The Improvement of Milk by Cultivation with Ciliates

¹ B A Biotech, Bustamante 2434, 5 B, RA-1425, Buenos Aires, Argentina
² Dairy Nutraceutical Corp., SE 1410 Bishop Blvd., Pullman, WA 99163
³ B A Biotech, Bustamante 2434, 5 B, RA-1425, Buenos Aires, Argentina, Dairy Nutraceutical Corp., SE 1410 Bishop Blvd., Pullman, WA 99163

The exceptional nutritional values of milk have long been recognized. However, important drawbacks of milk and dairy products are their relatively high cholesterol contents and their low proportion of polyunsaturated fatty acids. Hypersensitivity to milk proteins can also draw the public away from fluid milk consumption. The nonpathogenic ciliate Tetrahymena thermophila has a unique set of enzymes that converts cholesterol into provitamin D₃ and related compounds. It also contains 12 fatty acid desaturases and releases various hydrolases, including proteases, lipases, and phospholipases. We investigated the potential use of these peculiar traits to improve milk by short-term incubation with live ciliate suspensions. We found that cholesterol can be reduced to 50% of its initial content in whole milk by a 12-h period of incubation with T. thermophila cells, mostly by conversion to 7-desaturated cholesterol derivatives, including provitamin D₃. In addition, a considerable increase in -linolenate (18:3, n-6) takes place. The protein profile is markedly changed by proteolysis, with a striking reduction of casein and enhancement in total amino acid content. Despite these changes, no marked alterations in flavor or odor were observed at the end of 12 h of incubation. Thus, Tetrahymena appeared ideally suited to correct for milk drawbacks, making this important source of nutrients more acceptable to the health-conscious public.

Key Words: milk • Tetrahymena • cholesterol • proteolysis

Submitted on September 21, 2000
Accepted on January 16, 2000

This article has been cited by other articles:

				A. D. Nusblat, S. R. Najle, M. L. Tomazic, A. D. Uttaro, and C. B. Nudel C-5(6) Sterol Desaturase from Tetrahymena thermophila: Gene Identification and Knockout, Sequence Analysis, and Comparison to Other C-5(6) Sterol Desaturases Eukaryot. Cell, August 1, 2009; 8(8): 1287 - 1297. [Abstract] [Full Text] [PDF]