Posted on 03/22/2007 12:54:42 PM PDT by bd476
Food fight: Cheese bacteria fight off viral attacks
By Julie Steenhuysen
Reuters
CHICAGO Mar 22, 2007 - Scientists have found a way to ensure starter cultures used to make cheese can ward off attacks from bacteria-eating viruses -- a finding that could mean the difference between a great Gouda and wasted milk.
Attacks by viruses known as phages pose a particular problem for companies like Danish food ingredient maker Danisco, whose starter cultures are used in about half of all the ice cream and cheese produced in the world.
"Phages are one of the major causes of product failure for the food industry, especially in the dairy industry," said Philippe Horvath, a scientist at Danisco's laboratory in Dange-Saint-Romain, France.
The tiny viruses that infect bacteria enter the cell and rapidly replicate until the cell ruptures, spreading the virus in a series of repeating cycles.
"It's an explosive propagation," he said in a telephone interview.
Horvath and colleagues at Danisco have discovered how to harness bacteria's own natural defense mechanisms to produce phage-resistant bacteria. They reported their results in Friday's issue of the journal Science.
The study helps explain the role of a new family of repetitive sequences in the genome of bacteria called CRISPR sequences. They resemble some of the DNA sequences in the phages.
"LET NATURE DO THE WORK"
In computer models, scientists proposed that the CRISPR sequences allow bacteria to hijack a bit of the virus' genetic code, helping it to fight off attacks.
"Our results are the first biological demonstration that CRISPR provides a resistance against phages," Horvath said.
The researchers tested their theory on Streptococcus thermophilus, a bacteria used in making cheese and yogurt.
They were able to manipulate the DNA within the bacteria, adding a new spacer that gave it immunity against the attacking virus.
"We replicated what happens naturally in the lab using molecular biology tools. We've also shown that when we artificially take them out, the bacteria loses resistance," Horvath said.
Although the Danisco researchers could use the finding to produce genetically modified starter cultures for cheese and yogurt, they will not, out of respect for concerns over genetically modified organisms or GMOs in foods.
"We'll let nature do the work for us by simply challenging the bacterium with the phage," he said.
Then, they will simply choose the resistant bacteria for their cell cultures, he said.
Diana, thank you for posting the interesting article about blue cheese. Suddenly I'm hungry for salad with blue cheese dressing. :-)
:)
"Suddenly I'm hungry for salad with blue cheese dressing."
That's a daily craving in this household, LOL! :)
And how about that Sardinian maggot cheese?
http://en.wikipedia.org/wiki/Casu_marzu
I make a soup using Maytag Blue that is absolutley wonderful. It's called Iowa Blue Satin Soup from Paul Prudhomme's "Seasoned America" cookbook.
Lot's of seasonings, butter, onion, chicken stock, heavy cream, delicious Maytag Blue and more.
It's cheese soup on steroids! LOL
Thanks to LibFreeOrDie, here is a cheese I will not crave anytime soon. If you blow up the photo at the link and look closely, you can just see what makes this cheese so special in the upper left portion of the cheese.
LOLOL!
Um, I'll pass on that too, LOL!
Makes ya wonder how many bottles of wine were drunk by the the first taste tester for that cheese.
minus one the
RISPR Provides Acquired Resistance Against Viruses in Prokaryotes
This PDF file includes Materials and Methods Figs. S1 to S5 References
That's all the freebies.
Thank you for the informative links, neverdem!
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