The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
S V Aleksandrov - One of the best experts on this subject based on the ideXlab platform.
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Biological Production and eutrophication of Baltic Sea estuarine ecosystems: The Curonian and Vistula Lagoons
Marine Pollution Bulletin, 2010Co-Authors: S V AleksandrovAbstract:Abstract The long-term data on the temporal and spatial changes of chlorophyll and nutrients concentrations, phytoplankton biomass, primary Production and mineralization of organic matter in the Curonian and Vistula Lagoons were analyzed using seasonal data to 1994 and monthly data to 2007 at 9–12 stations. A comparison with hydrological (water temperature, salinity, water exchange) and chemical parameters indicate the main abiotic factors which influence the level of Biological Production and the trophic state of lagoons. Most of the Curonian Lagoon showed the strong summer warming-up of water (higher 20 °C) combined with freshwater conditions, slow-flow velocity and high concentrations of phosphorus which creates conditions for hyperblooms of Cyanobacteria. The Biological Production of the Vistula Lagoon is below the potentially possible level as the hydrodynamic activity (high-flow velocity) and brackish water prevent the intensive development of Cyanobacteria. The Curonian Lagoon may be considered as hypertrophic water body whereas the Vistula Lagoon is a eutrophic water body.
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Biological Production and eutrophication of Baltic Sea estuarine ecosystems: the Curonian and Vistula Lagoons.
Marine pollution bulletin, 2010Co-Authors: S V AleksandrovAbstract:The long-term data on the temporal and spatial changes of chlorophyll and nutrients concentrations, phytoplankton biomass, primary Production and mineralization of organic matter in the Curonian and Vistula Lagoons were analyzed using seasonal data to 1994 and monthly data to 2007 at 9-12 stations. A comparison with hydrological (water temperature, salinity, water exchange) and chemical parameters indicate the main abiotic factors which influence the level of Biological Production and the trophic state of lagoons. Most of the Curonian Lagoon showed the strong summer warming-up of water (higher 20 degrees C) combined with freshwater conditions, slow-flow velocity and high concentrations of phosphorus which creates conditions for hyperblooms of Cyanobacteria. The Biological Production of the Vistula Lagoon is below the potentially possible level as the hydrodynamic activity (high-flow velocity) and brackish water prevent the intensive development of Cyanobacteria. The Curonian Lagoon may be considered as hypertrophic water body whereas the Vistula Lagoon is a eutrophic water body.
Daniel Birgel - One of the best experts on this subject based on the ideXlab platform.
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Post-glacial variability of sea ice cover, river run-off and Biological Production in the western Laptev Sea (Arctic Ocean) – A high-resolution biomarker study
Quaternary Science Reviews, 2016Co-Authors: Tanja Hörner, Rüdiger Stein, Kirsten Fahl, Daniel BirgelAbstract:Abstract Multi-proxy biomarker measurements were applied on two sediment cores (PS51/154, PS51/159) to reconstruct sea ice cover (IP25), Biological Production (brassicasterol, dinosterol) and river run-off (campesterol, β-sitosterol) in the western Laptev Sea over the last ∼17 ka with unprecedented temporal resolution. The absence of IP25 from 17.2 to 15.5 ka, in combination with minimum concentration of phytoplankton biomarkers, suggests that the western Laptev Sea shelf was mostly covered with permanent sea ice. Very minor river run-off and restricted Biological Production occurred during this cold interval. From ∼16 ka until 7.5 ka, a long-term decrease of terrigenous (riverine) organic matter and a coeval increase of marine organic matter reflect the gradual establishment of fully marine conditions in the western Laptev Sea, caused by the onset of the post-glacial transgression. Intensified river run-off and reduced sea ice cover characterized the time interval between 15.2 and 12.9 ka, including the Bolling/Allerod warm period (14.7–12.9 ka). Prominent peaks of the DIP25 Index coinciding with maximum abundances of subpolar foraminifers, are interpreted as pulses of Atlantic water inflow on the western Laptev Sea shelf. After the warm period, a sudden return to severe sea ice conditions with strongest ice-coverage between 11.9 and 11 ka coincided with the Younger Dryas (12.9–11.6 ka). At the onset of the Younger Dryas, a distinct alteration of the ecosystem (reflected in a distinct drop in terrigenous and phytoplankton biomarkers) was detected. During the last 7 ka, the sea ice proxies reflect a cooling of the Laptev Sea spring/summer season. This cooling trend was superimposed by a short-term variability in sea ice coverage, probably representing Bond cycles (1500 ± 500 ka) that are related to solar activity changes. Hence, atmospheric circulation changes were apparently able to affect the sea ice conditions on the Laptev Sea shelf under modern sea level conditions.
Wenli Zhang - One of the best experts on this subject based on the ideXlab platform.
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Recent studies on the Biological Production of D-mannose.
Applied Microbiology and Biotechnology, 2019Co-Authors: Wenli ZhangAbstract:D-Mannose is an epimer of glucose at the C-2 position and exists in nature as a component of mannan. It has 60 and 86% sweetness than that of sucrose and D-glucose, respectively. Because of its low-calorie and nontoxic features, D-mannose is used widely in food, medicine, cosmetic, and food-additive industries. Besides, it exhibits many physiologic benefits on health: immune system, diabetes mellitus, intestinal diseases, and urinary tract infections. It is used as a starting material to synthesize immunostimulatory agents, anti-tumor agents, vitamins, and D-mannitol. However, D-mannose Production using chemical synthesis and plant extraction cannot meet the requirements of the industry. This article presents recent research on the Biological Production of D-mannose. The physiologic benefits and applications of D-mannose are summarized. Besides, different D-mannose-producing enzymes from various sources are discussed in detail with regard to their biochemical characteristics, catalytic efficiency, and reaction kinetics for D-mannose Production. Furthermore, attempts to use enzymatic conversion to produce D-mannose are reviewed.
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An overview on Biological Production of functional lactose derivatives.
Applied microbiology and biotechnology, 2019Co-Authors: Yaqin Xiao, Cuie Guang, Qiuming Chen, Wenli ZhangAbstract:Lactose is a natural disaccharide obtained from the milk of most mammals and a waste product of cheese and casein manufacturing. Over the past decades, lactose in whey has increasingly been promoted as an important resource, and an increasing number of significant advances have been made to investigate its healthy and functional properties. Lactose can be biotransformed into many kinds of derivatives, including galacto-oligosaccharides, epilactose, lactulose, lactosucrose, and D-tagatose. Biological efficiency and safety are critical for the enzymatic Production of lactose derivatives from lactose. These lactose derivatives show a range of prominent physiological features and effects, such as prebiotic properties, indigestibility, and obesity prevention, which can be utilized in the pharmaceutical, health, and food industries. In this review, we present the properties and physiological effects of lactose derivatives, detailing their Biological Production by various enzymes and their applications in dairy products, especially directly in the milk industry.
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Recent progress on Biological Production of α-arbutin.
Applied Microbiology and Biotechnology, 2018Co-Authors: Xingtong Zhu, Yuqing Tian, Wenli Zhang, Tao Zhang, Cuie GuangAbstract:Arbutin, a glucoside of hydroquinone, is used as a powerful skin lightening agent in the cosmeceutical industry because of its strong inhibitory effect on the human tyrosinase activity. It is a natural compound occurring in a number of plants, with a β-anomeric form of the glycoside bond between glucose and hydroquinone. α-Arbutin, which glycoside bond is generated with α-anomeric form, is the isomer of natural arbutin. α-Arbutin is generally produced by transglucosylation of hydroquinone by microbial glycosyltransferases. It is interesting that α-arbutin is found to be over 10 times more effective than arbutin, and thus Biological Production of α-arbutin attracts increasing attention. Seven different microbial enzymes have been identified to be able to produce α-arbutin, including α-amylase, sucrose phosphorlase, cyclodextrin glycosyltransferase, α-glucosidase, dextransucrase, amylosucrase, and sucrose isomerase. In this work, enzymatic and microbial Production of α-arbutin is reviewed in detail.
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Recent advances on Biological Production of difructose dianhydride III
Applied microbiology and biotechnology, 2018Co-Authors: Yingying Zhu, Tao Zhang, Wenli Zhang, Cuie GuangAbstract:Difructose dianhydride III (DFA III) is a cyclic difructose containing two reciprocal glycosidic linkages. It is easily generated with a small amount by sucrose caramelization and thus occurs in a wide range of food-stuffs during food processing. DFA III has half sweetness but only 1/15 energy of sucrose, showing potential industrial application as low-calorie sucrose substitute. In addition, it displays many benefits including prebiotic effect, low cariogenicity property, and hypocholesterolemic effect, and improves absorption of minerals, flavonoids, and immunoglobulin G. DFA III is Biologically produced from inulin by inulin fructotransferase (IFTase, EC 4.2.2.18). Plenty of DFA III-producing enzymes have been identified. The crystal structure of inulin fructotransferase has been determined, and its molecular modification has been performed to improve the catalytic activity and structural stability. Large-scale Production of DFA III has been studied by various IFTases, especially using an ultrafiltration membrane bioreactor. In this article, the recent findings on physiological effects of DFA III are briefly summarized; the research progresses on identification, expression, and molecular modification of IFTase and large-scale Biological Production of DFA III by IFTase are reviewed in detail.
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Recent advances in d-allulose: Physiological functionalities, applications, and Biological Production
Trends in Food Science & Technology, 2016Co-Authors: Wenli Zhang, Tao Zhang, Bo JiangAbstract:Abstract Background d -Allulose, an epimer of d -fructose, is a rare monosaccharide that exists in extremely small quantities in nature. It is an ideal substitute for sucrose, because it has 70% of the sweetness of sucrose and ultra-low the energy. In addition, it has received sustained attention because of its unique physiological functions and potential health benefits. However, it is scarce in nature, and difficult to chemically synthesize. Scope and approach Because of its scarcity, bioconversion of d -allulose is attractive to researchers. It has been demonstrated that ketose 3-epimerase plays an irreplaceable role in the bioconversion of d -fructose to d -allulose. Herein, an overview of recent advances regarding the physiological functions as well as the Biological Production of d -allulose is provided. Additionally, a comparison of the biochemical properties and a structural analysis of ketose 3-epimerases are also reviewed in detail in this paper. Key findings and conclusions Up to now, ketose 3-epimerase has been experimentally identified and characterized from only twelve types of microorganisms. In addition, 4 types of crystal structures from ketose 3-epimerases have been already solved, and the catalytic mechanism has also been proposed. However, the researches on molecular modification of ketose 3-epimerase are very few. In the future, molecular modification to improve the enzyme activity and thermostability through site-directed mutagenesis or directed evolution must be the research focus.
Tanja Hörner - One of the best experts on this subject based on the ideXlab platform.
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Post-glacial variability of sea ice cover, river run-off and Biological Production in the western Laptev Sea (Arctic Ocean) – A high-resolution biomarker study
Quaternary Science Reviews, 2016Co-Authors: Tanja Hörner, Rüdiger Stein, Kirsten Fahl, Daniel BirgelAbstract:Abstract Multi-proxy biomarker measurements were applied on two sediment cores (PS51/154, PS51/159) to reconstruct sea ice cover (IP25), Biological Production (brassicasterol, dinosterol) and river run-off (campesterol, β-sitosterol) in the western Laptev Sea over the last ∼17 ka with unprecedented temporal resolution. The absence of IP25 from 17.2 to 15.5 ka, in combination with minimum concentration of phytoplankton biomarkers, suggests that the western Laptev Sea shelf was mostly covered with permanent sea ice. Very minor river run-off and restricted Biological Production occurred during this cold interval. From ∼16 ka until 7.5 ka, a long-term decrease of terrigenous (riverine) organic matter and a coeval increase of marine organic matter reflect the gradual establishment of fully marine conditions in the western Laptev Sea, caused by the onset of the post-glacial transgression. Intensified river run-off and reduced sea ice cover characterized the time interval between 15.2 and 12.9 ka, including the Bolling/Allerod warm period (14.7–12.9 ka). Prominent peaks of the DIP25 Index coinciding with maximum abundances of subpolar foraminifers, are interpreted as pulses of Atlantic water inflow on the western Laptev Sea shelf. After the warm period, a sudden return to severe sea ice conditions with strongest ice-coverage between 11.9 and 11 ka coincided with the Younger Dryas (12.9–11.6 ka). At the onset of the Younger Dryas, a distinct alteration of the ecosystem (reflected in a distinct drop in terrigenous and phytoplankton biomarkers) was detected. During the last 7 ka, the sea ice proxies reflect a cooling of the Laptev Sea spring/summer season. This cooling trend was superimposed by a short-term variability in sea ice coverage, probably representing Bond cycles (1500 ± 500 ka) that are related to solar activity changes. Hence, atmospheric circulation changes were apparently able to affect the sea ice conditions on the Laptev Sea shelf under modern sea level conditions.
Jan Kaiser - One of the best experts on this subject based on the ideXlab platform.
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High-resolution net and gross Biological Production during a Celtic Sea spring bloom
Progress in Oceanography, 2019Co-Authors: Isabel Seguro, Alina Marca, S. J. Painting, Jamie D. Shutler, David J. Suggett, Jan KaiserAbstract:Abstract Shelf seas represent only 10% of the ocean area, but support up to 30% of all oceanic primary Production. There are few measurements of shelf-sea Biological Production at high spatial and temporal resolution in such heterogeneous and physically dynamic systems. Here, we use dissolved oxygen-to-argon (O2/Ar) ratios and oxygen triple isotopes (16O, 17O, 18O) to estimate net and gross Biological Production in the Celtic Sea during spring 2015. O2/Ar ratios were measured continuously using a shipboard membrane inlet mass spectrometer (MIMS). Additional discrete water samples from CTD hydrocasts were used to measure O2/Ar depth profiles and the δ(17O) and δ(18O) values of dissolved O2. These high-resolution data were combined with wind-speed based gas exchange parameterisations to calculate Biologically driven air-sea oxygen fluxes. After correction for disequilibrium terms and diapycnal diffusion, these fluxes yielded estimates of net community (N(O2/Ar)) and gross O2 Production (G(17O)). N(O2/Ar) was spatially heterogeneous and showed predominantly autotrophic conditions, with an average of (33 ± 41) mmol m−2 d−1. G(17O) showed high variability between 0 and 424 mmol m−2 d−1. The ratio of N(O2/Ar) to G(17O), ƒ(O2), was (0.18 ± 0.03) corresponding to 0.34 ± 0.06 in carbon equivalents. We also observed rapid temporal changes in N(O2/Ar), e.g. an increase of 80 mmol m−2 d−1 in
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Ocean glider observations of iceberg-enhanced Biological Production in the northwestern Weddell Sea
Geophysical Research Letters, 2015Co-Authors: Louise C. Biddle, Jan Kaiser, Karen J. Heywood, Andrew F. Thompson, Adrian JenkinsAbstract:Icebergs affect local Biological Production around Antarctica. We used an ocean glider to observe the effects of a large iceberg that was advected by the Antarctic Slope Current along the continental slope in the northwestern Weddell Sea in early 2012. The high-resolution glider data reveal a pronounced effect of the iceberg on ocean properties, with oxygen concentrations of (13 ± 4) μmol kg−1 higher than levels in surrounding waters, which are most likely due to positive net community Production. This response was confined to three areas of water in the direct vicinity of the iceberg track, each no larger than 2 km2. Our findings suggest that icebergs have an impact on Antarctic Production presumably through local micronutrient injections, on a scale smaller than typical satellite observations of Biological Production in the Southern Ocean.