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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Optimization of protein extraction from red algae

Kasparaviciute, Deimante January 2024 (has links)
The plastid is an important organelle that allows eukaryotes to photosynthesize. The endosymbiotic event that led to the development of a primary plastid occurred more than one billion years ago. Since then the organelle has undergone a significant genome reduction, losing a large portion of non-essential genes whose function is covered by the eukaryotic host. The majority of the proteins needed for essential plastid function are transcribed in the nucleus and translated in the cytosol. These proteins are then translocated across the inner and outer plastid membranes. The difference in where proteins are translated and transported can be used to study plastid evolution, this can be done by examining what proteins are present in the red algae plastid and comparing it to proteins found in other algae groups. In this project, the exact placement of the proteins, mainly plastid proteins is of interest. In order to localize and identify proteins in the algal cell, an efficient method of cell lysis, both total and incomplete, where the preservation of organelles is essential needs to be developed. This thesis examines a set of different methods of cell lysis, both complete and incomplete, coupled with organelle fractionation, to achieve the isolation of proteins belonging to the different cellular compartments. I show that complete cell lysis with bead milling using 0.1-0.5 mm silica beads is more efficient than a method using a Dounce homogenizer. For incomplete lysis, I show that nitrogen cavitation at 750 psi for 15 min and 1,000 psi for 30 min provides the same level of cellular lysis, indicating that the nitrogen gas equilibrates within 15 minutes. Organelle fractionation with OptiprepTM gradient showed that the majority of the sample did not travel through the gradient, staying in the first layer, which also prevented revelation of the protein pattern on an SDS-PAGE gel, indicating insufficient centrifugation. A great deal of optimization is still required to make these methods as efficient as possible. The step that requires the most optimization is sample preparation for nitrogen cavitation and the use of an ultracentrifuge.
62

Développement d’une méthode de déconvolution pharmacophorique pour la découverte accélérée d’antipaludiques chez les Rhodophytes / Development of a pharmacophoric deconvolution method to accelerate the antimalarial discovery from Rhodophyta

Margueritte, Laure 21 September 2018 (has links)
L’apparition de P. falciparum résistants aux CTAs est un problème majeur en Asie du Sud-Est. Il est nécessaire de rechercher des molécules présentant des mécanismes d’actions nouveaux. Une cible d’intérêt est l’apicoplaste, un organite de Plasmodium issu d’une endosymbiose avec une algue rouge. Les algues rouges pourraient présenter une source privilégiée de nouvelles molécules antipaludiques ciblant notamment les voies de biosynthèse apicoplastique. Cette thèse porte sur l’identification de ces métabolites secondaires bioactifs via le développement d’une nouvelle stratégie analytique. Un programme informatique nommé Plasmodesma a été créé et permet l’analyse différentielle de manière automatique de spectres RMN 2D 1H-1H et 1H-13C. Les molécules actives peuvent ensuite être isolées et identifiées par HPLC-SPE-RMN. L’activité antipaludique mise en évidence dans les algues rouges étudiées serait due à la présence de molécules de classes chimiques différentes dont des stérols. / Malaria is responsible for 445 000 deaths in 2016. The emergence and the spread of resistant P. falciparum to artemisinin-based combinations is a major health problem in South-East Asia. Research must continue to find compounds with a novel mechanism of action. The apicoplast is an interesting target. It is a Plasmodium organelle derived from a secondary endosymbiosis with a red alga. Red algae could be a special source of new antiplasmodial compounds targeting the isoprenoid biosynthesis pathway in the apicoplast. This thesis focuses on bioactive secondary metabolites identification via a new analytical strategy. A computer program called Plasmodesma was created and achieves an automatic differential analysis of 1H-1H and 1H-13C 2D NMR spectra. Bioactive compounds are isolated and identified by hyphenated HPLC-SPE-NMR. The presence of different classes of compounds including sterols could explain the antiplasmodial activity in studied the red algae species.
63

Atividades biol?gicas de polissacar?deos sulfatados extra?dos da alga vermelha Gracilaria caudata

Costa, Leandro Silva 23 December 2008 (has links)
Made available in DSpace on 2014-12-17T14:03:29Z (GMT). No. of bitstreams: 1 LeandroSC.pdf: 650975 bytes, checksum: 6025a0ab11422614586386d571f936a6 (MD5) Previous issue date: 2008-12-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In recent years, sulfated polysaccharides (SP) from marine algae have emerged as an important class of natural biopolymers with potential pharmacology applications. Among these, SP isolated from the cell walls of red algae have been study due to their anticoagulant,antithrombotic and anti-inflammatory activities. In the present study, three sulfated polysaccharides fractions denominated F1.5v, F2.0v and F3.0v were obtained from seaweed G. caudate by proteolysis followed to acetone fractionation. Gel electrophoresis using 0.05 M 1,3-diaminopropane-acetate buffer, pH 9,0, stained with 0.1% toluidine blue, showed the presence of SP in all fractions. The chemical analysis demonstrated that all the fractions are composed mainly of galactose. These compounds were evaluated in anticoagulant, antioxidant and antiproliferative activities. In anticoagulant activity evaluated through aPTT and PT tests, no one fractions presented anticoagulant activity at tested concentrations (0.1 mg/mL; 1.0 mg/mL; 2.0 mg/mL).The antioxidant activities of the three fractions were evaluated by the following in vitro systems: Total antioxidant capacity, superoxide and hydroxyl radical scavenging, ferrous chelating activity and reducing power. The fractions were found to have different levels of antioxidant activity in the systems tested. F1.5v shows the highest activity, especially in the ferrous chelating system, with 70% of ferrous inhibiting at 1.0 mg.mL-1. Finally, all the fractions showed dose-dependent antiproliferative activity against HeLa cells. The fractions F1.5v and F2.0v presented the highest antiproliferative activity at 2.0 mg/mL with 42.7% and 37.0% of inhibition, respectively. Ours results suggests that the sulfated polysaccharides from seaweed G. caudata are promising compounds in antioxidant and/or antitumor therapy / Nos ?ltimos anos, os polissacar?deos sulfatados de algas marinhas t?m emergido como uma importante classe de biopol?meros naturais com potenciais aplica??es farmacol?gicas. Dentre estas, os polissacar?deos sulfatados de algas vermelhas tem sido extensivamente estudados, principalmente devido seu potencial anticoagulante, antitromb?tico e antiinflamat?rio. Neste estudo, tr?s fra??es de polissacar?deos sulfatados, denominadas F1,5v, F2,0v e F3,0v, foram extra?das da alga vermelha Gracilaria caudata, atrav?s de prote?lise, seguida de fracionamento com acetona. Eletroforese em gel de agarose em Tamp?o PDA mostrou a presen?a de polissacar?deos sulfatados em todas as fra??es. As an?lises qu?micas demonstraram que todas as fra??es s?o compostas principalmente de galactose. Esses compostos foram testados para as atividades anticoagulante, antioxidante e antiproliferativa. Na atividade anticoagulante avaliada atrav?s de kits comerciais de aPTT e PT, nenhuma das fra??es apresentou atividade nas concentra??es testadas (0,1; 0,5 e 1,0 mg/mL). A atividade antioxidante das fra??es polissacar?dicas foi avaliada atrav?s de diversos ensaios in vitro: Capacidade antioxidante total, seq?estro de radical super?xido e hidroxila, quela??o f?rrica e poder redutor. As fra??es apresentaram diferentes n?veis de atividade antioxidante nos sistemas testados. A fra??o F1,5v apresentou a maior atividade antioxidante, principalmente no ensaio de quela??o f?rrica, com cerca de 70,00% de inibi??o na concentra??o de 1,0 mg/mL. Finalmente, todas as fra??es apresentaram atividade antiproliferativa dose-dependente frente a linhagem celular tumoral HeLa. As fra??es F1,5v e F2,0v apresentaram as maiores atividades antiproliferativa na concentra??o de 2,0 mg/mL, com 42,70% e 37,00% de inibi??o da prolifera??o celular em rela??o ao controle. Nossos resultados sugerem que os polissacar?deos sulfatados de G. caudata s?o promissores f?rmacos na terapia antioxidante e/ou antiproliferativa
64

Aplicação de cromatografia gasosa acoplada à espectrometria de massas na identificação de substâncias obtidas de algas marinhas de dois estados do Nordeste brasileiro / Application of gas chromatrography-mass spectrometry to identify substances obtained from seaweed of two states in Northeastern Brazil

Silva, Daniel Lira da 26 August 2014 (has links)
Seaweeds are organisms which live in oceans and seas. They have ability to perform photosynthesis and feed many species of aquatic organisms. Macroalgae, which can be divided by characteristic colors in: Red algae (Phylum Rhodopyta), Green algae (Phylum Chlorophyta) and Brown algae (Class Phaeophyceae). Seaweeds are used for centuries by Asians as an important part of their diet, and also as source of compounds to Pharmaceutical and Cosmetic industries. The Brazilian Northeastern has a large coastal area; it possesses several forms of marine organisms especially for being in a Tropical hot water zone. Based on the importance of macroalgae, a chemical study was conducted using five species of algae (Bryothamnion seaforthii; Colpomenia sinuosa; Dictyosphaeria versluysii, Digenea simplex and Galaxaura rugosa) to prepare methanolic extracts and sequential fractions. 72 substances were identified using the GC-MS technique under the following operation conditions: helium as the carrier gas; 1.52 mL/min flow rate; oven temperature 60 º (25 ºC/min 300 ºC, heating rate); Splitless; injected volume 1 μL; solvent cutting 3 minutes. The mass spectra were obtained in the same equipment by electron impact ionization (EI) at 70 eV; and the ion source was maintained at 300 ° C. Hexadecanoic acid, in all fractions; 1-isopropyl-1,3,4-trimethyl-cyclohexane, 1,4-diisopropyl-cyclohexane and isopentyl decanoate, first identified in seaweeds; several esters, hydrocarbons and fatty acids can be mentioned as identified substances. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Alga é uma forma de vida que vive em oceanos e mares e possui a capacidade de realizar fotossíntese e servir de alimento e/ou abrigo para muitas espécies de organismos aquáticos. As macroalgas, que podem ser divididas pela cor característica que possuem, em algas vermelhas (Filo Rhodophyta), verdes (Filo Chlorophyta) e pardas (Classe Phaeophyceae), são utilizadas pelos orientais como parte importante de sua alimentação há vários séculos, além de utilizá-las como fonte de produtos farmacêuticos e da indústria de cosméticos. O nordeste brasileiro possui uma vasta área litorânea e costeira sendo rico em diversas formas de vida marinha, principalmente por estar em uma zona tropical de águas quentes. Com base na importância destas macroalgas, foi realizado um estudo químico de cinco espécies de algas, Bryothamnion seaforthii, Colpomenia sinuosa, Dictyospharia versluysii, Digenea simplex e Galaxaura rugosa, através de extratos metanólicos e frações. A técnica de cromatografia gasosa acoplada à espectroscopia de massas foi utilizada com as seguintes condições de operação: hélio como gás de arraste; velocidade do fluxo, 1,52 mL/min; a temperatura inicial do forno foi 60 ºC, com uma taxa de aquecimento de 25 ºC/min até 300 ºC; “Splitless”, como modo de injeção; 1 μL de volume injetado; e corte do solvente em 3 minutos. O tempo total de corrida foi 25 minutos. Os espectros de massas foram obtidos no mesmo equipamento, através de ionização por impacto de elétrons (EI) de 70 eV; e a fonte de íons foi mantida a 300 ºC. Desse modo foram identificadas 72 substâncias, dentre as quais podem ser citadas: ácido hexadecanoico, presente em todas as frações; os hidrocarbonetos 1-isopropil-1,3,4-trimetilcicloexano, 1,4-di-isopropilcicloexano e decanoato de isopentila, identificados pela primeira vez em algas; além de diversos ésteres, hidrocarbonetos e ácidos graxos.
65

Produtos naturais marinhos: identificação de metabólitos fenólicos halogenados na macroalga Bostrychia tenella (Rhodomelaceae, Rhodophyta) e potencial biológico de micro-organismos endofíticos associados / Marine natural products: halophenolic metabolites identification in the seaweed Bostrychia tenella (Rhodomelaceae, Rhodophyta) and biological potential of associated endophytic microorganisms

Rafael de Felício 07 October 2010 (has links)
O ambiente marinho desponta como uma fonte natural importante devido à sua fantástica diversidade orgânica, que permanece praticamente inexplorada. Abordagens químicas e biológicas de organismos marinhos, atualmente, representam uma área de pesquisa ampla e promissora, visto a constante descoberta de diversos metabólitos com propriedades medicinais variadas, além de um arsenal metabólico praticamente ilimitado. Algas vermelhas, com destaque para a família Rhodomelaceae, são exímias produtoras de metabólitos halogenados aos quais são atribuídos importantes atividades biológicas. Micro-organismos marinhos e/ou endofíticos são apontados como os alvos mais promissores para descoberta de novos fármacos. Neste contexto, o presente trabalho descreve a identificação de metabólitos secundários da macroalga Bostrychia tenella (Rhodomelaceae, Rhodophyta), a qual possui poucos relatos na literatura a respeito de seu metabolismo secundário, bem como o potencial biológico de micro-organismos endofíticos associados a esta espécie. O estudo químico da espécie B. tenella coletada nos costões rochosos da Praia da Fortaleza (Ubatuba-SP) proporcionou a identificação, por meio de análises via CG-EM (fração acetato), de 63 metabólitos dos quais 39 são substâncias apolares de cadeias carbônicas longas (ex. ácidos graxos e ésteres, esteróides, dentre outros) e 24 são metabólitos fenólicos, incluindo 17 halofenóis clorados, bromados e iodados. Destas 24 substâncias, até o presente momento, três são inéditas, nove são inéditas como produtos naturais, quatro são inéditas em algas marinhas e seis são inéditas para o gênero Bostrychia. Adicionalmente, 45 linhagens de micro-organismos endofíticos foram isoladas da alga Bostrychia tenella, das quais 10 foram cultivadas em meio sólido arroz, proporcionando a obtenção de extratos brutos e frações orgânicas. Apesar das frações de B. tenella não terem exibido atividade biológica, extratos e frações dos micro-organismos endofíticos associados a esta espécie apresentaram-se ativos em todos os ensaios realizados: citotoxicidade utilizando células tumorais HL-60, HCT-8 e SF-295, antifúngico utilizando fitopatógenos Cladosporium cladosporioides e C. sphaerospermum, antibacteriano utilizando Staphylococcus aureus e Klebsiella pneumoniae, e inibição da degranulação mastocitária utilizando células RBL-2H3. O presente trabalho contribuiu para aumento do conhecimento sobre o metabolismo secundário da alga Bostrychia tenella e proporcionou a descoberta do potencial biológico de micro-organismos endofíticos associados a esta alga, atribuindo a esta espécie relevância química e microbiológica para o estudo de produtos naturais marinhos. / The marine environment appears as an important natural source due to its fantastic organic diversity, which practically remains unexplored. Chemical and biological approaches concerning marine organism, currently, represent an ample and promising research area, since there are a constant metabolite discovery with a variety of medicinal properties, besides the limitless metabolic armory. Red seaweeds, with distinction for the Rhodomelaceae family, are exempt of halogenated metabolites producers which are attributed important biological activities. Marine and/or endophytic microorganisms are pointed as the most promising targets with respect to discovery of new pharmaceuticals. In this context, the present work describes the secondary metabolites identification from seaweed Bostrychia tenella (Rhodomelaceae, Rhodophyta), as well as the biological potential of associated endophytic microorganisms. The chemical study of B. tenella species collected in the rocky shore of Praia de Fortaleza (Ubatuba-SP) provided the identification, by means of GC-MS analyses (acetate fraction), of 63 metabolites, which 39 consisted of nonpolar substances containing a long carbonic chains (fatty acids, esters, steroids, amongst others) and 24 were phenolic compounds, including 17 chlorinated, bromated and iodized halophenols. Related to these 24 substances, until the present moment, three are unknown, nine are unknown as natural products, four are unknown in seaweeds and six are unknown in the Bostrychia genus. Additionally, 45 endophytic microorganism strains had been isolated from B. tenella, from which 10 were cultivated in solid rice medium, providing several crude extracts and fractions. Although the B. tenella fractions did not show biological potential, extracts and fractions from endophytic microorganism associates to this species presented biological activity in all of evaluated assays: cytotoxicity using tumor cells HL-60, HCT-8 and SF-295, antifungal in Cladosporium cladosporioides and C. sphaerospermum, antibacterial using Staphylococcus aureus and Klebsiella pneumoniae, and mast cell degranulation inhibition using RBL-2H3 cells. The present work contributed for the secondary metabolism knowledge increase regarding Bostrychia tenella species, and demonstrated the endophytic microorganism biological potential, attributing to this species chemical and microbiological relevance for the marine natural products research.
66

Produtos naturais marinhos: identificação de metabólitos fenólicos halogenados na macroalga Bostrychia tenella (Rhodomelaceae, Rhodophyta) e potencial biológico de micro-organismos endofíticos associados / Marine natural products: halophenolic metabolites identification in the seaweed Bostrychia tenella (Rhodomelaceae, Rhodophyta) and biological potential of associated endophytic microorganisms

Felício, Rafael de 07 October 2010 (has links)
O ambiente marinho desponta como uma fonte natural importante devido à sua fantástica diversidade orgânica, que permanece praticamente inexplorada. Abordagens químicas e biológicas de organismos marinhos, atualmente, representam uma área de pesquisa ampla e promissora, visto a constante descoberta de diversos metabólitos com propriedades medicinais variadas, além de um arsenal metabólico praticamente ilimitado. Algas vermelhas, com destaque para a família Rhodomelaceae, são exímias produtoras de metabólitos halogenados aos quais são atribuídos importantes atividades biológicas. Micro-organismos marinhos e/ou endofíticos são apontados como os alvos mais promissores para descoberta de novos fármacos. Neste contexto, o presente trabalho descreve a identificação de metabólitos secundários da macroalga Bostrychia tenella (Rhodomelaceae, Rhodophyta), a qual possui poucos relatos na literatura a respeito de seu metabolismo secundário, bem como o potencial biológico de micro-organismos endofíticos associados a esta espécie. O estudo químico da espécie B. tenella coletada nos costões rochosos da Praia da Fortaleza (Ubatuba-SP) proporcionou a identificação, por meio de análises via CG-EM (fração acetato), de 63 metabólitos dos quais 39 são substâncias apolares de cadeias carbônicas longas (ex. ácidos graxos e ésteres, esteróides, dentre outros) e 24 são metabólitos fenólicos, incluindo 17 halofenóis clorados, bromados e iodados. Destas 24 substâncias, até o presente momento, três são inéditas, nove são inéditas como produtos naturais, quatro são inéditas em algas marinhas e seis são inéditas para o gênero Bostrychia. Adicionalmente, 45 linhagens de micro-organismos endofíticos foram isoladas da alga Bostrychia tenella, das quais 10 foram cultivadas em meio sólido arroz, proporcionando a obtenção de extratos brutos e frações orgânicas. Apesar das frações de B. tenella não terem exibido atividade biológica, extratos e frações dos micro-organismos endofíticos associados a esta espécie apresentaram-se ativos em todos os ensaios realizados: citotoxicidade utilizando células tumorais HL-60, HCT-8 e SF-295, antifúngico utilizando fitopatógenos Cladosporium cladosporioides e C. sphaerospermum, antibacteriano utilizando Staphylococcus aureus e Klebsiella pneumoniae, e inibição da degranulação mastocitária utilizando células RBL-2H3. O presente trabalho contribuiu para aumento do conhecimento sobre o metabolismo secundário da alga Bostrychia tenella e proporcionou a descoberta do potencial biológico de micro-organismos endofíticos associados a esta alga, atribuindo a esta espécie relevância química e microbiológica para o estudo de produtos naturais marinhos. / The marine environment appears as an important natural source due to its fantastic organic diversity, which practically remains unexplored. Chemical and biological approaches concerning marine organism, currently, represent an ample and promising research area, since there are a constant metabolite discovery with a variety of medicinal properties, besides the limitless metabolic armory. Red seaweeds, with distinction for the Rhodomelaceae family, are exempt of halogenated metabolites producers which are attributed important biological activities. Marine and/or endophytic microorganisms are pointed as the most promising targets with respect to discovery of new pharmaceuticals. In this context, the present work describes the secondary metabolites identification from seaweed Bostrychia tenella (Rhodomelaceae, Rhodophyta), as well as the biological potential of associated endophytic microorganisms. The chemical study of B. tenella species collected in the rocky shore of Praia de Fortaleza (Ubatuba-SP) provided the identification, by means of GC-MS analyses (acetate fraction), of 63 metabolites, which 39 consisted of nonpolar substances containing a long carbonic chains (fatty acids, esters, steroids, amongst others) and 24 were phenolic compounds, including 17 chlorinated, bromated and iodized halophenols. Related to these 24 substances, until the present moment, three are unknown, nine are unknown as natural products, four are unknown in seaweeds and six are unknown in the Bostrychia genus. Additionally, 45 endophytic microorganism strains had been isolated from B. tenella, from which 10 were cultivated in solid rice medium, providing several crude extracts and fractions. Although the B. tenella fractions did not show biological potential, extracts and fractions from endophytic microorganism associates to this species presented biological activity in all of evaluated assays: cytotoxicity using tumor cells HL-60, HCT-8 and SF-295, antifungal in Cladosporium cladosporioides and C. sphaerospermum, antibacterial using Staphylococcus aureus and Klebsiella pneumoniae, and mast cell degranulation inhibition using RBL-2H3 cells. The present work contributed for the secondary metabolism knowledge increase regarding Bostrychia tenella species, and demonstrated the endophytic microorganism biological potential, attributing to this species chemical and microbiological relevance for the marine natural products research.
67

Biomethanation of Red Algae from the Eutrophied Baltic Sea

Biswas, Rajib January 2009 (has links)
<p>In the semi-enclosed Baltic Sea, excessive filamentous macro-algal biomass growth as a result of eutrophication is an increasing environmental problem. Drifting huge masses of red algae of the genera <em>Polysiphonia</em>, <em>Rhodomela</em>, and <em>Ceramium</em> accumulate on the open shore, up to five tones of algae per meter beach. During the aerobic decomposition of these algal bodies, large quantities of red colored effluents leak into the water what are toxic for the marine environment. In this study, feasibility of anaerobic conversion of red algae <em>Polysiphonia</em>, rich in nitrogen and phosphorous, was investigated. Biogas and methane potential of <em>Polysiphonia</em>, harvested in two different seasons [October and March], was investigated through three different batch digestion experiments and laboratory scale CSTR [continuous stirred tank reactor] at mesophilic (37<sup>o</sup>C) condition. Autoclavation [steam and heat] and ultrasound pretreatments were applied in order to enhance the biodegradation. In STR, anaerobic codigestion of algal biomass with SS [sewage sludge] was applied with a gradual increase in organic loading rate [1.5-4.0 g VS/L/day] and operated for 117 days at 20days HRT [hydraulic retention time]. Reactor digestate was analyzed four times over the period to determine the nutrients and heavy metals content. It is concluded that the methane potential of algae harvested in October is almost two-fold than that of algae harvested in March, probably due to it’s higher [more than double] nitrogen richness. An increase in biogas yield was observed upto 28% and VS reduction was increased from 37% to 45% due to autoclave pretreatment. Ultrasound pretreatment had no effect on digestion. In batch digestion, maximum methane yield 0.25 m<sup>3</sup>/kg VS added at 273<sup>o</sup>K, was obtained from algae [harvested in October] pretreated in autoclave. Codigestion of algae with SS worked well in STR with a comparatively lower OLR. At a higher OLR, methanogens were inhibited due to increased VFAs accumulation and decreased pH. A maximum biogas yield 0.49 m<sup>3</sup>/kg VS added at 310<sup>o</sup>K , was obtained from algae [harvested in October] pretreated with autoclave. The methane content of the produced biogas was 54%. Average [over a short period, day 99-107, reactor showed steady performance] maximum biogas yields from untreated algae obtained 0.44 m3/kg VSadded at 310<sup>o</sup>K and the VS reduction was calculated 32%. Digestate, to be used as a fertilizer, was found NH<sub>4</sub>-N, N, P, K, S and Na rich and only Cadmium level was above the maximal limit among the heavy metals. The sand content in algae during harvesting was considered as a factor to disrupt the operation. Codigestion of <em>Polysiphonia</em> algal biomass with substrate with higher C:N ratio like paper mill waste should be more appropriate to increase the methane and biogas yield. It is inconclusive whether AD process is a good method to dewater redalgae or not but large scale harvesting of algae will definitely contribute to curb eutrophication of the Baltic Sea through decreasing N and P level.</p>
68

Biomethanation of Red Algae from the Eutrophied Baltic Sea

Biswas, Rajib January 2009 (has links)
In the semi-enclosed Baltic Sea, excessive filamentous macro-algal biomass growth as a result of eutrophication is an increasing environmental problem. Drifting huge masses of red algae of the genera Polysiphonia, Rhodomela, and Ceramium accumulate on the open shore, up to five tones of algae per meter beach. During the aerobic decomposition of these algal bodies, large quantities of red colored effluents leak into the water what are toxic for the marine environment. In this study, feasibility of anaerobic conversion of red algae Polysiphonia, rich in nitrogen and phosphorous, was investigated. Biogas and methane potential of Polysiphonia, harvested in two different seasons [October and March], was investigated through three different batch digestion experiments and laboratory scale CSTR [continuous stirred tank reactor] at mesophilic (37oC) condition. Autoclavation [steam and heat] and ultrasound pretreatments were applied in order to enhance the biodegradation. In STR, anaerobic codigestion of algal biomass with SS [sewage sludge] was applied with a gradual increase in organic loading rate [1.5-4.0 g VS/L/day] and operated for 117 days at 20days HRT [hydraulic retention time]. Reactor digestate was analyzed four times over the period to determine the nutrients and heavy metals content. It is concluded that the methane potential of algae harvested in October is almost two-fold than that of algae harvested in March, probably due to it’s higher [more than double] nitrogen richness. An increase in biogas yield was observed upto 28% and VS reduction was increased from 37% to 45% due to autoclave pretreatment. Ultrasound pretreatment had no effect on digestion. In batch digestion, maximum methane yield 0.25 m3/kg VS added at 273oK, was obtained from algae [harvested in October] pretreated in autoclave. Codigestion of algae with SS worked well in STR with a comparatively lower OLR. At a higher OLR, methanogens were inhibited due to increased VFAs accumulation and decreased pH. A maximum biogas yield 0.49 m3/kg VS added at 310oK , was obtained from algae [harvested in October] pretreated with autoclave. The methane content of the produced biogas was 54%. Average [over a short period, day 99-107, reactor showed steady performance] maximum biogas yields from untreated algae obtained 0.44 m3/kg VSadded at 310oK and the VS reduction was calculated 32%. Digestate, to be used as a fertilizer, was found NH4-N, N, P, K, S and Na rich and only Cadmium level was above the maximal limit among the heavy metals. The sand content in algae during harvesting was considered as a factor to disrupt the operation. Codigestion of Polysiphonia algal biomass with substrate with higher C:N ratio like paper mill waste should be more appropriate to increase the methane and biogas yield. It is inconclusive whether AD process is a good method to dewater redalgae or not but large scale harvesting of algae will definitely contribute to curb eutrophication of the Baltic Sea through decreasing N and P level.
69

Transcriptional Regulation of Select Light-Harvesting Genes during Photoacclimation in <i>Lympha mucosa</i> gen. et sp. prov. (Batrachospermales, Rhodophyta)

Evans, Joshua R. 19 September 2017 (has links)
No description available.

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