EFFECTS OF IRON AND LIGHT STRESS ON THE BIOCHEMICAL COMPOSITION OF ANTARCTIC PHAEOCYSTIS SP. (PRYMNESIOPHYCEAE). II. PIGMENT COMPOSITION

Abstract

A strain of Phaeocystis sp., isolated in the Southern Ocean, was cultured under iron‐ and light‐limited conditions. The cellular content of chlorophyll a and accessory light‐harvesting (LH) pigments increased under low light intensities. Iron limitation resulted in a decrease of all light‐harvesting pigments. However, this decrease was greatly compensated for by a decrease in cell volume. Cellular concentrations of the LH pigments were similar for both iron‐replete and iron‐deplete cells. Concentrations of chlorophyll a were affected only under low light conditions, wherein concentrations were suppressed by iron limitation. Ratios of the LH pigments to chlorophyll a were highest for iron‐deplete cells under both light conditions. The photoprotective cycle of diato/diadinoxanthin was activated under high light conditions, and enhanced by iron stress. The ratio of diatoxanthin to diadinoxanthin was highest under high light, low iron conditions. Iron limitation induced synthesis of 19′‐hexanoyloxyfucoxanthin and 19′‐butanoyloxyfucoxanthin at the cost of fucoxanthin. Fucoxanthin formed the main carotenoid in iron‐replete Phaeocystis cells, whereas for iron‐deplete cells 19′‐hexanoyloxyfucoxanthin was found to be the main carotenoid. This shift in carotenoid composition is of importance in view of the marker function of both pigments, especially in areas where Phaeocystis sp. and diatoms occur simultaneously. A hypothesis is presented to explain the transformation of fucoxanthin into 19′‐hexanoyloxyfucoxanthin and 19′‐butanoyloxyfucoxanthin, referring to their roles as a light‐harvesting pigment.

Phytoplankton community response to Fe and temperature gradients in the NE (SERIES) and NW (SEEDS) subarctic Pacific Ocean

“…However, Chl-a to C (biomass) ratio may change with time during the incubation because Chl-a quota is affected by Fe nutrition. Chl-a quota is lower under Fe-limited than that under Fe-replete conditions (Guikema and Sherman, 1983,Greene et al, 1992, Kudo et al, 2000, McKay et al, 1997, van Leeuwe and Stefels, 1998.…”

Comparison of different filter types on chlorophyll-a retention and nutrient measurements

“…Hence the chlorophyll(-a) content in algae is influenced by many abiotic factors like light, temperature and nutrients (Van Leeuwe and Stefels, 1998;Marañón et al, 2000;Barlow et al, 2002;Lalli and Parsons, 2002;Malinsky-Rushansky et al, 2002;Sosik and Olson, 2002), we recommend not to increase the probability of a wrong measurement by using an unsuitable filter. We were able to show how various the results of different filter types with same pore sizes can be.…”

Effects of Environmental Factors and Nutrient Availability on the Biochemical Composition of Algae for Biofuels Production: A Review

“…High concentrations of iron in cultures of Chlorella vulgaris were observed to increase the lipid content [195]. Decrease in iron content reduces carotenoid composition [185,196].…”