Biomedical Engineering Reference
In-Depth Information
visual cues which are especially important in sexual relationships (Olson
and Owens 1998).
Carotenoids are produced by many non-photosynthetic bacteria and
fungi (Armstrong 1997, Sandmann and Misawa 2002), but not by animals,
many of which require them from their food. 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 for the opsins of
microorganisms and retinoic acid to regulate various cellular processes. In
animals they are also used to increase the colouration of some species of
industrial interest such as salmon and are generally used in various products
such as food dyes for human consumption.
In humans, carotenoids taken in the diet may protect against cancer,
chronic diseases and immune illnesses because of their antioxidant and
protective roles against free radicals and highly reactive compounds from
the normal cell metabolism or environment (Delefuente 1991, Giovannucci
et al. 1995, Avalos and Cerdá-Olmedo 2004, Namita and Negi 2010).
β-carotene specifi cally infl uences gene expression of certain oncogenes,
induces differentiation and inhibits the multiplication in infected cells
(Fomenko et al. 1997). Lycopene is associated with protection against
prostate cancer (Giovannucci et al. 1995, Rao et al. 1999, Van Breeman et
al. 2002) and decreased risk of heart disease (Rimm et al. 1993). Lutein and
Zeaxanthin act as fi lters for protection of retinal cells and their consumption
is associated with the prevention of some of the leading causes of blindness,
like xerophthalmia, cataracts or macular degeneration (Brown et al. 1999,
Moeller et al. 2000). The contribution of β-carotene as a source precursor
of vitamin A is highly recommended to prevent vision problems caused
by lack of vitamins that the population from disadvantaged parts of the
world suffers every year.
Carotenoid Production in Fungi
A number of carotenoids are used in the animal and human food
industries, for instance to intensify the colour of salmon or trout fl esh, egg
yolk and human food colourant. 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 colourants. This preference for
carotenoids of natural origin has led to a search for natural sources of
such compounds (Hirschberg 1999).
There are several carotenoid-producing fungi. The carotenoids produced
by them are similar to those produced by photosynthetic organisms,
though much simpler and often accumulating a single major carotenoid.
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