PRODUCTION OF KETOCAROTENOIDS (ASTAXANTHIN AND ADONIXANTHIN) USING A NOVEL
CAROTENOID-SECRETING BACTERIAL SPECIES
(B-11617)
Principal Investigator:
Joseph Hirschberg, Department of Genetics, Institute of Life Sciences, The
Hebrew University of Jerusalem
Commercial Advantages:
Carotenoids are widely distributed natural pigments that are responsible
for many of the yellow, orange and red colors seen in living organisms.
They have important commercial uses as coloring agents in the food
industry, as feed and food additives, in cosmetics and as provitamin A
precursors. The red ketocarotenoid pigment astaxanthin (3,3'-dihydroxy-beta
,beta-carotene-4,4'-dione) is found to be very common in many marine
animals and algae. The function of astaxanthin as a powerful antioxidant in
animals has been demonstrated. Astaxanthin is a strong inhibitor of lipid
peroxidation and has been shown to play an active role in the protection of
biological membranes from oxidative injury. Astaxanthin also has
chemopreventive effects as it significantly reduced the incidence of
induced urinary bladder cancer in mice. It has also been demonstrated that
astaxanthin exerts immunomodulating effects by enhancing antibody
production. Astaxanthin enhances in vitro antibody production to T-de
pendent antigens without facilitating polyclonal B-cell activation. The
complete biomedical properties of astaxanthin remain to be elucidated, but
initial results suggest that it could play an important role in cancer and
tumor prevention, as well as eliciting a positive response from the immune
system. Astaxanthin is the principal carotenoid pigment of salmonids and
shrimps and imparts attractive pigmentation in the eggs, flesh and skin.
The red coloration of the salmonid flesh contributes to consumer appeal and
therefore affects the price of the final product. Animals cannot synthesize
carotenoids and they acquire the pigments through the food chain from the
primary producers - marine algae and phytoplankton. Those grown in
intensive culture usually suffer from suboptimal color. Consequently,
carotenoid-containing nourishment is artificially added in aquaculture, at
considerable cost to the producer. Astaxanthin is used in aquaculture as a
feed additive for farmed salmon, trout, sh
rimp and sea bream. It is used also as feed additive for poultry where it
furnishes a deeper color of the yolk of the eggs, a preferred
characteristic by many consumers, and is considered beneficial to the
health and fertility of chickens and hens. Consumer preference, which has
recently been reflected in legislation in some countries requires all
colorants added to animal feeds be derived from natural sources. The known
process for production of natural astaxanthin are expensive and impractical
from the industrial point of view. Natural (3S,3'S) astaxanthin is limited
in availability. It is commercially extracted from some crustacea species
in a very costly production. The (3R,3'R) stereoisomer of astaxanthin is
produced from the yeast Phaffia. Synthetic astaxanthin, comprising a 1:2:1
mixture of the (3S,3'S)-, (3S,3'R)- and (3R,3'R)-isomers is manufactured by
Hoffman-La Roche and sold at a high price. No industrial process for
production of adonixanthin is known. We have identified
a novel coccoid bacterial species belonging to the genus Paracoccus. This
novel bacterium, named Paracoccus marcusii MH1, produces and actively
secretes ketocarotenoids such as adonixanthin and astaxanthin.
Current Status:
The present invention relates to a process for production of carotenoids,
such as, but not limited to, lycopene, beta-carotene, echinenone,
canthaxanthin, beta-cryptoxanthin, zeaxanthin, adonirubin, adonixanthin and
astaxanthin, using a bacterial species that produces and secretes these
carotenoids. The present invention provides a novel bacterial species of
the genus Paracoccus, Paracoccus marcusii strain MH1, that secretes
substantial amounts of carotenoids to its growth medium during its life
cycle (as opposed to decomposition processes). None of the bacterial
species known to science secretes carotenoid-containing vesicles to the
growth medium. This feature of P. marcusii makes it suitable for industrial
purposes in production processes that are based on continuous extraction
from cultured cells. Cells of Paracoccus marcusii strain MH1 are cocci to
short rods, 1 to 2 by 1 to 1.5 m in size. They appear mainly in pairs and
short chains or clusters of up to 4-5 bacteria. Cells are n
onmotile, and do not form spores. Strain MH1 stained gram-negative.
Colonies on agar were smooth, flat, brightly orange colored. Optimum
temperature for growth is 25-30C. Doubling time in the standard growth
medium at the optimal temperature is approximately 2 h. Detailed
description of Paracoccus marcusii strain MH1 appeared in: Harker, M.,
Hirschberg, J. and Oren, A. "Paracoccus marcusii sp. nov., an orange
gram-negative coccus" Int. J. Sys. Bacteriol. (in press). Growing P.
marcusii in suspension cultures in a nutrient medium including sources of
carbon, nitrogen and inorganic substances, it is possible to recover an
individual carotenoid pigment or a mixture of carotenoid pigments from
either the bacterial cells, or from the medium where it is secreted from
the bacteria in small vesicles and inclusion bodies. Paracoccus marcusii
strain MH1 produces and secretes free (3S,3'S)-astaxanthin and free
adonixanthin whose absolute configurations are the same as those of the
naturally occ
urring all-trans ketocarotenoids and, therefore, astaxanthin and
adonixanthin produced by the present process are industrially valuable. The
wild-type strain of Paracoccus marcusii MH1 produces various carotenoids
which comprise approximately 80% of ketocarotenoid. The carotenoids that
are secreted to the medium are found in small vesicles that contain 87% of
free adonixanthin and 8% of free astaxanthin.