Inorganic carbon acquisition by the chrysophyte alga Mallomonas papillosa

2005 ◽  
Vol 83 (7) ◽  
pp. 891-897 ◽  
Author(s):  
Shabana Bhatti ◽  
Brian Colman
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Photosynthetic Oxygen Evolution ◽  
Intracellular Accumulation ◽  
Oxygen Evolution Rate ◽  
Internal Ph ◽  
Bicarbonate Uptake ◽  
Photosynthetic Oxygen ◽  
Ph Range ◽  
External Ph

Photosynthetic characteristics of the chrysophyte alga Mallomonas papillosa Harris et Bradley were investigated to determine whether this species has some form of CO2-concentrating mechanism. The effect of external pH on the photosynthetic oxygen evolution rate of air-grown cells demonstrated an optimum in the pH range 5.0–7.0. This species lacked external carbonic anhydrase, and the cells had no capacity for direct bicarbonate uptake and had a low affinity for dissolved inorganic carbon. Measurement of the fluxes of CO2 and O2 in photosynthesizing cells at pH 7.0, using mass spectrometry, displayed no rapid uptake but only a slow depletion of CO2 from the medium upon illumination. Furthermore, CO2 uptake and O2 evolution by M. papillosa was greatly reduced by iodoacetamide, an inhibitor of CO2 fixation. The overall internal pH of M. papillosa was determined by distribution of 14C-benzoic acid over the pH range 5.5–6.0 and [2-14C]-5,5-dimethyloxazolidine-2,4-dione over the pH range 6.5–7.0 between the cells and medium. As the external pH was lowered from 7.0 to 5.5, there was a decrease in the internal pH of M. papillosa cells from 8.31 to 7.75. The ΔpH was great enough to allow the intracellular accumulation of inorganic carbon by the diffusive uptake of CO2.Key words: bicarbonate uptake, chrysophyte, CO2 uptake, internal pH, Mallomonas papillosa.

Mechanisms of inorganic carbon acquisition in two Euglena species

2005 ◽  
Vol 83 (7) ◽  
pp. 865-871 ◽  
Author(s):  
Brian Colman ◽  
Konstantine D Balkos
Keyword(s):  
Euglena Gracilis ◽  
Inorganic Carbon ◽  
Bicarbonate Transport ◽  
Alkaline Ph ◽  
Internal Ph ◽  
Bicarbonate Uptake ◽  
Acid Tolerant ◽  
Euglena Mutabilis ◽  
Ph Range ◽  
External Ph

The mechanism of inorganic carbon uptake was examined in Euglena gracilis Klebs. and the acidophilic species Euglena mutabilis Schmitz. Both species, whether grown in acidic (pH 3.5) or alkaline (pH 7.5) media lack external carbonic anhydrase. Acid-grown E. gracilis was shown to have no capacity for bicarbonate transport, but transport was induced on transfer to alkaline medium (pH 7.5) in the light over a period of 8 h. In contrast, acid-grown E. mutabilis appears to have no capacity for bicarbonate transport even at neutral pH. The overall internal pH of the cells was determined by equilibration with 14C-labelled benzoic acid over the pH range 3.5–5.0 and with 14C-labelled 5,5-dimethyloxazolidine-2,4-dione over the range pH 5.5–7.5. The acidophilic species maintains an internal pH range of 6.6–6.8 in an external pH range of 3.5–5.5, whereas the acid-tolerant species E. gracilis maintains a neutral internal pH in an external pH range of 3.5–7.5. Measurement, by mass spectrometry, of the fluxes of CO2 and O2 in photosynthesizing cells at pH 3.5 demonstrated a rapid uptake of CO2 by both species that was completely blocked by iodoacetamide, an inhibitor of CO2 fixation. Uptake of CO2 by E. gracilis, grown at pH 7.5, was not completely inhibited by iodoacetamide and O2 evolution was sustained when the cells reached the CO2 compensation concentration, indicating a direct uptake of bicarbonate. These data indicate that the acidophilic species, E. mutabilis, takes up CO2 by diffusion, whereas the acid-tolerant species, E. gracilis, takes up CO2 by diffusion at acid pH levels but has some capacity for active bicarbonate uptake when grown at alkaline pH levels.Key words: acidophilic alga, acidotolerant alga, bicarbonate uptake, CO2 uptake, Euglena gracilis, Euglena mutabilis, internal pH.

Photosynthetic Characteristics of Three Strains of Cyanobacteria Grown under Low-or High-C02 Conditions

1996 ◽  
Vol 51 (1-2) ◽  
pp. 40-46 ◽  
Author(s):  
Shigetoh Miyachi ◽  
Joachim Bürger ◽  
Kiriakos Kotzabasis ◽  
Jens Thielmann ◽  
Horst Senger
Keyword(s):  
Oxygen Evolution ◽  
Dissolved Inorganic Carbon ◽  
Electron Flow ◽  
Liquid Nitrogen Temperature ◽  
Fluorescence Induction ◽  
Anabaena Variabilis ◽  
Photosynthetic Oxygen Evolution ◽  
Induction Kinetics ◽  
Fluorescence Induction Kinetics ◽  
Photosynthetic Oxygen

Abstract Quantum requirements of photosynthetic oxygen evolution at 679 nm, fluorescence emis­sion spectra at liquid nitrogen temperature (77 K) and fluorescence induction kinetics in the presence of DCM U, were measured in the cyanobacteria Anabaena variabilis M3, Anabaena variabilis ATCC 29413 and A nacystis nidulans R2, each grown under low-or high-CO2 conditions. Low -CO2 grown cells of the cyanobacteria showed a higher quantum requirement of photosynthetic oxygen evolution and a higher ratio o F710-740 to F680-700 fluorescence and a lower variable fluorescence in the presence of DCMU than high-CO2 grown cells. These findings indicate a change in excitation energy distribution in favour of photosystem I. The result might be an enhancement in ATP formation caused by cyclic electron flow which in turn provokes dissolved inorganic carbon (DIC) accumulation in these low-CO2 grown cells.

Growth, photosynthesis, and extracellular organic release in colonized and axenic Myriophyllum spicatum

1989 ◽  
Vol 67 (12) ◽  
pp. 3429-3438 ◽  
Author(s):  
H. Godmaire ◽  
C. Nalewajko
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Myriophyllum Spicatum ◽  
Distribution Patterns ◽  
Release Rates ◽  
Lower Growth ◽  
Bicarbonate Uptake ◽  
Algal Photosynthesis ◽  
Major Nutrients ◽  
Carbon Concentrations

Growth and photosynthesis of axenic and colonized Myriophyllum were compared to test the validity of using axenic plants as controls in the quantification of extracellular organic carbon (EOC) release. Axenic plants were characterized by lower growth rates that could be attributed to the unavailability of some major nutrients other than N, P, or C and (or) micronutrients in the culture medium. Vmax, the maximum rate of bicarbonate uptake, and Pmax, the maximum light-saturated rate of photosynthesis, of nonaxenic Myriophyllum were significantly higher than those of axenic plants. These differences could be attributed to epiphytic algal photosynthesis. At subsaturating dissolved inorganic carbon concentrations (below 15 mg C ∙ L−1), both plants achieved similar rates of photosynthesis but differed in the kinetics of EOC release. In short-term incubation (2–6 h), 14C-EOC accounted for 0.2–0.4% of photosynthesis, and total EOC amounted to 1.3–3.8%. 14C-EOC consisted primarily (≥ 60%) of low molecular weight products (≤ 1500). No differences were apparent in size distribution patterns of 14C-EOC from axenic and nonaxenic Myriophyllum and at different dissolved inorganic carbon concentrations. Axenic plants generally showed lower rates of EOC release (in absolute values). On colonized Myriophyllum, the contribution of the epiphytes to the EOC release pool was found to be low (≤ 20% of 14C-EOC) and could partly explain the greater EOC release rates of nonaxenic plants. However, our results are not totally conclusive because the lower growth rate of axenic plants could also be responsible for the lower photosynthetic and EOC release rates of these plants.

Proton-sulfate cotransport: external proton activation of sulfate influx into human red blood cells

1984 ◽  
Vol 247 (3) ◽  
pp. C247-C259 ◽  
Author(s):  
M. A. Milanick ◽  
R. B. Gunn
Keyword(s):  
Membrane Potential ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Half Cycle ◽  
Ph Values ◽  
Human Red Blood Cells ◽  
Internal Ph ◽  
Ph Range ◽  
External Ph ◽  
Chloride Concentrations

Sulfate influx into human red blood cells was measured at 0 and 22 degrees C at several fixed external pH values between 3 and 10. These cells had normal internal pH and chloride concentrations so that sulfate influx was not limited by the efflux half-cycle reactions. The flux was a Michaelis-Menten function of sulfate concentration at each pH with K1/2SO4 = 4-10 mM. External protons activated influx 100-fold at a single site with a pK = 5.9 at 22 degrees C and 5.5 at 0 degrees C. This pK is similar to the value 5.99 +/- 0.3 for external proton binding to the sulfate-loaded transporter at 0 degrees C (J. Gen. Physiol. 79: 87-114, 1982). The flux was stilbene sensitive even in valinomycin-treated cells and was independent of membrane potential. This proton-activated influx appears to be proton-sulfate cotransport. At high pH there was a proton-independent flux that was membrane potential and stilbene sensitive. This proton-insensitive flux appears to be SO4(2-)/Cl- exchange or net sulfate influx. The sulfate influx over the entire pH range may be described in terms of an equation for the sum of the influxes through these two pathways on band 3.

Inorganic carbon acquisition by Chlamydomonas acidophila across a pH range

2005 ◽  
Vol 83 (7) ◽  
pp. 872-878 ◽  
Author(s):  
Elly Spijkerman
Keyword(s):  
Growth Rate ◽  
Carbonic Anhydrase ◽  
Inorganic Carbon ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Chlamydomonas Acidophila ◽  
Ph Conditions ◽  
Ph Range ◽  
Very High ◽  
External Ph

Chlamydomonas acidophila Negoro had a higher maximum growth rate upon aeration with 5% CO2 (v/v) than in nonaerated conditions at an external pH above 2. In medium with a pH of 1.0 or 2.0, a decrease in the maximum growth rate was observed upon CO2 aeration in comparison with nonaerated conditions. At both very low and very high external pH conditions, an induction of external carbonic anhydrase was detected; this being more pronounced in CO2-aerated cells than in nonaerated cells. It is therefore suggested that the induction of carbonic anhydrase is part of a stress response in Chlamydomonas acidophila. Comparison of some physiological characteristics of Chlamydomonas acidophila acclimated at pH 2.65 and at pH 6.0, revealed that CO2 aeration increased gross maximum photosynthesis at both pHs, whereas respiration, light acclimation, and photoinhibition were not effected. At pH 2.65, Chlamydomonas acidophila was found to have a carbon-concentrating mechanism under nonaerated conditions, whereas it did not under CO2-aerated conditions at pH 6. The affinity for CO2 use in O2 production was not dependent on CO2 aeration, but it was much lower at pH 6 than it was at pH 2.65. CO2 kinetic characteristics indicate that the photosynthesis of Chlamydomonas acidophila in its natural environment is not limited by inorganic carbon.Key words: Chlamydomonas acidophila, CCM, external carbonic anhydrase, photosynthesis, growth rates, pH stress, CO2.

scholarly journals Cyanobacterial carbon concentrating mechanisms facilitate sustained CO<sub>2</sub> depletion in eutrophic lakes

2017 ◽  
Vol 14 (11) ◽  
pp. 2865-2875 ◽  
Author(s):  
Ana M. Morales-Williams ◽  
Alan D. Wanamaker Jr. ◽  
John A. Downing
Keyword(s):  
Inorganic Carbon ◽  
Phytoplankton Bloom ◽  
Dissolved Inorganic Carbon ◽  
Negative Relationship ◽  
Anthropogenic Pressure ◽  
Phytoplankton Blooms ◽  
Eutrophic Lakes ◽  
Bicarbonate Uptake ◽  
Carbon Concentrating Mechanisms ◽  
Photosynthetic Fractionation

Abstract. Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3−) across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs). To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC) and phytoplankton particulate organic carbon (δ13Cphyto) in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass–balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3− during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3− uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

scholarly journals Diversity and Mechanisms of Alkali Tolerance in Lactobacilli

2007 ◽  
Vol 73 (12) ◽  
pp. 3909-3915 ◽  
Author(s):  
Yuki Sawatari ◽  
Atsushi Yokota
Keyword(s):  
Plant Material ◽  
Lactobacillus Casei ◽  
Glucose Utilization ◽  
Ph Values ◽  
Internal Ph ◽  
Alkali Tolerance ◽  
Ph Range ◽  
High Alkali ◽  
External Ph

ABSTRACT We determined the maximum pH that allows growth (pHmax) for 34 strains of lactobacilli. High alkali tolerance was exhibited by strains of Lactobacillus casei, L. paracasei subsp. tolerans, L. paracasei subsp. paracasei, L. curvatus, L. pentosus, and L. plantarum that originated from plant material, with pHmax values between 8.5 and 8.9. Among these, L. casei NRIC 1917 and L. paracasei subsp. tolerans NRIC 1940 showed the highest pHmax, at 8.9. Digestive tract isolates of L. gasseri, L. johnsonii, L. reuteri, L. salivarius subsp. salicinius, and L. salivarius subsp. salivarius exhibited moderate alkali tolerance, with pHmax values between 8.1 and 8.5. Dairy isolates of L. delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, and L. helveticus exhibited no alkali tolerance, with pHmax values between 6.7 and 7.1. Measurement of the internal pH of representative strains revealed the formation of transmembrane proton gradients (ΔpH) in a reversed direction (i.e., acidic interior) at alkaline external-pH ranges, regardless of their degrees of alkali tolerance. Thus, the reversed ΔpH did not determine alkali tolerance diversity. However, the ΔpH contributed to alkali tolerance, as the pHmax values of several strains decreased with the addition of nigericin, which dissipates ΔpH. Although neutral external-pH values resulted in the highest glycolysis activity in the presence of nigericin regardless of alkali tolerance, substantial glucose utilization was still detected in the alkali-tolerant strains, even in a pH range of between 8.0 and 8.5, at which the remaining strains lost most activity. Therefore, the alkali tolerance of glycolysis reactions contributes greatly to the determination of alkali tolerance diversity.

Comparative study of dissolved inorganic carbon utilization and photosynthetic responses in Nannochloris (Chlorophyceae) and Nannochloropsis (Eustigmatophyceae) species

1998 ◽  
Vol 76 (6) ◽  
pp. 1104-1108 ◽  
Author(s):  
I Emma Huertas ◽  
Luis M Lubián
Keyword(s):  
Life Cycle ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Nannochloropsis Oculata ◽  
Marine Phytoplankton ◽  
Bicarbonate Transport ◽  
Photosynthetic Oxygen Evolution ◽  
Carbon Utilization ◽  
Nannochloropsis Gaditana ◽  
Inorganic Carbon Utilization

Four species of marine microalgae with similar morphology and life cycle, namely Nannochloris atomus Butcher, Nannochloris maculata Butcher, Nannochloropsis gaditana Lubian, and Nannochloropsis oculata (Droop) Hibberd, have been examined with respect to their affinity for different sources of dissolved inorganic carbon. External carbonic anhydrase activity was not found in any of these species, but the cell affinity for dissolved inorganic carbon (DIC) in Nannochloris species was affected by the inhibitor acetazolamide at a concentration of 400 µM. Measurement of photosynthetic rates and CO2 compensation points at different pH values showed that the Nannochloris species had a greater capacity for CO2 rather than HCO3- utilization. In contrast, the observed rates of photosynthetic oxygen evolution in Nannochloropsis species were greater than could be accounted for by the theoretical rate of CO2 supply from the spontaneous dehydration of bicarbonate in the external medium. This indicates that these algae were able to transport bicarbonate across the plasmalemma. Furthermore, the K0.5 (DIC) value at acidic pH showed that Nannochloropsis oculata could also use CO2 as an exogenous carbon source for photosynthesis. Although the species of marine phytoplankton used in this study possess similar morphological characteristics and life cycle, there exist many differences in the mode of inorganic carbon utilization between these microalgae.Key words: Nannochloris, Nannochloropsis, inorganic carbon utilization, bicarbonate transport, CO2 compensation point, photosynthesis.

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