The Lactose Intolerance Clearinghouse Has Moved.

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Saturday, August 01, 2009

Lactase from the Antarctic?

Lactase is the enzyme that digests lactose. You hear that a lot. I say that a lot. But it's not as simple as that sentence makes it out to be.

Lactase is not a thing, a simple protein. There are lots of lactases, or at least lots of variations in the basic protein. Each animal's lactase is slightly different. And the yeasts and fungi and bacteria that also manufacture lactase make a zillion more variants.

Each of the variants digests lactose, true. That's the definition of lactase. But each works best, has its highest activity levels, at different temperatures and at different pH values.

That's hugely important. The lactase we manufacture is designed to work best in our small intestines because in nature that's the only place it ever needs to work. Then human ingenuity came along. We wanted lactase for people who didn't make lactase. That's a problem. Few people would consent to having lactase injected directly into their bowels before each meal. Swallowing a pill is the only realistic way to take lactase. A swallowed pill has no choice but to go through the stomach before entering the small intestine. The stomach has particularly high acidity. Human lactase wouldn't work if swallowed, but the lactase from a fungus called Aspergillis oryzae has exactly the properties needed, an optimum pH of 4.5-5.5, a stable range of 3.0-7.0 and an optimum temperature of 37C (98.6F) or body temperature. All lactase pills are based on the lactase from this fungus.

That's great. Now, don't let the food scientists rest on these laurels. Tell them they have to find a lactase that will work in the chilly confines of a refrigerator and in the different pH of milk to create lactose-free milks. A dairy yeast named Kluyveromyces lactis happens to manufacture lactase that has these properties. And that the lactase that is used in lactase pills.

K. lactis has its own limitations. It won't work at the freezing point of 0C or 32F. You'd think a bacteria found in Antarctica might not mind the cold as much.

You'd be right. If you read through the heavy science of this press release from you'll see the connection.

[W]e present a new beta-D-galactosidase as a candidate to be applied in the above mentioned biotechnological processes. The gene encoding this beta-D-galactosidase has been isolated from the genomic DNA library of Antarctic bacterium Arthrobacter sp. 32c...

Although, the maximum activity of the enzyme was determined at pH 6.5 and 50degreesC, 60% of the maximum activity of the enzyme was determined at 25degreesC and 15% of the maximum activity was detected at 0degreesC.

Conclusions: The properties of Arthrobacter sp. 32c beta-D-galactosidase suggest that this enzyme could be useful for low-cost, industrial conversion of lactose into galactose and glucose in milk products and could be an interesting alternative for the production of ethanol from lactose-based feedstock.

A process for better lactose-free products. I'll be looking to see if this makes it into industrial production at any time soon.

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