Light‐harvesting and light‐protecting pigments in simple life forms

Abstract

Photosynthesis is the basis of life on the earth and the development of the vast range of simple organisms existing today can often be traced back to the earliest geological times. Most life forms depend directly or indirectly on the synthetic processes which harvest the sun's energy, utilising a range of pigments such as the chlorophylls and carotenoids, which not only determine the colour of each organism, but often also serve a protective role against the adverse effects of ultraviolet radiation. Recent research has elucidated the detailed photochemical mechanisms and the complex nature of the light-harvesting pigment-protein complexes. This review covers algae and fungi and their symbiotic forms in lichens and corals, particularly with respect to the pigments they synthesise and the commercial uses to which these and other metabolites have been (and may in the future be) put.

Inclusion ofPalmaria palmata(red seaweed) in Atlantic salmon diets: effects on the quality, shelf-life parameters and sensory properties of fresh and cooked salmon fillets

“…wileyonlinelibrary.com/jsfa Table 3. Effect of dietary Palmaria palmata (PP) on surface lightness (L*), redness (+a*), greenness (−a*) and yellowness (b*) values of fresh salmon fillets (n = 3) stored in modified atmosphere packs (60% N 2 /40% CO 2 ) for up to 15 In general, the surface redness (a*) values of PC salmon fillets increased as a function of storage time ( Table 3). The increased surface redness due to synthetic astaxanthin deposited in the PC salmon fillets resulted in a red/pink colour.…”

“…Ten amino acids essential for salmon growth and protein structure are all present in P. palmata . Palmaria palmata also contains a variety of fat‐soluble carotenoids, including high levels of lutein (yellow), α ‐ and β ‐carotene (reddish yellow) as well as chlorophyll a / b (mid green to olive green) . Carotenoids are isoprenoid molecules that aid in the absorption of sunlight and protect cells from oxidative stress by quenching singlet oxygen .…”

“…12,13 Palmaria palmata also contains a variety of fat-soluble carotenoids, including high levels of lutein (yellow),and -carotene (reddish yellow) as well as chlorophyll a/b (mid green to olive green). 14,15 Carotenoids are isoprenoid molecules that aid in the absorption of sunlight and protect cells from oxidative stress by quenching singlet oxygen. 4 The carotenoid content of P. palmata varies seasonally, depends on postharvest treatment and is generally higher than that in other seaweed species.…”

Biosynthesis and synthesis of natural colours

“…In plants, the main light-absorbing pigment is chlorophyll a, although chlorophyll b and c are also present in smaller proportions in different plant species, together with various other important coloured secondary metabolites, particularly the carotenoids. These pigments not only augment light absorption, particularly in the middle visible wavebands, but may also have a photoprotective effect on the plant [5]. The number of individual bacteriochlorophylls is considerable, but the principle one, bacteriochlorophyll a, is found in both purple bacteria and green sulphur bacteria [26].…”

“…Over 3 billion years ago, the very earliest life forms, such as the single‐celled, coloured bacteria (descendants of which still live in volcanic pools and by ‘smoker’ vents in the ocean depths), had to exist in very severe conditions of temperature, pH, intense short wave [ultraviolet (UV)‐C] solar radiation and, originally, in the absence of oxygen [5]. Extremophile archaebacteria range in colour from red to purple and, using bacteriorhodopsin, accomplished a form of photosynthesis that did not generate oxygen but methane.…”