Transgenic Animals:Transgenic animals are being developed for a wide variety of applications. In the near future, transgenic animals will be used increasingly in safety evaluation of new pharmaceuticals and accelerating their regulatory approval. The feasibility of producing human pharmaceutical proteins in the milk of transgenic livestock has been established.
As an alternative to cell-culture systems, such livestock appear to be appealing because of high volumetric productivity, low operating costs, capability of posttranslation modification of proteins, and potential for expansion of the producing organism. Bioprocess engineers face numerous technical challenges in converting a transgenic mammary gland system into a commercial prototype for large-scale manufacture of high-market-volume proteins, including the following:
1) Purification techniques for obtaining high-purity proteins that must be recovered and fractionated from a complex mixture of fats, proteins, sugars, and ions, some of which are in colloidal form.
2) Optimization of product stability during recovery.
3) Instrumentation to characterize posttranslation modifications made by the mammary gland "bioreactor."
4) Development of on-line sensors to monitor changes in bioactivity of products during purification.
5) Bioseparations of milk proteins.
In the longer term, transgenic animals might provide a source of tissues and organs for use in transplantation patients. Bioprocess engineering will be needed to design novel equipment to maintain, purify, and store the living tissues without affecting viability or graft response.
The hurdles to be surmounted in developing the necessary genetic tools for systematic pathway engineering are substantial, but basic research at the molecular level will continue to provide improved production strains and novel products, and continued interest in the fundamentals of bioprocessing of milk will help to define separation strategies for this complex biological fluid.
Transgenic Plants:Transgenic plants are capable of generating specialty chemicals or other bioproducts. Special bioprocessing capabilities will then also need to be developed for extracting, concentrating, and purifying such products from plant tissue. This sector of bioprocess engineering might also be important to the prospects of expanding crops or developing new varieties that are rich in fermentable carbohydrates, which are readily used as feedstocks for large-scale manufacturing of specialty and industrial chemicals.
Transgenic tobacco plants have been developed to produce monoclonal antibodies identical in function with the original mouse antibody. Other proteins produced in plants are human serum albumin and enkephalins. Processes to recover and purify proteins from plant-cell extracts will be needed if such systems are commercialized.