Week #7 - Social and Ethical Issues (due 3/4)
Thousands of years ago, people living in the Middle East discovered that when they added a tiny quantity of extract from the inner lining of the fourth stomach of a freshly killed calf to cows milk, the milk turned to cheese. In the twentieth century, biochemists isolated and characterized the responsible agent: an enzyme named chymosin. The enzyme is encoded by a single gene that is expressed only in animals that chew their cud and only before weaning. Until just two decades ago, cheese makers had to use this animal product as an essential component of the cheese-making process. Then, using the tools or recombinant DNA technology, biotechnologists cloned the cow chymosin gene in a bacterial expression vector, making it possible to produce fully functional chymosin in a culture of cloned bacteria. In 1990, chymosin produced in this way became the first approved product of recombinant DNA technology to enter the US food market. Unlike calf chymosin, recombinant cow chymosin can be standardized; it can also be inexpensively produced, and it doesn't require the killing of any animals. Purified calf chymosin and bacterially produced chymosin are indistinguishable in their structure and enzymatic activities. By 2004, over 90% of the cheese on supermarket shelves in the US, Europe, and most other countries around the globe were produced using recombinant chymosin.
Chr. Hansen, the Danish company that produces recombinant chymosin under the trademark of ChyMax, claims in their promotional literature that it is "nature's own enzyme for clotting milk and a natural ingredient for the food industry." What is the definition of the term natural? Is it appropriate for a company to use this term to describe a protein made from a mammalian-specific gene inside bacterial cells? Does it matter that the purified chymosin proteins from the calf's stomach and from cloned bacteria are structurally and functionally identical? How important is the process relative to the product in assessing something's naturalness?