Biomedical Engineering Reference
In-Depth Information
C
HAPTER
2
The Genetics and Molecular
Biology of Carotenoid
Biosynthesis in Mucorales
Catalina Sanz, Mahdi Shahriari and Arturo P. Eslava*
Abstract
Carotenoids are synthesized by most photosynthetic organisms like cyanobacteria,
algae and plants and some non-photosynthetic such as certain fungi, yeasts and
bacteria. Animals and humans cannot synthesize them and acquire them through
diet. The usefulness of carotenoids in nature is very diverse. In oxidative photo-
synthetic organisms carotenoids are essential compounds with different functions,
the protection against photo-oxidation being the most important. In animals,
carotenoids and their derivatives are involved in different biological processes,
such as vitamin A in nutrition, retinol used as antenna pigment, rhodopsin in
the retinal cells, retinal pigment used as an antenna and retinoic acid to regulate
various cellular processes. In humans, carotenoids taken in the diet may protect
against cancer, chronic diseases and immune illnesses. A number of carotenoids
are used in the animal and human food industries to intensify the colour of salmon
or trout fl esh, egg yolk and human food colorant. The market for commercial
carotenoids has been mainly based on products of chemical synthesis, but today
the interest in carotenoids of biological origin is growing because of the public
concern over the safety of artifi cial food colorants. This preference for carotenoids
of natural origin has led to a search for natural sources of such compounds. In this
sense, some Mucorales as
Blakesleea trispora
,
Mucor circinelloides
and
Phycomyces
blakesleeanus
are being studied as carotenoid producers. In these fungi, all the
enzymatic activities needed to synthesize β-carotene are encoded by two closely
linked genes divergently orientated in a cluster like organization that seems to
be characteristic of Zygomycetes. The biosynthesis of carotene is much more
conserved than its regulation, as is often the case in the evolution of metabolic
