Article by Raffi M. Turian
A Biochemical Engineering Concentration at the B.S.
degree level has been established by the Department of Chemical
Engineering. The program was introduced
in recognition of the fact that chemical engineers, having played an important
historical role in the development of bioprocessing
in the chemical, food, beverage, pharmaceutical and environmental cleanup
areas, continue to occupy significant positions in such endeavors today. Microbial or enzymatic processes have long
been recognized as one of the two principal means of chemical transformation in
the chemical and pharmaceutical industry; the other being thermochemical. The biochemical engineering concentration
provides graduates with the B.S. degree in Chemical Engineering with broader
career options. These include enhanced
employment opportunities in the pharmaceutical, bioprocess, brewing and food
processing industries, in addition to the traditional employment opportunities
in the chemical and petrochemical fields.
Students receiving a B.S. degree with the biochemical concentration will
also have broader choices in graduate degree programs in chemical and other
engineering fields as well as in professional programs such as pharmaceutics
and medicine. The formal introduction of
such a degree option
is especially timely given the revolutionary advances in
molecular biology which have taken place in recent decades, and the commercial
exploitation of such techniques as recombinant DNA which have been
realized. It is important for chemical
engineering students to be exposed to these new technologies, and to develop an
appreciation for the potentialities and promise residing at the intersection of
applied microbiology and chemical engineering.
The development of the process for mass production of
penicillin in the early forties, at the height of World War II, stands as a
significant milestone in the contribution of chemical engineering to biotechnology. The process developed for the production of
penicillin, and other broad-spectrum antibiotics, in large quantities
represented a new paradigm in the field.
Before the advent of antibiotic manufacture, existing fermentations for
food, beverages, food-additive products and supplements, such as citric acid,
could be carried out on a large scale with little fear of contamination, both
because process conditions were such that they inhibited the intrusion of undesirable microorganisms and also because required purity
standards for such products are not stringent. Large-scale antibiotic manufacture required
the establishment of fermentation processes capable of handling enormous
volumes of nutrient media and air (since these fermentations are aerobic) under
absolutely aseptic conditions, and the development of product bioseparation and purification processes capable of
extracting a highly temperature-sensitive and fragile product present in a
spent nutrient broth at forbiddingly low concentrations. The adaptation of submerged-culture, deep-tank
fermentation for antibiotic manufacture required the following: 1. the effective sterilization of enormous
volumes of nutrient media -typically in the range of two hundred thousand
gallons and containing temperature-labile essential nutrients-, large volumes
of air and also large-scale equipment,
2. the efficient removal of
metabolic heat, the enhancement of oxygen transfer through provision of
adequate mixing, and the overall maintenance of optimum conditions for growth
of the microorganism and for bioproduct formation,
3. the recovery and purification of a
fragile, temperature-labile product dispersed in exceedingly low concentration
in a spent broth containing mycelial organisms (the
mold) with a strong tendency to clog filter cloths, and 4. the special design
of fermentation vessels, seals, and controls appropriate to strict maintenance
of absolutely sterile conditions over production cycles lasting days or
weeks. Special design and operational
procedures were needed to meet the absolute purity standards that are the
hallmarks of modern pharmaceutical manufacture.
In a November 20, 2004 obituary of Jasper Kane, a biochemist with Chas. Pfizer & Company, who in 1942 adapted concepts from a Pfizer mold fermentation process for biosynthesis of citric acid to propose the penicillin deep-tank fermentation process, The New York Times quotes David Wilson, author of the book “In Search of Penicillin” (Knopf, 1976) as writing: “It is the biggest single failing of the myth about penicillin that it ignores the technological breakthrough of deep fermentation, a breakthrough that was every bit as vital to the successful development of penicillin as any of the more dramatic laboratory work.” Despite skeptics at the time, broad-spectrum antibiotic synthesis went from a doze by doze basis to a production level of more than 45 million units within about nine months of the March 1943 opening of the new plant proposed by Kane. The 2004 flu vaccine crisis has given momentum to the idea of a deep-tank cell-culture process replacing the dauntingly labor intensive, and contamination-prone, process in which millions of eggs must be individually inoculated and processed. Submerged-culture, deep-tank fermentation for commercial-scale antibiotic production exemplifies technology at the intersection between chemical engineering and applied microbiology.
Among the various courses
offered, students choosing the Biochemical Engineering Concentration are
required to take the course Ch.E 422: Biochemical
Engineering. The broad purpose of this
course is to provide a unified presentation of the essential elements of bioprocessing.
Specific topics covered include quantitative treatments of bioreactor
design, nutrient formulation and design, nutrient and air sterilization
technologies and equipment design, transport processes and specifically oxygen
transfer involved in bioreactor operation, and bioseparations
and product purification. To provide a
meaningful foundation for these topics, the course also includes detailed study
of the various classifications of microorganisms and their varied structures
and growth requirements, the chemicals involved in cells and their growth,
enzyme and microbial-growth kinetics, growth kinetics involving defined as well
as complex media or multiple substrates, substrate utilization and bioproduct formation kinetics, culture isolation and
selection, DNA replication and
recombinant DNA techniques, and discussion of industrial bioprocesses
involving both pure and mixed cultures.
Thus Ch. E. 422 provides students with a broad unified overview of
biochemical/bioprocess engineering.
However, the underlying objective of the overall program is to expose
chemical engineering students to the modern concepts, the methodologies and the
culture of the biological sciences and the exciting new discoveries in
molecular biology. Accordingly, students
choosing the Biochemical Engineering Concentration are also required to take
lecture and laboratory courses in biosciences, including microbiology and
biology. Through such exposure we hope
that students will discover pertinent ideas and lessons from the life sciences,
which they will apply in their work and in productive interactions with
industrial and/or applied microbiology coworkers.