I know nothing about the Snowmax, but I do know about cryoprotection
using non-nucleating bacteria. These are a species of Pseudomonas that
outcompetes nucleating bacteria and prevents frost crystal formation,
permitting the fruits to survive to -5C (Crawford, M. 1987. California
field test goes forward. Science 236: 511.).
The soil bacterium Pseudomonas syringae was altered so that it would
retard frost formation on potato and strawberry plants in California,
saving millions, perhaps billions in lost crops (Tangley, L. 1983.
Engineered organisms in the environment? Not yet. BioScience 33:
681-682.; Lewis, R. 1989. Deliberate releases - The coming era of
genetic engineering. Biology Newsletter, W. C. Brown Publ, Fall 1989:
6-7.). These are known as ice minus bacteria.
For crops, the principle involved is prevention of desiccation. Ice
crystals are very hygroscopic and attract water from the cells of the
plant. The nucleating bacteria serve as centers for these ice crystals to
form. The non-nucleating bacteria may be smaller, forming smaller
crystals, or for whatever reason do not form the desiccating crystals.
The same principle is used in many terrestrial frogs in the winter. They
form proteins that make only small crystals and hence avoid cell damage
when the tissues of 60% of the frog's body freeze in winter. (Fascinating
stuff in Marchand's book, Life in the Cold.)
Janice
***********************************
Janice M. Glime, Professor
Department of Biological Sciences
Michigan Technological University
Houghton, MI 49931-1295
jmglime at mtu.edu
906-487-2546
FAX 906-487-3167
***********************************
>> Plantedders,
> The introduction to chapter one in Tortora is about a bacterial
> protein (enzyme?) product in "Snowmax" used in snowmaking machines
> as the "nucleator" to prevent the water supercooling. The protein is
> produced by bacteria from plants native to high altitudes.
> My question: What is the exoprotein's role in the natural
> environment? Some articles suggest it was "genetically engineered"
> and may not be natural.
> It was discovered during research to find a natural product
> to lower the temperature of freezing (I think?) as a method of crop
> frost protection. Some frost protection products now marketed are
> antibacterials to lower (prevent) natural nucleator microbial growth.
> Anyone have any ideas, citations, etc?
>> David
>> Note: cross posted to microed
>
