Abramo C Ottolenghi
aottolen at magnus.acs.ohio-state.edu
Sun Sep 25 15:34:22 EST 1994
In article <1994Sep23.122434.1981 at msus1.msus.edu>,
<mol13 at msus1.msus.edu> wrote:
>I have just noticed the thread on BHI medium and I would
>like to offer my speculation concerning as one person put
>it "what is its magic ingredient?".
>As my work concerns the ability of various neuroendocrine
>hormones to influence the growth and pathogenicity of bacteria,
>notably gram-negative, I have always found it curious that the
>question of BHI's ability to support bacterial growth has not
>been investigated to a high degree. At the ASM meeting in New
>Orleans a couple years ago I brought up this point during my
>presentation when I discussed the ability of neuroendocrine hormones
>associated with stress to greatly increase the growth of E. coli as
>well as P. aeruginosa (the medium I use is a serum-supplemented media).
>Could it be more than just coincidence that the two major components
>of BHI, namely calf brains and beef hearts, come from the two highest
>innervated organs in the body? Do various neuroendocrine hormones
>survive the processing steps as well as subsequent autoclaving? The
>answer is most definitely yes (we have even seen norepinephrine peak in
>HPLC-EC we have run on autoclaved BHI).
>I have in fact called the product quality manager at Difco and asked
>rather naively how is BHI made. His answer was that you didn't need
>a degree in rocket science -- you take 100 lbs. of beef hearts and 100
>lbs. of sheep brains, squish 'em down (his words), filter, dehydrate and
>sell it. I then asked if he ever sees differences in growth properties betwee
>various lots of BHI and his answer is all the time. The lots just have to
>meet some minimum requirement.
>Considering the fact that the hearts and brains are coming from different
>slaughterhouses where the animals are undergoing a very stressful procedure
>you may be ending up with lots of organs exhibiting different levels of
>neuroendocrine hormones which eventually make it to your lab. And by
>the way, media derived from plant material also contains numerous
>hormones since plants themselves are great reservoirs of such neuroendocrine
>hormones that we usually only associate with mammalian species.
>One final thing, and then I'll get off my soapbox, can one assume that the
>bacteria growing happily in BHI (where everything it can want is provided)
>are the same as bacteria in a host where numerous selection pressures are
>operative? Just remember the decades-long known difference between in vivo
>and in vitro passaged bacteria in terms of virulence.
>Department of Biological Sciences
>Mankato State University
>e-mail: MOL13 at msus1.msus.edu
Very, very interesting. Never thought of it. Makes sense.
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