scholarly journals RETRACTED ARTICLE: Increased biomass productivity in green algae by tuning non-photochemical quenching

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Silvia Berteotti ◽  
Matteo Ballottari ◽  
Roberto Bassi
Keyword(s):  
Heat Dissipation ◽  
Biomass Productivity ◽  
Growth Conditions ◽  
Complex Stress ◽  
Biofuel Production ◽  
Photochemical Quenching ◽  
Protein Accumulation ◽  
Potential Productivity ◽  
Wide Range ◽  
Non Photochemical Quenching

Abstract Photosynthetic microalgae have a high potential for the production of biofuels and highly valued metabolites. However, their current industrial exploitation is limited by a productivity in photobioreactors that is low compared to potential productivity. The high cell density and pigment content of the surface layers of photosynthetic microalgae result in absorption of excess photons and energy dissipation through non-photochemical quenching (NPQ). NPQ prevents photoinhibition, but its activation reduces the efficiency of photosynthetic energy conversion. In Chlamydomonas reinhardtii, NPQ is catalyzed by protein subunits encoded by three lhcsr (light harvesting complex stress related) genes. Here, we show that heat dissipation and biomass productivity depends on LHCSR protein accumulation. Indeed, algal strains lacking two lhcsr genes can grow in a wide range of light growth conditions without suffering from photoinhibition and are more productive than wild-type. Thus, the down-regulation of NPQ appears to be a suitable strategy for improving light use efficiency for biomass and biofuel production in microalgae.

scholarly journals Assessment of Chlorella vulgaris, Scenedesmus obliquus, and Oocystis minuta for removal of sulfate, nitrate, and phosphate in wastewater

2020 ◽  
Vol 11 (3) ◽  
pp. 311-326 ◽  
Author(s):  
Sheriff Olalekan Ajala ◽  
Matthew L. Alexander
Keyword(s):  
Chlorella Vulgaris ◽  
Scenedesmus Obliquus ◽  
Biomass Productivity ◽  
Growth Conditions ◽  
Phosphate Removal ◽  
Biofuel Production ◽  
Protein Accumulation ◽  
Contaminant Removal ◽  
Biochemical Component ◽  
Sulfate Removal

AbstractApplication of wastewater for algal biomass production can not only lead to production of thousands of tons of biomass for subsequent biofuel production, but also can provide for significant removal of contaminants in wastewater. The aim of the present study is to evaluate the growth, contaminant removal, and biochemical component (lipid, carbohydrate, and protein) accumulation potential of Chlorella vulgaris, Scenedesmus obliquus, and Oocystis minuta cells in wastewater supplemented with different concentrations of sulfate, nitrate, and phosphate. The results show maximum biomass productivity of 33, 19, and 98 mg dw/L/d for C. vulgaris, S. obliquus, and O. minuta, respectively. Phosphate removal (more than 90%) was highest in the culture with O. minuta; about 93% nitrate was removed by C. vulgaris, and the highest sulfate removal of 36% was observed in the culture with S. obliquus. The biochemical composition of the microalgae cells is in the ranges of 22–65% carbohydrate, 19–38% protein, and 8–17% lipid. This indicates that carbohydrate and protein are preferentially accumulated as compared to lipids under the growth conditions investigated for each of the microalgae strains.

scholarly journals Chilling tolerance in Zizania latifólia

2016 ◽  
Vol 34 (1) ◽  
pp. 39-45
Author(s):  
Zihong Ye ◽  
Haifeng Cui ◽  
Xinxin An ◽  
Xiaoping Yu
Keyword(s):  
Cold Stress ◽  
Heat Dissipation ◽  
Chilling Tolerance ◽  
Photochemical Quenching ◽  
Electric Transport ◽  
Zizania Latifolia ◽  
Critical Pathways ◽  
Photosynthesis Inhibition ◽  
Non Photochemical Quenching ◽  
Latent Activity

ABSTRACT: The tumescent stems of Zizania latifolia are consumed as vegetable in southern and eastern Asia. This study aimed to compare photosynthesis and chilling tolerance parameters between two well-known Zizania latifolia cultivars: Longjiao 2 and Zhejiao 911, which are chilling tolerant and sensitive, respectively. We found that severe cold stress induced photosynthesis inhibition (5°C) resulted from non-stomatal factors. However, net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of the cultivar Longjiao 2 were higher than that of Zhejiao 911 with more gradual variations. Six parameters of chlorophyll fluorescence including latent activity of PSII (Fv/F0), efficiency of primary photochemistry (Fv/Fm), photochemical quenching coefficient (qP), non-photochemical quenching coefficient (qN), quantum yield of electric transport (Yield) and the ratio of electric transport at PSII (ETR) were analyzed in the two cultivars. We found that Longjiao 2 had significantly higher Fv/Fm and qN than Zhejiao 911 while qP values were only slightly different for the two lines at severe cold stress. In our experiments, Yield and ETR changed in a similar way in both Longjiao 2 and Zhejiao 911. In addition, the ability of heat dissipation of Longjiao 2 was statistically higher than that found in Zhejiao 911 when treated at 5°C for one day. These data suggest that cultivar Longjiao 2 induces chilling tolerance by modulating critical pathways including photosynthesis and energy dissipation.

scholarly journals Identification of parallel pH- and zeaxanthin-dependent quenching of excess energy in LHCSR3 in Chlamydomonas reinhardtii

2020 ◽  
Author(s):  
Julianne M. Troiano ◽  
Federico Perozeni ◽  
Raymundo Moya ◽  
Luca Zuliani ◽  
Kwangryul Baek ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Light Harvesting ◽  
Complex Stress ◽  
Excess Energy ◽  
Photochemical Quenching ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Non Photochemical Quenching

AbstractUnder high light conditions, oxygenic photosynthetic organisms avoid photodamage by thermally dissipating excess absorbed energy, which is called non-photochemical quenching (NPQ). In green algae, a chlorophyll and carotenoid-binding protein, light-harvesting complex stress-related (LHCSR3), detects excess energy via pH and serves as a quenching site. However, the mechanisms by which LHCSR3 functions have not been determined. Using a combined in vivo and in vitro approach, we identify two parallel yet distinct quenching processes, individually controlled by pH and carotenoid composition, and their likely molecular origin within LHCSR3 from Chlamydomonas reinhardtii. The pH-controlled quenching is removed within a mutant LHCSR3 that lacks the protonable residues responsible for sensing pH. Constitutive quenching in zeaxanthin-enriched systems demonstrates zeaxanthin-controlled quenching, which may be shared with other light-harvesting complexes. We show that both quenching processes prevent the formation of damaging reactive oxygen species, and thus provide distinct timescales and mechanisms of protection in a changing environment.

scholarly journals Ascorbate deficiency does not limit non-photochemical quenching in Chlamydomonas reinhardtii

2019 ◽  
Author(s):  
André Vidal-Meireles ◽  
Dávid Tóth ◽  
László Kovács ◽  
Juliane Neupert ◽  
Szilvia Z. Tóth
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Vascular Plants ◽  
Regulation Of Gene Expression ◽  
Growth Conditions ◽  
Photochemical Quenching ◽  
Wild Type ◽  
Knockout Mutant ◽  
Dependent Component ◽  
Non Photochemical Quenching ◽  
Energy Dependent

SummaryAscorbate (vitamin C) plays essential roles in development, signaling, hormone biosynthesis, regulation of gene expression, stress resistance and photoprotection. In vascular plants, violaxanthin de-epoxidase (VDE) requires ascorbate (Asc) as reductant, thereby it is required for the energy-dependent component of non-photochemical quenching (NPQ). In order to assess the role of Asc in NPQ in green algae, which are known to contain low amounts of Asc, we searched for an insertional Chlamydomonas reinhardtii mutant affected in the VTC2 gene, essential for Asc biosynthesis. The Crvtc2-1 knockout mutant was viable and, depending on the growth conditions, it contained 10 to 20% Asc relative to its wild type. When Chlamydomonas was grown photomixotrophically at moderate light, the zeaxanthin-dependent component of NPQ emerged upon strong red illumination both in the Crvtc2-1 mutant and in its wild type. Deepoxidation was unaffected by Asc deficiency, demonstrating that the Chlorophycean VDE found in Chlamydomonas does not require Asc as a reductant. The rapidly induced, energy-dependent NPQ component, characteristic of photoautotrophic Chlamydomonas cultures grown at high light, was not limited by Asc deficiency either. On the other hand, a reactive oxygen species-induced photoinhibitory NPQ component was greatly enhanced upon Asc deficiency, both under photomixotrophic and photoautotrophic conditions. These results demonstrate that Asc has distinct roles in NPQ formation in Chlamydomonas than in vascular plants.One-sentence summaryIn Chlamydomonas -in contrast to seed plants-, ascorbate is not required for violaxanthin deepoxidation and energy-dependent non-photochemical quenching but it mitigates photoinhibitory quenching.

scholarly journals Agave By-Products: An Overview of Their Nutraceutical Value, Current Applications, and Processing Methods

2021 ◽  
Vol 2 (3) ◽  
pp. 720-743
Author(s):  
Jimena Álvarez-Chávez ◽  
Mar Villamiel ◽  
Liliana Santos-Zea ◽  
Aurea K. Ramírez-Jiménez
Keyword(s):  
Enzymatic Saccharification ◽  
Biomass Productivity ◽  
Industrial Applications ◽  
Biofuel Production ◽  
Alcoholic Beverages ◽  
Processing Methods ◽  
Wide Range ◽  
Simple Carbohydrates ◽  
Chemical Pretreatments ◽  
By Products

Agave, commonly known as “maguey” is an important part of the Mexican tradition and economy, and is mainly used for the production of alcoholic beverages, such as tequila. Industrial exploitation generates by-products, including leaves, bagasse, and fibers, that can be re-valorized. Agave is composed of cellulose, hemicellulose, lignin, fructans, and pectin, as well as simple carbohydrates. Regarding functional properties, fructans content makes agave a potential source of prebiotics with the capability to lower blood glucose and enhance lipid homeostasis when it is incorporated as a prebiotic ingredient in cookies and granola bars. Agave also has phytochemicals, such as saponins and flavonoids, conferring anti-inflammatory, antioxidant, antimicrobial, and anticancer properties, among other benefits. Agave fibers are used for polymer-based composite reinforcement and elaboration, due to their thermo-mechanical properties. Agave bagasse is considered a promising biofuel feedstock, attributed to its high-water efficiency and biomass productivity, as well as its high carbohydrate content. The optimization of physical and chemical pretreatments, enzymatic saccharification and fermentation are key for biofuel production. Emerging technologies, such as ultrasound, can provide an alternative to current pretreatment processes. In conclusion, agaves are a rich source of by-products with a wide range of potential industrial applications, therefore novel processing methods are being explored for a sustainable re-valorization of these residues.

scholarly journals Photoprotection by carotenoids of Plantago media photosynthetic apparatus in natural conditions.

2012 ◽  
Vol 59 (1) ◽  
Author(s):  
Tamara Golovko ◽  
Olga Dymova ◽  
Ilya Zakhozhiy ◽  
Igor Dalke ◽  
Galina Tabalenkova
Keyword(s):  
Heat Dissipation ◽  
Photosynthetic Apparatus ◽  
Photochemical Quenching ◽  
Total Pool ◽  
Plantago Media ◽  
Non Photochemical Quenching ◽  
Sun Leaves ◽  
Daily Changes ◽  
Shade Plants

The study of daily changes in photosynthetic rate, of energy used in photochemical and non-photochemical processes, and of carotenoid composition aimed at evaluating the role of xanthophyll cycle (XC) in protection of hoary plantain plants (Plantago media) in nature. The leaves of sun plants differed from shade plants in terms of CO(2) exchange rate and photosynthetic pigments content. The total pool XC pigments and the conversion state increased from morning to midday in sun plants. An increase in zeaxanthin content occurred concomitantly with the violaxanthin decrease. About 80% violaxanthin was involved in conversion. The maximum of zeaxanthin in XC pigments pool was 60%. The conversion state of XC was twice as lower in shade plants than that in sun plants. The photosynthesis of sun leaves was depressed strongly at midday, but changes of maximum quantum yield of PS2 (F(v)/F(m)) were not apparent at that time. The coefficient qN (non-photochemical quenching) in the sun leaves changed strongly, from 0.3 to 0.9 as irradiance increased. The direct relation between heat dissipation and the conversion state of XC in plantain leaves was revealed. Thus, plantain leaves were found to be resistant to excess solar radiation due to activation of qN mechanisms associated with the XC de-epoxidation.

scholarly journals Combined chlorophyll fluorescence techniques to study environmental impact on the mountain moss Polytrichum commune

2021 ◽  
Vol 11 (1) ◽  
pp. 161-173
Author(s):  
Gabriella Nora Maria Giudici
Keyword(s):  
Chlorophyll Fluorescence ◽  
Conformational Changes ◽  
Heat Dissipation ◽  
Fluorescence Induction ◽  
High Light ◽  
Chlorophyll Fluorescence Induction ◽  
Photochemical Quenching ◽  
Light Harvesting Complexes ◽  
Polytrichum Commune ◽  
Non Photochemical Quenching

Two chlorophyll fluorescence (ChlF) methods were used to study the effects of high light (photoinhibition) and dehydration, common stressors of the alpine environment, on primary photosynthetic processes in the moss Polytrichum commune from the Czech Republic, the Jeseníky Mountains. Photoinhibition (PI) was studied in fully hydrated thalli of P. commune and during the period of spontaneous desiccation. Time courses of Kautsky kinetics (KK) of ChlF and derived parameters: maximum quantum yield (FV/FM), effective quantum yeld (ΦPSII), and non-photochemical quenching parameters, were measured before and after the samples were treated with high light (1500 µmol m-2 s-1 PAR) for 60 min. Dehydration effects were tested in two sets of experiments with a Pulse-Amplitude-Modulation fluorometry (PAM) and Fast Chlorophyll Fluorescence induction curve (OJIP) techniques. In PAM tests, the desiccating samples were exposed to saturating light pulses every 10 min. in order to obtain ΦPSII and non-photochemical quenching (NPQ). In the second dehydration experiment, OJIP transients of ChlF were repeatedly recorded, OJIP-derived ChlF parameters were plotted against relative water content (RWC) monitored during desiccation. Combined ChF techniques provided insights into the mechanisms activated during P. commune desiccation, such as dissipation of excess absorbed energy through heat dissipation, and conformational changes or destructions of the light harvesting complexes. Combination of stressors resulted in amplified interference with the photosynthetic machinery, even when the added stressor (dehydration) was applied in low dose.

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