Significance of Mn and Fe for growth of coastal marine diatom Thalassiosira weissflogii (original) (raw)
Related papers
Latin American Journal of Aquatic Research, 2012
The estuarine diatom Thalassiosira weissflogii (Fryxell & Hasle, 1977) has been widely used as live feed in aquaculture. The growth rate and biochemical composition of microalgae are highly influenced by environmental factors such as, light, salinity and nutrient availability. Salinity is difficult to control in some shrimp laboratories specialized in larvae production, because these laboratories depend upon the levels measured in estuaries or coastal lagoons, which are the water sources for larvae culture. The present study evaluated the effect of different salinities (25, 30, 35, 40, 45 and 50 psu), on the growth and chemical composition of T. weisflogii at three culture phases, under laboratory conditions. The highest growth rate and maximum cell density were found at 25 psu. Decrease in size and striking changes in morphology of the cells were observed at the higher salinities and drastic changes occurred at 50 psu. Protein and carbohydrate content were higher at low salinities (25 and 30 psu) during the stationary phase. The lipid production was higher at low salinities, but diminished as the phase changes occurred; in contrast, the lipid content was unaffected by the growth phase at higher salinities (≥35 psu). The higher growth rate and better biochemical composition were obtained at 25 and 30 psu.
Latin American Journal of Aquatic Research, 2012
The estuarine diatom Thalassiosira weissflogii (Fryxell & Hasle, 1977) has been widely used as live feed in aquaculture. The growth rate and biochemical composition of microalgae are highly influenced by environmental factors such as, light, salinity and nutrient availability. Salinity is difficult to control in some shrimp laboratories specialized in larvae production, because these laboratories depend upon the levels measured in estuaries or coastal lagoons, which are the water sources for larvae culture. The present study evaluated the effect of different salinities (25, 30, 35, 40, 45 and 50 psu), on the growth and chemical composition of T. weisflogii at three culture phases, under laboratory conditions. The highest growth rate and maximum cell density were found at 25 psu. Decrease in size and striking changes in morphology of the cells were observed at the higher salinities and drastic changes occurred at 50 psu. Protein and carbohydrate content were higher at low salinities (25 and 30 psu) during the stationary phase. The lipid production was higher at low salinities, but diminished as the phase changes occurred; in contrast, the lipid content was unaffected by the growth phase at higher salinities (≥35 psu). The higher growth rate and better biochemical composition were obtained at 25 and 30 psu.
Limnology and Oceanography, 2013
We investigated the link between iron (Fe) limitation and intracellular dimethylsulfoniopropionate (DMSP) concentration in two oceanic phytoplankton species, the diatom Thalassiosira oceanica and the diazotrophic cyanobacterium Trichodesmium erythraeum. Dimethylsulfoxide (DMSO) concentrations were also measured in Fe-replete and Fe-limited T. oceanica. Fe limitation decreased the growth rates of T. oceanica and T. erythraeum by 33-fold and 3.5-fold, respectively and increased intracellular DMSP (DMSP p) concentrations by 12-fold (from 2.8 to 33.7 mmol L cell 21) and by 45-fold (from 0.05 to 2.27 mmol L trichome 21), respectively. Intracellular dimethylsulfoxide (DMSO p) concentrations in T. oceanica increased by 5-fold under severe Fe limitation, from 0.78 mmol L cell 21 in Fe-replete cells to 3.86 mmol L cell 21. The increase in DMSP p and DMSO p under Fe limitation provides support for the role of these sulfur compounds as antioxidants. Under severe Fe limitation, the large increase in DMSP p : C and DMSP : chlorophyll a (Chl a) ratios for both T. oceanica (by 16-and 40-fold, respectively) and T. erythraeum (by 18-and 145-fold, respectively) places these species above the range of values generally attributed to diatoms and cyanophytes. Comparison of these values with in situ results, such as those from Fe fertilization experiments, suggests that the decrease in DMSP p : Chl a and DMSO p : Chl a that is generally observed with alleviation of Fe limitation may be partly related to decreases in DMSP p and DMSO p in individual species. The role of diatoms and diazotrophic cyanobacteria in the biogeochemical cycle of dimethylsulfide and associated sulfur compounds in Fe-limited oceanic environments should not be overlooked.
J Phycol, 1986
Growth ratf, crllular manganese concentration, and manganeif uptake kiiiftics were measured as functions of the free manganese ion concentration iji the medium for tu'o centric diatoms. Thalassiosira oceanica Hasle, isolated from a low-manganese oceanic environment, was capable of better growth at low manganese ion concentrations than T. pseudonana Hasle and Heimdal, isolated from high-manganese estxtarine waters. This was due to ihe oceanic species' greater ability to accumulate manganese at low free itm concentrations and to grow well at lower cellular manganese concentrations. Manganese uptake in both species followed cla.<i.ucal saturation kinetics, and V'^^, hut nol K,, varied with the manganese ion concenlration in the growth medium. The K, of manganese Uptake for T. oceanica (10 '" M) was one-snrnth of that for T. pseudonana. accounting [or Y. oceanica'.i greater ability to accumulate manganese at low free ion concentrations. V^^, appeared to he under negative feedback control in both species and six-to tu'elve-fold variations in this parameter alhnved cells to regulate cellular manganese at nearly constant values at manganese ion Concentrations in the x'icinit\ of and somewhat below KT hf range in free mangane.se ion concentrations mrr which Tegulation occurred tras d iff emit for the tu'o species, and coincided with the range in free manganese ion concentrations of the natural habitat of each species.
Enhancement of the reactive iron pool by marine diatoms
Marine Chemistry, 2008
Short term (2 days) laboratory experiments were performed to study the change in irradiance induced production of Fe(II) in seawater in the presence of two open oceanic Southern Ocean diatom species, Thalassiosira sp. and Chaetoceros brevis. Three irradiance conditions were applied: 1) UVB + UVA + VIS, 2) UVA + VIS, and 3) VIS, and Fe concentrations of 0 and 5 nM Fe were added to natural Southern Ocean seawater (containing 0.32 nM dissolved Fe and 1.69 equivalents of nM L − 1 Fe dissolved organic ligands, log K′ = 22.03). The photoproduced concentration of Fe(II) showed no relationship with the concentration of total dissolved Fe or the concentration of strongly chelated iron. During incubations with the diatoms an increase in the Fe(II) concentration during the second day suggested a modification of the Fe speciation. In the presence of Thalassiosira sp. photoreduction of Fe(III) was observed, whereas in the presence of C. brevis irradiance independent Fe(III) reduction played an important role in the Fe(II) production. Furthermore, a decrease in the strongly chelated Fe concentration, in concert with a decrease in the conditional stability constant, suggested a modification of the strongly chelated Fe fraction in the experiments with C. brevis. The chelated Fe fraction did not change in cultures with Thalassiosira sp. Overall, the presence of diatoms appeared to enhance the reactive Fe pool improving the biological availability of Fe.
Effect of Nutrients on Diatom Growth: A Review
Trends in Sciences, 2022
Diatoms are one of the unicellular algae with a rare presence of unaltered, durable, transparent and species-specific silica frustules that persist even after cell death in the deposits of water bodies. Diatom has high capacity for absorption of metals for maintaining the water quality and high rate of multiplication. These characters promoted the use of this microbial biomass for effluent detoxification. These diatoms can also solve metal toxicity problems in aquatic ecosystems in the water polluted environment. In the present review, the focus is on several nutrients (nitrogen, phosphorus, iron and silica) that are essential for the growth of diatoms at very low concentrations, but most of them are toxic at high concentrations. It also shows the relationship between heavy metal stress and lipid body induction which may be a valuable indicator for the evaluation of heavy metal contamination of fluvial ecosystems. HIGHLIGHTS Diatoms are eukaryotic, unicellular, photosynthetic, silic...
Plant Physiology, 1997
Flavodoxin is a small electron-transfer protein capable of replacing ferredoxin during periods of Fe deficiency. When evaluating the suitability of flavodoxin as a diagnostic indicator for Fe limitation of phytoplankton growth, we examined its expression in two marine diatoms we cultured using trace-metal-buffered medium. Thalassio-sira weissflogii and Phaeodactylum tricornutum were cultured in ethylenediaminetetraacetic acid-buffered Sargasso Sea water containing from 10 to 1000 nM added Fe. Trace-metal-buffered cultures of each diatom maintained high growth rates across the entire range of Fe additions. Similarly, declines in chlorophyll/cell and in the ratio of photosystem II variable-to-maximum fluorescence were negligible (P. tricornutum) to moderate (T. weissflogii; 54% decline in chlorophyll/cell and 22% decrease in variable-to-maximum fluorescence). Moreover, only minor variations in photosynthetic parameters were observed across the range of additions. In contrast, flavodox...
2013
ABSTRACT In 50%of the ocean, iron (Fe) limits phytoplankton growth, including that of the diatomPseudo-nitzschia. Fe-limitedPseudo-nitzschiaspp. may produce the potent neurotoxin domoic acid (DA) to access Cu, needed at the core of a high-affinity Fe transport system. To test this hypothesis, we investigated the growth, physiology, and DA production of P. delicatissima under Fe limitations, Cu starvation, and Fe and Cu co-limitations. Compared with the control, Fe limitation decreased chlorophyll content by up to 86% and quantum yield (QY) by 3.6-fold. Severe Fe limitation decreased esterase activity by 60%and maintained lipid content, while mild Fe limitation increased both esterase activity and lipid content by 23% and 100%, respectively. Cu starvation increased chlorophyll content, lipid content, and esterase activity by 76%, 303%, and 47%, respectively, with QY being identical to replete cells. Co-limitations induced modifications close to, but significantly different from, Fe limitations. P. delicatissima produced no DA during these experiments. In this species, the Cu demand for Fe acquisition may be low relative to other cellular Cu pools or this species may not use Cu to uptake Fe.