The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Josephine Z Rapp - One of the best experts on this subject based on the ideXlab platform.
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microbial ecology of the cryosphere sea ice and glacial habitats
Nature Reviews Microbiology, 2015Co-Authors: Antje Boetius, Alexandre M Anesio, Jody W Deming, Jill A Mikucki, Josephine Z RappAbstract:The Earth's cryosphere comprises those regions that are cold enough for water to turn into ice. Recent findings show that the icy realms of polar oceans, glaciers and ice sheets are inhabited by microorganisms of all three domains of life, and that temperatures below 0 °C are an integral force in the diversification of microbial life. Cold-adapted microorganisms maintain key ecological functions in icy habitats: where sunlight penetrates the ice, Photoautotrophy is the basis for complex food webs, whereas in dark subglacial habitats, chemoautotrophy reigns. This Review summarizes current knowledge of the microbial ecology of frozen waters, including the diversity of niches, the composition of microbial communities at these sites and their biogeochemical activities.
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microbial ecology of the cryosphere sea ice and glacial habitats
Nature Reviews Microbiology, 2015Co-Authors: Antje Boetius, Alexandre M Anesio, Jody W Deming, Jill A Mikucki, Josephine Z RappAbstract:In this Review, Boetiuset al. summarize our current knowledge of the microbial ecology of Earth's frozen realms, including sea ice and glacial habitats. They describe the diversity of niches, the composition of microbial communities at these sites and their biogeochemical activities. The Earth's cryosphere comprises those regions that are cold enough for water to turn into ice. Recent findings show that the icy realms of polar oceans, glaciers and ice sheets are inhabited by microorganisms of all three domains of life, and that temperatures below 0 °C are an integral force in the diversification of microbial life. Cold-adapted microorganisms maintain key ecological functions in icy habitats: where sunlight penetrates the ice, Photoautotrophy is the basis for complex food webs, whereas in dark subglacial habitats, chemoautotrophy reigns. This Review summarizes current knowledge of the microbial ecology of frozen waters, including the diversity of niches, the composition of microbial communities at these sites and their biogeochemical activities.
Terry M Bricker - One of the best experts on this subject based on the ideXlab platform.
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the psbp protein is required for photosystem ii complex assembly stability and Photoautotrophy in arabidopsis thaliana
Journal of Biological Chemistry, 2007Co-Authors: Stefan R Hargett, Laurie K Frankel, Haijun Liu, Terry M BrickerAbstract:Interfering RNA was used to suppress the expression of the genes At1g06680 and At2g30790 in Arabidopsis thaliana, which encode the PsbP-1 and PsbP-2 proteins, respectively, of photosystem II (PS II). A phenotypic series of transgenic plants was recovered that expressed intermediate and low amounts of PsbP. Chlorophyll fluorescence induction and QA– decay kinetics analyses were performed. Decreasing amounts of expressed PsbP protein led to the progressive loss of variable fluorescence and a marked decrease in the fluorescence quantum yield (FV/FM). This was primarily due to the loss of the J to I transition. Analysis of the fast fluorescence rise kinetics indicated no significant change in the number of PS IIβ centers present in the mutants. Analysis of QA– decay kinetics in the absence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea indicated a defect in electron transfer from QA– to QB, whereas experiments performed in the presence of this herbicide indicated that charge recombination between QA– and the oxygen-evolving complex was seriously retarded in the plants that expressed low amounts of the PsbP protein. These results demonstrate that the amount of functional PS II reaction centers is compromised in the plants that exhibited intermediate and low amounts of the PsbP protein. Plants that lacked detectable PsbP were unable to survive in the absence of sucrose, indicating that the PsbP protein is required for Photoautotrophy. Immunological analysis of the PS II protein complement indicated that significant losses of the CP47 and D2 proteins, and intermediate losses of the CP43 and D1 proteins, occurred in the absence of the PsbP protein. This demonstrates that the extrinsic protein PsbP is required for PS II core assembly/stability.
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the psbq protein is required in arabidopsis for photosystem ii assembly stability and Photoautotrophy under low light conditions
Journal of Biological Chemistry, 2006Co-Authors: Stefan R Hargett, Laurie K Frankel, Terry M BrickerAbstract:RNA interference was used to simultaneously suppress the expression of the two genes that encode the PsbQ proteins of Photosystem II (PS II) in Arabidopsis thaliana, psbQ-1 (At4g21280) and psbQ-2 (At4g05180). Two independent PsbQ-deficient plant lines were examined. These plant lines produced little detectable PsbQ protein. Under normal growth light conditions, the wild type and mutant plants were visually indistinguishable. Additionally, analysis of steady state oxygen evolution rates and chlorophyll fluorescence characteristics indicated little alteration of photosynthetic capacity in the mutant plants. No loss of other PS II proteins was evident. Interestingly, flash oxygen yield analysis performed on thylakoid membranes isolated from the mutant and wild type plants indicated that the oxygen-evolving complex was quite unstable in the mutants. Furthermore, the lifetime of the S2 state of the oxygen-evolving complex appeared to be increased in these plants. Incubation of the wild type and mutant plants under low light growth conditions led to a significantly stronger observed phenotype in the mutants. The mutant plants progressively yellowed (after 2 weeks) and eventually died (after 3-4 weeks). The wild type plants exhibited only slight yellowing after 4 weeks under low light conditions. The mutant plants exhibited a large loss of a number of PS II components, including CP47 and the D2 protein, under low light conditions. Additionally, significant alterations of their fluorescence characteristics were observed, including an increased FO and decreased FV, yielding a large loss in PS II quantum efficiency (FV/FM). Analysis of QA decay kinetics in the absence of 3-(3,4-dichlorophenyl)-1,1-dimethyl urea indicated a defect in electron transfer from QA- to QB, whereas experiments performed in the presence of this herbicide indicated that the recombination rate between QA- and the S2 state was strongly retarded. These results indicate that the loss of the PsbQ protein induces significant changes in Photosystem II function, particularly in low light-grown plants, and that the PsbQ protein is required for photoautotrophic growth under low light conditions.
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the manganese stabilizing protein is required for photosystem ii assembly stability and Photoautotrophy in higher plants
Journal of Biological Chemistry, 2005Co-Authors: Myriam Mcchargue, Susan M Laborde, Laurie K Frankel, Terry M BrickerAbstract:Interfering RNA was used to suppress the expression of two genes that encode the manganese-stabilizing protein of photosystem II in Arabidopsis thaliana, MSP-1 (encoded by psbO-1, At5g66570), and MSP-2 (encoded by psbO-2, At3g50820). A phenotypic series of transgenic plants was recovered that expressed high, intermediate, and low amounts of these two manganese-stabilizing proteins. Chlorophyll fluorescence induction and decay analyses were performed. Decreasing amounts of expressed protein led to the progressive loss of variable fluorescence and a marked decrease in the fluorescence quantum yield (Fv/Fm) in both the absence and the presence of dichloromethylurea. This result indicated that the amount of functional photosystem II reaction centers was compromised in the plants that exhibited intermediate and low amounts of the manganese-stabilizing proteins. An analysis of the decay of the variable fluorescence in the presence of dichlorophenyldimethylurea indicated that charge recombination between Q A– and the S2 state of the oxygen-evolving complex was seriously retarded in the plants that expressed low amounts of the manganesestabilizing proteins. This may have indicated a stabilization of the S2 state in the absence of the extrinsic component. Immunological analysis of the photosystem II protein complement indicated that significant losses of the CP47, CP43, and D1 proteins occurred upon the loss of the manganese-stabilizing proteins. This indicated that these extrinsic proteins were required for photosystem II core assembly/stability. Additionally, although the quantity of the 24-kDa extrinsic protein was only modestly affected by the loss of the manganese-stabilizing proteins, the 17-kDa extrinsic protein dramatically decreased. The control proteins ribulose bisphosphate carboxylase and cytochrome f were not affected by the loss of the manganese-stabilizing proteins; the photosystem I PsaB protein, however, was significantly reduced in the low expressing transgenic plants. Finally, it was determined that the transgenic plants that expressed low amounts of the manganese-stabilizing proteins could not grow photoautotrophically.
Arpita Bose - One of the best experts on this subject based on the ideXlab platform.
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sustainable production of the biofuel n butanol by rhodopseudomonas palustris tie 1
bioRxiv, 2020Co-Authors: Wei Bai, Tahina Onina Ranaivoarisoa, Rajesh Singh, Karthikeyan Rengasamy, Arpita BoseAbstract:Anthropogenic carbon dioxide (CO2) release in the atmosphere from fossil fuel combustion has inspired scientists to study CO2 to fuel conversion. Oxygenic phototrophs such as cyanobacteria have been used to produce biofuels using CO2. However, oxygen generation during oxygenic photosynthesis affects biofuel production efficiency. To produce n-butanol (biofuel) from CO2, here we introduced an n-butanol biosynthesis pathway into an anoxygenic (non-oxygen evolving) photoautotroph, Rhodopseudomonas palustris TIE-1 (TIE-1). Using different carbon, nitrogen, and electron sources, we achieved n-butanol production in wild-type TIE-1 and mutants lacking electron-consuming (nitrogen-fixing) or acetyl-CoA-consuming (polyhydroxybutyrate and glycogen synthesis) pathways. The mutant lacking the nitrogen-fixing pathway produced highest n-butanol. Coupled with novel hybrid bioelectrochemical platforms, this mutant produced n-butanol using CO2, solar panel-generated electricity, and light, with high electrical energy conversion efficiency. Overall, this approach showcases TIE-1 as an attractive microbial chassis for carbon-neutral n-butanol bioproduction using sustainable, renewable, and abundant resources.
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towards sustainable bioplastic production using the photoautotrophic bacterium rhodopseudomonas palustris tie 1
Journal of Industrial Microbiology & Biotechnology, 2019Co-Authors: Tahina Onina Ranaivoarisoa, Rajesh Singh, Karthikeyan Rengasamy, Michael S Guzman, Arpita BoseAbstract:Bacterial synthesis of polyhydroxybutyrates (PHBs) is a potential approach for producing biodegradable plastics. This study assessed the ability of Rhodopseudomonas palustris TIE-1 to produce PHBs under various conditions. We focused on Photoautotrophy using a poised electrode (photoelectroautotrophy) or ferrous iron (photoferroautotrophy) as electron donors. Growth conditions were tested with either ammonium chloride or dinitrogen gas as the nitrogen source. Although TIE-1’s capacity to produce PHBs varied fairly under different conditions, photoelectroautotrophy and photoferroautotrophy showed the highest PHB electron yield and the highest specific PHB productivity, respectively. Gene expression analysis showed that there was no differential expression in PHB biosynthesis genes. This suggests that the variations in PHB accumulation might be post-transcriptionally regulated. This is the first study to systematically quantify the amount of PHB produced by a microbe via photoelectroautotrophy and photoferroautotrophy. This work could lead to sustainable bioproduction using abundant resources such as light, electricity, iron, and carbon dioxide.
José L. Araus - One of the best experts on this subject based on the ideXlab platform.
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the effect of Photoautotrophy on photosynthesis and photoinhibition of gardenia plantlets during micropropagation
Photosynthetica, 2001Co-Authors: Maria D. Serret, Maria I. Trillas, Josep Matas, José L. ArausAbstract:We studied the relationships between the degree of Photoautotrophy, photosynthetic capacity, and extent of photoinhibition of Gardenia jasminoides Ellis plantlets in vitro. Two successive micropropagation stages (shoot multiplication and root induction), and three culture conditions [tube cap closure, photosynthetic photon flux density (PPFD), and sucrose concentration] which may influence the development of Photoautotrophy in vitro were assayed. The ratios of variable chlorophyll fluorescence to either maximal (Fv/Fm) or ground (Fv/F0) values were low, irrespective of the culture stage or growing conditions. Incomplete development of the photosynthetic apparatus and permanent photoinhibition may be involved. However, Fv/Fm and Fv/F0 increased from shoot multiplication to root induction owing to a decrease in F0 and an increase in Fm. This suggests that photoinhibition decreases later during micropropagation, when the Photoautotrophy of plantlets is more advanced. The low sucrose content and high PPFD increased the photoinhibition of plantlets, whereas growth in tubes with permeable caps showed the opposite effect. The only culture factor with a significant (positive) effect on maximum photosynthetic rate (Pmax) was PPFD. At shoot multiplication net photosynthetic rate (PN) was positively correlated with the half time of the increase from F0 to Fm (t1/2). Such association may be mainly due to a common response of both traits to higher PPFD in culture. Within each culture stage, no relationship was observed between PN and the degree of Photoautotrophy, which was positively correlated with Fv/Fm and Fv/F0 during root induction. During shoot multiplication, these correlations were not significant, or were even negative. Hence during the last stage of micropropagation, plantlets with a higher degree of Photoautotrophy are less photoinhibited, whereas they do not follow this pattern at the earlier stage.
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The effect of different closure types, light, and sucrose concentrations on carbon isotope composition and growth ofGardenia jasminoides plantlets during micropropagation and subsequent acclimationex vitro
Plant Cell Tissue and Organ Culture, 1997Co-Authors: Maria D. Serret, Maria I. Trillas, Josep Matas, José L. ArausAbstract:The growth of Gardenia jasminoides Ellis plantlets and the development of Photoautotrophy during two successive culture stages (shoot multiplication and root induction) in vitro was analyzed. We examined the effects of changes in growth conditions (type of tube closure, light, and sugar levels) on the development of Photoautotrophy and growth during micropropagation and sought to establish whether they affected later acclimation to conditions ex vitro . During the two stages in vitro , plantlets were grown in tubes under two different PPFD (50 and 110 µmol m^−2 s^−1), in media with three different sucrose concentrations (0, 1.5, and 3.0%, w/v) and with two different CO_2 levels inside the tubes (controlled by either tightly closed caps or loosely sealed caps, and with an external CO_2 concentration of 750 µmol mol^−1). The development of Photoautotrophy was assessed by determining the difference between the stable carbon isotope composition (δ^13C) of sugar cane sucrose used as a heterotrophic carbon source and that of leaflets grown in vitro . Plantlets from the root-induction stage showed a more highly developed Photoautotrophy than those from the shoot- multiplication stage. At both stages, utilization of closed caps was the treatment which most stimulated development of Photoautotrophy in plantlets. Also, lowering PPFD or sucrose concentration induced a greater degree of photoautotrophic development, the strongest effect being observed in plantlets cultured inside loosely sealed tubes. During acclimation ex vitro , plantlets taken from loosely sealed tubes in vitro performed better than those cultured inside tightly sealed tubes. The former, as well as recording a larger increase in fresh weight during this stage, also showed more negative δ^13C in the newly developed leaves, which would seem to indicate a better water status during acclimation. Present results validate the usefulness of δ^13C analysis of leaflets as a simple technique in assessing the development of Photoautotrophy during culture in vitro . In addition, δ^13C analysis can be extended to evaluate growth conditions during acclimation to ex vitro conditions.
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Development of Photoautotrophy and photoinhibition of Gardenia jasminoides plantlets during micropropagation
Plant Cell Tissue and Organ Culture, 1996Co-Authors: Maria D. Serret, Maria I. Trillas, Josep Matas, José L. ArausAbstract:This paper reports on the fast fluorescence responses of Gardenia jasminoides Ellis plantlets, at two successive stages (shoot multiplication and root induction) of culture in vitro . We test whether plantlets in vitro suffer photoinhibition during culture and whether the degree of Photoautotrophy of these mixotrophic plantlets has any effect on the extent of photoinhibitory impairment. In this regard the effects of different sucrose levels in the medium and PPFD during growth on the development of Photoautotrophy and the extent of photoinhibition were evaluated. Plantlets were grown under low, intermediate, and high (50, 100, and 300 μmol m^-2 s^-1) PPFD, and at 3 different sucrose concentrations (0.5, 1.5, and 3.0%, w/v) in the medium, during shoot multiplication. During root induction the same growth conditions were assayed except for the high PPFD. The development of Photoautotrophy was assessed via the difference between the stable carbon isotope composition of sucrose used as heterotrophic carbon source and that of leaflets grown in vitro . Plantlets from root induction showed more developed Photoautotrophy than those from shoot multiplication. For both stages the low-sucrose medium stimulated the Photoautotrophy of plantlets in vitro . In addition, intermediate PPFD induced Photoautotrophy during shoot multiplication. For plantlets of both culture stages at the lowest PPFD no photoinhibition occurred irrespective of the sucrose concentration in media. However, during the shoot multiplication stage chlorophyll fluorescence measurements showed a decrease in F_ v /F_ m and in t _1/2 as growing PPFD increased, indicating photoinhibitory damage. The decline of F_ v /F_ m was caused mostly by an increase in F_ o , indicating the inactivation of PSII reaction centers. However plantlets growing under low sucrose showed reduced susceptibility to photoinhibition. During root induction, only plantlets cultured with high sucrose showed a decrease in F_ v /F_ m as PPFD increased, although t _1/2 remained unchanged. In this case, the decline of F_ v /F_ m was mostly due to a decrease in F_ m , which indicates increased photoprotection rather than occurrence of photodamage. Therefore, growth in low-sucrose media had a protective effect on the resistance of PSII to light stress. In addition, plantlets were more resistant to photoinhibition during root induction than during shoot multiplication. Results suggest that increased Photoautotrophy of plantlets reduces susceptibility to photoinhibition during gardenia culture in vitro .
Aran Incharoensakdi - One of the best experts on this subject based on the ideXlab platform.
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production of poly 3 hydroxybutyrate co 3 hydroxyvalerate under Photoautotrophy and heterotrophy by non heterocystous n2 fixing cyanobacterium
Bioresource Technology, 2017Co-Authors: Keerati Taepucharoen, Aran Incharoensakdi, Somchai Tarawat, Monthira Puangcharoen, Tanakarn MonshupaneeAbstract:The photoautotrophically grown cyanobacterium Oscillatoria okeni TISTR 8549 was found to produce bioplastic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). This PHBV production occurred under nitrogen deprivation (-N) that yielded PHBV accumulation of 14±4% (w/w DW) in which 3-hydroxyvalerate accounted for 5.5mol%. The heterotrophically grown (-N condition with acetate supplementation) cells under light showed no increase of PHBV storage, but under dark condition these cells increased PHBV accumulation to 42±8% (w/w DW) with 6.5mol% of 3-hydroxyvalerate. Compared to poly-3-hydroxybutyrate (PHB), the PHBV from O. okeni had a lower melting temperature by 5-7°C, a higher % elongation at break by 4-7times and a greater Young's elastic modulus by 2.3-2.5times.
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Two-stage (Photoautotrophy and heterotrophy) cultivation enables efficient production of bioplastic poly-3-hydroxybutyrate in auto-sedimenting cyanobacterium
Scientific Reports, 2016Co-Authors: Tanakarn Monshupanee, Palida Nimdach, Aran IncharoensakdiAbstract:Sustainable production of bioplastics by heterotrophic microbes has been restricted by the limited resources of organic substrates and the energy required for biomass harvest. Here, the easy-to-harvest cyanobacterium (Chlorogloea fritschii TISTR 8527), from which the biomass instantaneously settled to the bottom of liquid culture, was utilized to produce poly-3-hydroxybutyrate (PHB) using a two-stage cultivation strategy. The cells were first pre-grown under normal Photoautotrophy to increase their biomass and then recultivated under a heterotrophic condition with a single organic substrate to produce the product. Through optimization of this two-stage cultivation, the mass conversion efficiency of acetate substrate to PHB was obtained at 51 ± 7% (w/w), the comparable level to the theoretical biochemical conversion efficiency of acetate to PHB. This two-stage cultivation that efficiently converted the substrate to the product, concurrent with a reduced culture biomass, may be applicable for the production of other biopolymers by cyanobacteria.