%"mcgeed at hal.hahnemann.edu" 21-SEP-1994 14:31:35.05
>To: MX%"microbiology at net.bio.net"
>Subj:    E.coli competence
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>From: mcgeed at hal.hahnemann.edu
>Subject: E.coli competence
>Date: 21 Sep 1994 11:04:59 -0700
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>From:    HAL::MCGEED       21-SEP-1994 13:52:50.90
>To: MX%"microbiology at net.bio.net"
>Subj:    E. coli competence
>    You bring up an excellent point about cell-cell communication.  There
>is a well-documented literature on the communication of bioluminescent
>bacterial cells with one another as the cell density increases.  The
>bioluminescent bacteria Vibrio harveyi and Vibrio fischeri increase
>dramatically under aerobic conditions during mid-log phase of growth, due to
>the increase in a compound known as autoinducer.  As the name suggests, cells
>secrete the compound into the extracellular environment and the compound then
>acts on a receptor molecule (LuxR) which enhances the bioluminescence operon
>(lux).  Interestingly, the autoinducer from V. fischeri does not induce
>bioluminescence in V. harveyi and vice versa; i. e. the autoinducers in these
>species are distinct compounds.  The autoinducers are small organic molecules
>with an amino acid analog (one is called beta-hydroxybutyryl homoserine
>lactone; I forget the name of the other).
>    A simple way to test for the possible presence of autoinducer in
>E. coli, one would grow up the bugs to mid-log phase, remove all cells from th
>media, and then add a known amount of E .coli to this broth and the same amoun
>to a fresh broth.  If the buggers grow faster in the first broth, then it is
>likely that autoinducer(s) are made in E. coli.
>    Still another Gram (-) bacteria [bioluminescent bacteria are Gram (-)]
>-Pseudomonas aeruginosa- also has been shown to produce autoinducer (I believe
>this is Barbara Iglewski's work), although I don't know much about this case.
>    Isn't this fascinating that these buggers REALLY communicate with one
>another as a group effort?  From an evolutionary standpoint, one might
>speculate that advancement to the eucaryotic realm may, in part, be due to the
>selective advantage that some cells in a population have due to production of
>    Perhaps others could elaborate further?...I've already taken up too
>much time!
>David McGee
>Medical College of Pennsylvania and Hahnemann University
>Dept. Microbiology and Immunology
>e-mail:  mcgeed at hal.hahnemann.edu
>phone: 215-762-8275
>David J. Mcgee
>MCGEED at hal.hahnemann.edu

 I have a number of questions relating to this paper.  It seems to me that the 
peaks in competence could be related to the cell cycle.  It can not be 
determined from the paper if the starting inoculum was from an overnight 
culture or what.  If the culture was stationary at the beginning one might
expect "near" synchrony for some generations. Vic Norris in a series of papers 
(one such  is in J. Theoretical biol. 154:91-107, 1992 makes the point that the
phospholipids of the membrane are different at the point of membrane curvature 
(such as the septation sites).  It is conceivable that the increased competence
is due to different phospholipid composition of the membrane which would also 
bring a different transition temperature and in turn in some way change the way
the membrane acts during temperature shock.  This might have an effect on the
entry of DNA into the cell.

A. Ottolenghi. Dept. Medical Microbiology and Immunology, Ohio State.
aottolen at magnus.acs.ohio-state.edu

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