The first genetically engineered product for human consumption, an enzyme expected to be of wide use in making cheese, was approved Friday by the Food and Drug Administration.
In the decision, which came after 28 months of review, the agency said a bioengineered form of the enzyme rennin--which traditionally has been extracted from calves' stomachs as part of a mixture called rennet and used by cheese makers to curdle milk--presented no safety hazard and could be used in dairy products.
Officials of the dairy industry, which spends about $100 million on rennet each year, welcomed the new product as an alternative to the natural form of the enzyme. Rennet is of uncertain purity and has soared in price in recent years.
It also seems to set a precedent for the number of companies seeking FDA approval for other enzymes made by genetically altered bacteria.
But federal officials and some biotechnology experts said the time the agency took to approve the application and the unusually detailed explanation the FDA gave for the approval indicate that genetic engineering of foods remains a sensitive issue and that the agency intends to scrutinize closely future applications for more exotic bioengineered products.
The new kind of rennin is produced by biotechnology's workhorse bacteria, a species called Escherichia coli. The bacteria were altered by implanting in them the cow gene carrying the blueprints for rennin. Since all cells read the same genetic code, the bacteria, now carrying so-called recombinant DNA, make rennet identical to the rennin calves make.
The product, also known as chymosin, is used in the first stages of cheese making, where an ounce can cause 50 gallons of milk to thicken into curdles and whey.
In comparison to traditional rennet, recombinant chymosin is purer, since the process of extracting rennet from the stomachs of veal calves leaves the preparation with a significant percentage of other proteins that can not be filtered out.
The product's manufacturer--the New York-based Pfizer Inc.--said it had agreed to sell the product to several major U.S. and foreign cheese makers, promising a lower price than the natural version, which has risen from $50 to $85 a gallon in the past year.
There are at least five other recombinant enzyme petitions before the FDA, three for different forms of rennin and two for an enzyme used as a thickening agent in food preparation.