Literatura científica selecionada sobre o tema "Klebsormidium nitens"

Abstract This study aims at improving the existing algal-based wastewater treatment technologies by overcoming some of the major drawbacks of these systems such as large required land area, culture contamination, and energy-intensive algal harvesting. The experiments were carried out in an open photo-sequencing batch reactor at a laboratory-scale for nearly 2 months. A specific strain ACUS00207 of the aeroterrestrial green microalga Klebsormidium nitens (Kützing) Lokhorst was used. The strain is native to Bulgaria and belongs to a species that has never been used before in suspended growth systems for wastewater treatment for phosphorus removal. The culture of K. nitens showed promising results: phosphorus removal rates ranging from 0.4 to 1 mg total phosphorus L−1 d−1, efficient settling properties, and resistance to culture contamination with native microalgae. On the basis of the observed phosphorus removal mechanism of biologically mediated chemical precipitation/phosphorus precipitation, an innovative working mode of the sequencing batch reactor is suggested for reducing the hydraulic retention time and the required land area.

The work is focused to the selection of the best purification methods of microalgae strains from ACKU collection (Algae Culture Collection of Kyiv University) from contamination by microscopic fungi. The screening of microalgae culture collection ACKU (Algae Culture Collection of Kyiv University) is deal. Contamination of some microalgae strains by fungi of Cladosporium Link, Alternaria Nees, and Monilia Bonord genera was detected. The following strains were selected for the experiment: ACKU 139-02 (Klebsormidium flaccidum (Kütz.) PC Silva, Mattox et Blackwell), ACKU 293-04 (Acutodesmus obliquus (Turpin) P. Tsarenko), ACKU 364-04 (cf. Chlorosarcinopsis dissociata Herndon), ACKU 599-06 (Klebsormidium nitens Menegh. in Kützing), ACKU 600-06 (Klebsormidium flaccidum (Kütz.) PC Silva, Mattox et Blackwell) и ACKU 1056 (Desmodesmus abundans (Kirchn.) E. Hegew.). The effect of carbendazim (Methylbenzimidazol-2-ylcarbamate), Antibiotic Antimycotic Solution (penicillin – 10,000 IU, streptomycin – 10 mg, amphotericin B – 25 μg) and Nuosept BMc 422 on fungi-contaminants of green algal culture strains with different morphological structure (coccoid and filamentous) was studied. Experimental concentrations of substances: carbendazim – 0.005%, Antibiotic Antimycotic Solution – 1%, Nuosept BMc 422 – 0.05% and 0.2%. Was shown that Antibiotic-Antimycotic Solution and Nuosept BMc-422 at the selected concentrations were not effective for purifying of green algae strains from significant contamination by microscopic fungi. It was found that the carbendazim solution is effective in the purification of cocoid green algae strains from contamination by microscopic fungi Cladosporium cladosporioides (Fresen.) G.A. de Vries). As a result, an axenic culture was obtained for the ACKU strain No.293-04 (A. obliquus).

Volcanic activity has a significant influence on the development of terrestrial ecosystems, including the Kamchatka Peninsula. We aimed to study the terrestrial algoflora of the Mutnovsky and Gorely volcanoes based on the use of clonal cultures of algae and cyanobacteria, and phenotypic and molecular genetic analyses. A total of 48 taxa were identified: 9 cyanobacteria, 32 Chlorophyta (11 Chlorophyceae, 21 Trebouxiophyceae), 3 Ochrophyta, and 4 Charophyta. In soils of the Mutnovsky volcano, 30 taxa were found, and in soils of the Gorely volcano, 24 were observed. In the studied area, small coccoid or mucilage-producing algae, which belong to cosmopolitan species, were identified, including representatives of the genera Bracteacoccus, Chlorococcum, Coccomyxa, Coelastrella, Klebsormidium, Neocystis, and Vischeria. Certain taxa were detected for the first time in the studied region, including Bracteacoccus bullatus, Chlorococcum hypnosporum, Chlorococcum lobatum, Coccomyxa subellipsoidea, Klebsormidium nitens, Leptosira obovata, Lobosphaera incisa, Parietochloris pseudoalveolaris, Stenomitos tremulus, and Vischeria magna. Our analysis of the algal communities at different altitudes reveals expansion in species richness with increasing distance from the tops of the volcanoes. The obtained data allowed us to estimate the real biodiversity of terrestrial algae and cyanobacteria of Kamchatkan volcanic soils, as well as the ecologies of these microorganisms.

Algae-based wastewater treatment is a promising technology with various applications for excess biomass such as biofertilizer production or valuable elements extraction. The benefits of the technology have been discussed for larger wastewater treatment plants (WWTPs), but the use of microalgae in decentralized wastewater treatment has been barely reported. The current study screens the possible resource recovery potential of onsite technology, which adds algae-based post-treatment to the conventional biological treatment of domestic wastewater. The effluent from the onsite sequencing batch reactor (SBR) of a household was further processed in laboratory conditions using an SBR technology with two local monocultures of algae—Klebsormidium nitens (Kützing) Lokhorst and Tetradesmus obliquus (Turpin) M. J. Wynne. The decant and the generated algal biomass were analyzed in terms of their element content. The post-treated effluent has a slightly better quality for irrigation purposes than the effluent of the onsite treatment facility—up to 1.6 times increased concentration for macro-elements and up to 1.9 times for micro elements. However, the generated algal biomass shows promising potential for re-use as a fertilizing agent since it contains valuable macro- and micro-elements and the heavy (hazardous) metal content is considerably lower than the limiting values in the current European and national legislations. The K. nitens strain may attract interest since it accumulates valuable metals such as chromium (36 mg/kgDS), nickel (83 mg/kgDS), and silver (0.7 mg/kgDS) that can be derived from the biomass and turn the technology to a circular one.

Since vegetable oils (usually triacylglycerol [TAG]) are extensively used as food and raw materials, an increase in storage oil content and production of valuable polyunsaturated fatty acids (PUFAs) in transgenic plants is desirable. In this study, a gene encoding glycerol-3-phosphate acyltransferase 9 (GPAT9), which catalyzes the synthesis of lysophosphatidic acid (LPA) from a glycerol-3-phosphate and acyl-CoA, was isolated from Physcomitrella patens, which produces high levels of very-long-chain PUFAs in protonema and gametophores. P. patens GPAT9 shares approximately 50%, 60%, and 70% amino acid similarity with GPAT9 from Chlamydomonas reinhardtii, Klebsormidium nitens, and Arabidopsis thaliana, respectively. PpGPAT9 transcripts were detected in both the protonema and gametophores. Fluorescent signals from the eYFP:PpGPAT9 construct were observed in the ER of Nicotiana benthamiana leaf epidermal cells. Ectopic expression of PpGPAT9 increased the seed oil content by approximately 10% in Arabidopsis. The levels of PUFAs (18:2, 18:3, and 20:2) and saturated FAs (16:0, 18:0, and 20:0) increased by 60% and 43%, respectively, in the storage oil of the transgenic seeds when compared with the wild type. The transgenic embryos with increased oil content contained larger embryonic cells than the wild type. Thus, PpGPAT9 may be a novel genetic resource to enhance storage oil yields from oilseed crops.

Rice (Oryza sativa), a staple crop for a substantial part of the world’s population, is highly sensitive to soil salinity; however, some wild Oryza relatives can survive in highly saline environments. Sodium/hydrogen antiporter (NHX) family members contribute to Na+ homeostasis in plants and play a major role in conferring salinity tolerance. In this study, we analyzed the evolution of NHX family members using phylogeny, conserved domains, tertiary structures, expression patterns, and physiology of cultivated and wild Oryza species to decipher the role of NHXs in salt tolerance in Oryza. Phylogenetic analysis showed that the NHX family can be classified into three subfamilies directly related to their subcellular localization: endomembrane, plasma membrane, and tonoplast (vacuolar subfamily, vNHX1). Phylogenetic and structural analysis showed that vNHX1s have evolved from streptophyte algae (e.g., Klebsormidium nitens) and are abundant and highly conserved in all major land plant lineages, including Oryza. Moreover, we showed that tissue tolerance is a crucial trait conferring tolerance to salinity in wild rice species. Higher Na+ accumulation and reduced Na+ effluxes in leaf mesophyll were observed in the salt-tolerant wild rice species O. alta, O. latifolia, and O. coarctata. Among the key genes affecting tissue tolerance, expression of NHX1 and SOS1/NHX7 exhibited significant correlation with salt tolerance among the rice species and cultivars. This study provides insights into the evolutionary origin of plant NHXs and their role in tissue tolerance of Oryza species and facilitates the inclusion of this trait during the development of salinity-tolerant rice cultivars.

Le monoxyde d'azote (NO) est un composant ubiquitaire majeur de la signalisation cellulaire, exerçant ses effets en partie par la S-nitrosation des protéines. Cette modification post-traductionnelle peut impacter l’activité des protéines, leur localisation subcellulaire et leur capacité à former des complexes protéiques. Par conséquent, la caractérisation des protéines S-nitrosées est d'un grand intérêt pour élucider les fonctions du NO. Lors d’une précédente étude, notre laboratoire a fourni des preuves que les plantes terrestres ne possèdent pas de NO Synthase (NOS), l'enzyme principale de synthèse du NO chez les métazoaires (Jeandroz et al., 2016). En revanche, quelques espèces d'algues possèdent des protéines apparentées aux NOS, ce qui soulève des questions sur leur biochimie et leurs rôles dans ces organismes. Nous nous sommes concentrés sur l'identification des protéines S-nitrosées chez Klebsormidium nitens, une espèce d'algue d'eau douce possédant deux séquences apparentées à des NOS dans son génome (Chatelain et al., 2022) et considérée comme un modèle pour étudier l'adaptation des plantes à la vie terrestre (Hori et al., 2014). Nous avons identifié 43 protéines candidates présentant des niveaux significativement plus élevés de S-nitrosation en condition de stress salin. Une analyse d'orthologie a été effectuée avec Arabidopsis thaliana pour déterminer la fonction potentielle de ces protéines. Nous avons sélectionné 3 protéines parmi elles, afin d’étudier le rôle de leur S-nitrosation dans la réponse au stress salin. Ces protéines sont la Protéine Phosphatase 1 (PPH1), l’Histone Désacétylase 14 (HDA14) et l'Inositol Polyphosphate Multikinase 2 (IPK2).PPH1 est une protéine cruciale dans l’adaptation des plantes terrestres aux conditions lumineuses. La caractérisation de KnPPH1 a été entamée mais des difficultés sont rapidement survenues, notamment due à une mauvaise annotation de sa séquence dans les banques de données et une difficulté à la produire en système hétérologue. La protéine HDA14 d’A. thaliana et du riz est une histone désacétylase chloroplastique, responsable de la désacétylation de protéines impliquées dans la photosynthèse, ainsi que de la désacétylation de la N-acétyl-sérotonine en sérotonine, des précurseurs à la synthèse de mélatonine. La séquence de KnHDA14 a été vérifiée, ainsi que sa localisation chloroplastique. Nous avons pu la produire en système bactérien et avons confirmé son activité de désacétylase, laquelle semblerait inhibée par le NO. Enfin, chez A. thaliana, IPK2 est une kinase d’inositol phosphates (InsP), des molécules plus ou moins phosphorylées impliquées dans la signalisation cellulaire et la réponse aux stress. Nous avons prouvé que KnIPK2 est capable de phosphoryler, mais aussi, de manière plus surprenante, de déphosphoryler certains InsP. Confirmant nos prédictions in silico, la S-nitrosation in vitro de KnIPK2 par du NO exogène semble inhiber son activité.En résumé, cette thèse a apporté des résultats pionniers sur la signalisation par le NO chez les algues. De plus, ce travail démontre l’implication du NO dans de nouvelles voies de signalisation, et suggère des pistes quant à l’étude de la résistance au stress salin
Nitric oxide (NO) is a major ubiquitous component of cell signaling, exerting its effects partly through protein S-nitrosation. This post-translational modification can impact protein activity, subcellular localization, and the ability to form protein complexes. Therefore, the characterization of S-nitrosated proteins is of great interest for elucidating NO functions. Previously, our laboratory provided provided evidence that land plants do not possess NO Synthase (NOS), the main NO-synthesizing enzyme in metazoans (Jeandroz et al., 2016). However, some algae species possess NOS-relative sequences, raising questions about their biochemistry and roles in these organisms. We focused on identifying S-nitrosated proteins in Klebsormidium nitens, a freshwater algal species which possess two NOS-relative sequences in its genome (Chatelain et al., 2022) and considered a model for studying plant adaptation to terrestrial life (Hori et al., 2014). We identified 43 candidate proteins with significantly higher levels of S-nitrosation under salt stress conditions. Orthology analysis was performed with Arabidopsis thaliana to determine the potential function of these proteins. We selected 3 proteins among them to study the role of their S-nitrosation in the salt stress response. These proteins are Protein Phosphatase 1 (PPH1), Histone Deacetylase 14 (HDA14), and Inositol Polyphosphate Multikinase 2 (IPK2).PPH1 is a crucial protein in terrestrial plant adaptation to light conditions. Characterization of KnPPH1 was initiated, but difficulties quickly arose, mainly due to poor annotation of its sequence in databases and difficulty in producing it in a heterologous system. HDA14 from A. thaliana and rice is a chloroplastic histone deacetylase, responsible for the deacetylation of proteins involved in photosynthesis, as well as the deacetylation of N-acetyl-serotonin into serotonin, precursors to melatonin synthesis. The sequence of KnHDA14 was verified, as well as its chloroplastic localization. We were able to produce it in a bacterial system and confirmed its deacetylase activity, which appears to be inhibited by NO. Finally, IPK2 in A. thaliana is an inositol phosphate (InsP) kinase. InsPs are more or less phosphorylated molecules involved in cell signaling and stress response. We have shown that KnIPK2 can phosphorylate but also, more surprisingly, can dephosphorylate certain InsPs. Confirming our in silico predictions, in vitro S-nitrosation of KnIPK2 by exogenous NO appears to inhibit its activity.In summary, this thesis has provided pioneering results on NO signaling in an algae. Additionally, this work demonstrates the involvement of NO in new signaling pathways, and suggests new ideas for studying salt stress resistance