I’m curious about the study.  E. coli (wild type) can be grown using any single amino acid as the sole carbon source.  Are you feeding with labeled glutamic acid?  It’s hard to say that with a straight face since the number of mutant E. coli strains is huge and I don’t know the metabolic properties of the specific strain. I’m sure there’s even variety within the STEC family of strains.

I ask because, if you mean you want to measure d2H of glutamic acid, there is a technical hitch.  Hot acid hydrolysis followed by derivatization essentially mixes glutamine with glutamic acid.

Is it known that five minutes of boiling kills the bugs and denatures the stx?  Maybe I’m a coward, but I’d boil it a longer.

On Mon, Jun 7, 2021 at 7:24 PM Marilyn Fogel <[log in to unmask]> wrote:

https://link.springer.com/article/10.1007/s00442-020-04730-9

and

https://www.pnas.org/content/113/32/E4648.short

We've published H in amino acids in these two papers--and have several more manuscripts ready for submission. It works very well.

To get back to this, the E. coli strain that uses glutamate (our target AA) needs a BSL2 safety cabinet. It needs to be killed before removing from the cabinet since it produces toxins.

We'll process it as usual once dead.

Marilyn

Marilyn L. Fogel

Distinguished Emerita Professor of Geoecology

Dept. of Earth and Planetary Sciences

University of California Riverside

Riverside, CA, USA

https://isotopequeen.blogspot.com/

On Mon, Jun 7, 2021 at 3:56 AM Fred Martin Kaaby <[log in to unmask]> wrote:

I think altering the pH or osmotic pressure (salt) would "pop" most bacterias just as well as heating.

Just a non-related question. How do you analyze specific amino acids for C and H?
Since I am looking into capillary electrophoresis it easily comes into mind here, have someone tried CE-IRMS for the analysis of amino acids, proteins etc?

Fred

-----Original Message-----
From: Stable Isotope Geochemistry <[log in to unmask]> On Behalf Of Tabor, Neil
Sent: søndag 6. juni 2021 18:59
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] effect of "heat killing"?

Or Hg(II)?

On 6/6/21, 11:24 AM, "Stable Isotope Geochemistry on behalf of Max Coleman" <[log in to unmask] on behalf of [log in to unmask]> wrote:

    [EXTERNAL SENDER]

    Marilyn

    If the need is to just to kill them, why not use an old fashioned metal ion bactericide, e.g. Ag, Cu or Zn?

    Good luck

    Max

    –-------------------------------
     Max Coleman
    Senior Research Scientist
    NASA Jet Propulsion Lab, Caltech
    +1 818 393 6353, cell: +1 818 687 7704
    [log in to unmask]
    –-------------------------------

    > On 5 Jun 2021, at 14:25, Marilyn Fogel <[log in to unmask]> wrote:
    >
    > Colleagues,
    >
    > We're doing an experiment with a toxic strain of E. coli. In order to simplify processing the sample, I've been asked if boiling at 100°C for 5 minutes would alter isotope signals.
    >
    > We're analyzing compound specific amino acids for C and H. I'm hesitant to try this, somehow.
    >
    > Any experience? Your thoughts?
    >
    > Marilyn Fogel