Food Biochemistry and Food Processing

56 Part I: Principles

de novo biosynthesis of the carotenoids lycopene, -
carotene, and astaxanthin in C. utilisusing cloned
bacterial genes that encode enzymes of the biosyn-
thetic pathway. They used four genes (crtE, crtB,
crtI, crtY) from Erwinia uredovoraand two genes
(crtZ, crtW) from Agrobacterium aurantiacumfor
construction of four different plasmids. The plas-
mid pCLR1EBI-3 contained crtE, crtI, and crtB,
required for the production of lycopene (Fig. 3.14a).
For synthesis of -carotene, the plasmid pCRAL-
10EBIY-3 contained the genes crtY, crtI, crtE, and
crtB (Fig. 3.14b). A dual plasmid system with
pCLEIZ1 containing crtE, crtI, and crtZ and
pCLBWY1 containing crtW, crtY, and crtBwas
used to produce astaxanthin (Fig. 3.14c,d). In order
to integrate these genes into the yeast chromosome,
the plasmids were linearized by restriction digest
and transformed into C. utilisby electroporation.
The resultant transgenic yeast produced significant
amounts of lycopene (1.1 mg/g dry weight), -
carotene (0.4 mg/g dry weight), and astaxanthin (0.4
mg/g dry weight), in quantities similar to amounts
found in microorganisms that naturally produce
these carotenoids (Miura et al. 1998). These results
indicate that C. utilishas a great potential for use in
large-scale production of commercially important
carotenoids.

DETECTION METHODS IN FOOD

BIOTECHNOLOGY

Biotechnology plays an important role in maintain-

ing the safety of the food supply. The development

of reliable methods to ensure the traceability of

genetic material in the food chain is of great value to

food manufacturers and consumers. Consumer con-

fidence in food biotechnology will increase if better

traceability methods are in place. Modern biotech-

nology tools are also applied to develop sensitive,

reliable, fast, and cheap methods for detection of

harmful pathogenic organisms such as E. coli

O157:H7 and the infectious agent for mad cow dis-

ease.

TRANSGENEDETECTION

Accomplishments in food biotechnology require

continuous development of new products and their

successful commercialization through consumer

acceptance. One of the greatest demands made by

consumer groups as a prerequisite for their support

of transgenic plant use, is the development of reli-

able methods of detection of the transgene in human

food products (James 2001). But as the number of

genetically modified organisms (GMOs) approved

Figure 3.14.Lycopene, -carotene, and astaxanthin plasmid constructs.