Genetic control of biosynthesis, as well as the localization and functional role of carotenoids in the chloroplast membranes of plants and algae are briefly discussed.">
This chain type is frequently found in several lipid forms, either isolated or combinedwith other chemical structures. A series of long-chain methylated alkanes (more than 23carbon atoms), saturated or with one double bond, were identified in settlingparticles and surface sediments from Japanese lakes and were shown to beproduced by planktonic bacteria being thus useful molecular markers (). Laboratory experiments havedemonstrated that -alkanes up to C35 may be formed in the laboratoryunder hydrothermal conditions (Fischer-Tropsch-type reactions) from formic acidor oxalic acid ().These results support the theory of the origin of life in hydrothermal systems.
Methoxyalkanes have been identified on bodies or silk of spiders :1-methoxy-16,20,24,28-tetramethylhentriacontane and1-methyl-2,24-dimethyloctacosane ().
It must be noticed that highly branched and unsaturated (2-5 double bonds)isoprenoids are widespread components in marine sediments (review by). The identification of C25 and evenof C30 highly branched isoprenoid alkenes in diatoms () have clearly established that they are the source ofthese compounds found in sediments.
Among the saturated isoprenoids found in geological sediments and oils, the mostfrequent are pristane (2,6,10,14-tetramethylpentadecane) and phytane (2,6,10,14-tetramethylhexadecane). Both compounds can be generateddiagenetically from the phytol side chain of chlorophyll. Pristane may alsoderive from the side chain of tocopherols while phytane is also generated byArchaea.
Carotenoid Biosynthesis and Regulation in Plants - …
Light-regulated expression of the gsa gene encoding the chlorophyll biosynthetic enzyme glutamate 1-semialdehyde aminotransferase in carotenoid-deficient Chlamydomonas reinhardtii cells.
Carotenoid biosynthesis regulatory mechanisms in plants.
To clarify stress response gene expression associated with high carotenoid production, we used Enterococcus gilvus isolated from cow’s raw milk which is able to produce high amount of carotenoid. As stress treatment, E. gilvus cells, which were incubated anaerobically, were shaken (aerobic condition). On the other hand, anaerobic incubation of E. gilvus is continued as non-stress treatment (anaerobic condition). To investigate stress response genes associated with carotenoid production, the gene expression levels of the mevalonate biosynthesis pathway (hmgs and hmgr), the isoprene biosynthesis pathway (mvk, pmvk, mpd, ipi and ispA) and the carotenoid biosynthesis pathway (crtM and crtN) were examined using real-time PCR. Compared with anaerobic condition, all genes excluding hmgs were upregulated in aerobic condition (Fig. 1.). We could show that upregulation of isoprenoid biosynthesis genes occurred under aerobic condition and led to enhancement of carotenoid production. To enhance stress-tolerant LAB, mutagenesis in the isoprenoid biosynthesis pathway is considered to be a useful. Furthermore, LAB with high levels of carotenoid production may contribute to supply fermented products with carotenoid considered as antioxidant.
(1998) Genes and enzymes of carotenoid biosynthesis in plants
Lactic acid bacteria (LAB) is industrial important bacteria because LAB are used in fermented foods and probiotics. The clarification of the stress tolerance mechanism of LAB is beneficial for probiotic and molecular breeding to equip LAB with stress tolerance. The increased stress tolerance of LAB can lead to efficient productivity of metabolites and high survivability in the gut environment. The objective of this study is the clarification of stress response mechanism including carotenoid in LAB considered as novel stress tolerance mechanism in LAB. In general, carotenoid plays role in photo-biosynthesis and antioxidant in plants and microorganisms. A part of LAB belonging to Enterococcus and Lactobacillus have yellow pigment, and the yellow pigment is carotenoid named as diaponeurosporene which can enhance oxidative stress tolerance as well as bile acid and lysozyme. However, the gene expression response of carotenoid and its precursor biosynthesis pathways, such as the isoprene biosynthesis pathway via mevalonate, to oxidative stress is not understood in detail.
Flavonoid Biosynthesis Pathway | Carotenoid | Chloroplast
Back in 2009, researchers were able to demonstrate that was an effective source of vitamin A. This investigation was done with a group of healthy adult volunteers in the USA. The study showed that the β-carotene contained in was highly available and easily taken up into the bloodstream by the human digestive system. While foodstuffs of plant origin are the major contributors of β-carotene in the diet, these are often absent from the diet, for customary and economic reasons. And moreover, conversion of the provitamin A carotenoids contained in them is generally inefficient. Conversion factors for provitamin A carotenoids from various fruits is in the range of 13:1 for sweet potato, 15:1 for carrots, and between 10:1 and 28:1 for green leafy vegetables. With a conversion factor of 4:1 displays a comparatively very favourable conversion ratio. This study was published in the .