Aquatic primary productivity mainly depends on pelagic phytoplankton. The globally abundant marine picocyanobacteria Prochlorococcus comprises a significant fraction of the photosynthetic biomass in most tropical, oligotrophic oceans. The Red Sea is an enclosed narrow body of water characterized by continuous solar irradiance, and negligible annual rainfall, in addition to elevated temperatures and salinity levels, which mimics a global warming scenario. Analysis of 16S rRNA sequences of bacterioplankton communities indicated the predominance of a high-light adapted ecotype (HL II) of Prochlorococcus at the surface of the Northern and Central Red Sea. To this end, we analyzed the distribution of Prochlorococcus at multiple depths within and below the euphotic zone in different regions of the Red Sea, using clone libraries of the 16S–23S rRNA internal transcribed spacer (ITS) region. Results indicated a high diversity of Prochlorococcus ecotypes at the 100 m depth in the water column and an unusual dominance of HL II-related sequences in deeper waters of the Red Sea. To further investigate the microdiversity of Prochlorococcus over a wider biogeographical scope, we used a 454-pyrosequencing approach to analyze rpoC1 gene pyrotags. Samples were collected from the surface of the water column to up to 500 m at 45 stations that span the Red Sea’s main basin from 4 north to south. Phylogenetic analysis of abundant rpoC1 OTUs revealed genotypes of recently discovered strains that belong to the high-light and lowlight clades. In addition, we used a rapid community-profiling tool (GraftM) and quantitatively analyzed rpoC1 gene abundance from 45 metagenomes to assess the Prochlorococcus community structure across vertical and horizontal physicochemical gradients. Results revealed the clustering of samples according to their depth and a strong influence on ecotypic distribution by temperature and oxygen levels. In efforts to better understand how the cells survive the unusual features of the Red Sea, a Prochlorococcus strain of the HL II adapted clade from the euphotic zone was cultured, enabling morphological analyses and growth rates measurements for the strain. In addition, we successfully sequenced and annotated the genome of the strain, which was then used for genomic comparison with other ecotypes. Interestingly, the set of unique genes identified in the draft genome included genes encoding proteins involved in salt tolerance mechanisms. The expression level and pattern of these genes in the Red Sea water column was explored through metatranscriptomic mapping and revealed their occurrence throughout, independent of the diel cycle. This led to the hypothesis that Prochlorococcus populations in the highly saline Red Sea are able to biosynthesize additional compatible solutes via several pathways to counterbalance the effects of salt stress. The results presented in this dissertation provide the first glimpse on how the environmental parameters of the Red Sea can affect the evolution, diversity and distribution patterns of Prochlorococcus ecotypes.

No description available.

Human ́s constant need for metals requires unsustainable mining and refining of metalore. As a result, highly contaminated wastewaters are discharged in the environmentcompromising the nearby habitat together with all its life forms. Microbial fuel cells arebioelectrochemical systems (BES’s) that use microorganisms to convert organic andinorganic matter, producing electricity as the final product. This technology has shownto have great potential for application for bioremediation of wastewaters. This thesisdescribes the gene expression and the taxonomical abundance of an acidophilic,electricity generating community that was used to treat mining wastewaters in amicrobial fuel cell. A complete metatranscriptomics analysis has been performed onduplicate MFC anode acidophilic microbial community generating electricity frominorganic sulfur compounds (ISC) oxidation at extremely low pH. The analysis showsthat the most expressed genus is Ferroplasma-like, the genus Acidithiobacillus-like isfollowing along with Sulfobacillus-like and Thermoplasma-like. Some of the generaexpressed show behaviours never described before suggesting that potentially, newspecies have been selected. The reactions of the sulfur pathway are regulated mostly bytwo genera: Acidithiobacillus-like during the disproportionation of tetrathionate, andFerroplasma-like by expressing the hdr gene that catalyses the reaction from elementalsulfur to sulfite, the sulfite is then converted to sulfate. The hdr gene has not previouslybeen found in F. acidarmanus-like suggesting that the specie might have been selectedfor this trait. Acidithiobacillus-like genus has a bigger role for the energy conservationand the electron transport in the sample, however the data are not sufficient to point outwhich gene has the major role in the process. The CO2 fixation in the chamber wasconsiderably low as a result from a significant carboxysomes production, bacterialcompartiments involved in the carbon dioxide fixation. The transcripts abundanceregarding the metal resistance genes have shown low expression suggesting that thecells were not under stress. This result is indicated by the synthesis of a transcriptionalrepressor protein that had prevented a significant production of metal resistanceenzymes. Likewise, the pH homeostasis plot does not show vast transcripts abundances,indicating that the cells were thriving under conditions not far from the optimum.

Considerando a dieta como um fator modulador do microbioma ruminal, neste trabalho objetivou-se investigar o impacto do bagaço da cana-de-açúcar sobre a composição e funcionalidade das espécies microbianas residentes no rúmen de carneiros (Ovis aries). Foram utilizados seis animais machos fistulados de O. aries, dos quais três foram alimentados com uma dieta composta por 70% de volumoso e 30% de concentrado (tratamento controle) e outros três animais alimentados com uma dieta similar a anterior, mas com 14% do volumoso substituído por bagaço de cana-de-açúcar (tratamento bagaço). O conteúdo ruminal (líquido e fibra) foram amostrados quinzenalmente durante 60 dias. A partir dessas amostras foram acessadas a estrutura e a composição da comunidade microbiana pela extração de DNA total e amplificação das regiões V3 e V6-V7 do gene 16S rRNA bacteriano e a região intergênica fúngica (ITS2). Além disso, foram feitas análises metagenômicas e metatranscriptômicas de comunidade microbianas enriquecidas em fibra ruminal para identificar enzimas lignocelulolíticas expressas. As frações líquida e fibrosa do conteúdo ruminal de O. aries revelaram uma comunidade bacteriana dominada principalmente por Bacteroidetes e Firmicutes ao longo de todo período experimental. Dois gêneros, Prevotella e Ruminococcus representaram 20% e 4% da comunidade bacteriana ruminal, respectivamente. Para a comunidade fúngica o filo Neocallimastigomycota representou 91% das sequências e os principais gêneros deste filo foram Piromyces, Neocallimastix, Orpinomyces, Anaeromyces, Caecomyces e Cyllamyces aderidos a fibra ruminal. O gênero Caecomyces, foi significativamente mais abundante na fibra ruminal de animais que se alimentaram de bagaço de cana-de açúcar. Além disso, foi observado um aumento significativo na frequência de enzimas como, por exemplo, 1,4-α-glucano, α-galactosidase, endo 1,4-β-xilanase, β- xilosidase, xilose isomerase, celobiose fosforilase e α-N-arabinofuranosidase no tratamento com bagaço de cana-de-açúcar. Considerando que a recuperação de enzimas a partir de comunidades microbianas naturalmente selecionadas para a degradação de biomassa é uma estratégia promissora para superar a atual ineficiência da ação enzimática na produção industrial de biocombustíveis, os resultados deste trabalho representam a possibilidade de aumentar a capacidade de recuperação ou descoberta de enzimas a partir de ruminantes, ou ainda, a possibilidade de manipular a estrutura do microbioma do rúmen para usá-lo como fonte de inóculo enriquecido em processos industriais de degradação de biomassa. / Considering the diet as a modulator of ruminal microbiome, this work aimed to investigate the impact of sugarcane bagasse on the composition and function of microbial species residents in the sheep (Ovis aries) rumen. Six cannulated male animals were used in the experiment, where three individuals were fed on a diet consisting of 70% forage and 30% concentrate (control treatment), and three were fed on a similar diet, but with sugarcane bagasse replacing 14% of the forage portion (bagasse treatment). The ruminal content (i.e., liquid and fiber) were sampled every two weeks during 60 days. From these samples, the structure and composition of the microbial community were assessed by total DNA extraction and amplification of V3 and V6-V7 regions of 16S rRNA gene from bacteria and the fungal intergenic region (ITS2). Furthermore, metagenomics and metatranscriptomics approaches were used to evaluate the enrichment of specific members of the microbial community in the ruminal fiber and genes related to lignocellulolytic enzymes. The liquid and fiber fractions of the O. aries rumen revealed a microbial community dominated mainly by Firmicutes and Bacteroidetes throughout the experimental period. The genera Prevotella and Ruminococcus accounted for 20% and 4% of the bacterial community of rumen, respectively. In the fungal community, the phylum Neocallimastigomycota accounted for 91% of sequences and its main genera adhered on the ruminal fiber were Piromyces, Neocallimastix, Orpinomyces, Anaeromyces, Caecomyces and Cyllamyces. The genus Caecomyces was significantly more abundant in the ruminal fiber in animals fed on sugarcane bagasse. Furthermore, there was a significant increase in the frequency of enzymes, such as α-1,4-glucan, α-galactosidase, endo- 1,4-β-xylanase, β-xylosidase, xylose isomerase, cellobiose phosphorylase and α- Narabinofuranosidase in the bagasse treatment. Considering that the recovery of enzymes from ecosystems naturally evolved for degradation of biomass is a promising strategy to overcome the current inefficient enzymatic action in industrial production of biofuels, the results of this study bring great possibilities to increase the discovery and or recovery of enzymes from ruminants, as well as the possibility of the ruminal microbiome structure manipulation to be used as source of an enriched inoculum for biomass degradation in industrial processes.

Considerando a dieta como um fator modulador do microbioma ruminal, neste trabalho objetivou-se investigar o impacto do bagaço da cana-de-açúcar sobre a composição e funcionalidade das espécies microbianas residentes no rúmen de carneiros (Ovis aries). Foram utilizados seis animais machos fistulados de O. aries, dos quais três foram alimentados com uma dieta composta por 70% de volumoso e 30% de concentrado (tratamento controle) e outros três animais alimentados com uma dieta similar a anterior, mas com 14% do volumoso substituído por bagaço de cana-de-açúcar (tratamento bagaço). O conteúdo ruminal (líquido e fibra) foram amostrados quinzenalmente durante 60 dias. A partir dessas amostras foram acessadas a estrutura e a composição da comunidade microbiana pela extração de DNA total e amplificação das regiões V3 e V6-V7 do gene 16S rRNA bacteriano e a região intergênica fúngica (ITS2). Além disso, foram feitas análises metagenômicas e metatranscriptômicas de comunidade microbianas enriquecidas em fibra ruminal para identificar enzimas lignocelulolíticas expressas. As frações líquida e fibrosa do conteúdo ruminal de O. aries revelaram uma comunidade bacteriana dominada principalmente por Bacteroidetes e Firmicutes ao longo de todo período experimental. Dois gêneros, Prevotella e Ruminococcus representaram 20% e 4% da comunidade bacteriana ruminal, respectivamente. Para a comunidade fúngica o filo Neocallimastigomycota representou 91% das sequências e os principais gêneros deste filo foram Piromyces, Neocallimastix, Orpinomyces, Anaeromyces, Caecomyces e Cyllamyces aderidos a fibra ruminal. O gênero Caecomyces, foi significativamente mais abundante na fibra ruminal de animais que se alimentaram de bagaço de cana-de açúcar. Além disso, foi observado um aumento significativo na frequência de enzimas como, por exemplo, 1,4-α-glucano, α-galactosidase, endo 1,4-β-xilanase, β- xilosidase, xilose isomerase, celobiose fosforilase e α-N-arabinofuranosidase no tratamento com bagaço de cana-de-açúcar. Considerando que a recuperação de enzimas a partir de comunidades microbianas naturalmente selecionadas para a degradação de biomassa é uma estratégia promissora para superar a atual ineficiência da ação enzimática na produção industrial de biocombustíveis, os resultados deste trabalho representam a possibilidade de aumentar a capacidade de recuperação ou descoberta de enzimas a partir de ruminantes, ou ainda, a possibilidade de manipular a estrutura do microbioma do rúmen para usá-lo como fonte de inóculo enriquecido em processos industriais de degradação de biomassa. / Considering the diet as a modulator of ruminal microbiome, this work aimed to investigate the impact of sugarcane bagasse on the composition and function of microbial species residents in the sheep (Ovis aries) rumen. Six cannulated male animals were used in the experiment, where three individuals were fed on a diet consisting of 70% forage and 30% concentrate (control treatment), and three were fed on a similar diet, but with sugarcane bagasse replacing 14% of the forage portion (bagasse treatment). The ruminal content (i.e., liquid and fiber) were sampled every two weeks during 60 days. From these samples, the structure and composition of the microbial community were assessed by total DNA extraction and amplification of V3 and V6-V7 regions of 16S rRNA gene from bacteria and the fungal intergenic region (ITS2). Furthermore, metagenomics and metatranscriptomics approaches were used to evaluate the enrichment of specific members of the microbial community in the ruminal fiber and genes related to lignocellulolytic enzymes. The liquid and fiber fractions of the O. aries rumen revealed a microbial community dominated mainly by Firmicutes and Bacteroidetes throughout the experimental period. The genera Prevotella and Ruminococcus accounted for 20% and 4% of the bacterial community of rumen, respectively. In the fungal community, the phylum Neocallimastigomycota accounted for 91% of sequences and its main genera adhered on the ruminal fiber were Piromyces, Neocallimastix, Orpinomyces, Anaeromyces, Caecomyces and Cyllamyces. The genus Caecomyces was significantly more abundant in the ruminal fiber in animals fed on sugarcane bagasse. Furthermore, there was a significant increase in the frequency of enzymes, such as α-1,4-glucan, α-galactosidase, endo- 1,4-β-xylanase, β-xylosidase, xylose isomerase, cellobiose phosphorylase and α- Narabinofuranosidase in the bagasse treatment. Considering that the recovery of enzymes from ecosystems naturally evolved for degradation of biomass is a promising strategy to overcome the current inefficient enzymatic action in industrial production of biofuels, the results of this study bring great possibilities to increase the discovery and or recovery of enzymes from ruminants, as well as the possibility of the ruminal microbiome structure manipulation to be used as source of an enriched inoculum for biomass degradation in industrial processes.

No description available.

No description available.

No description available.

Biofilme sind eine der widerstandsfähigsten Formen mikrobiellen Lebens. Ihr frühzeitiges Auftreten in der Erdgeschichte konnte durch Stromatolithfunde bewiesen werden. Heutige Biofilme und mikrobielle Matten bieten somit eine Möglichkeit wichtige Einblicke und Erkenntnisse über das erste Leben auf unserem Planeten zu geben. In dieser Arbeit wurden die prokaryotischen Lebensgemeinschaften von verschiedenen Ökosystemen mittels metagenomischer und metatranskriptomischer Methoden analysiert. Mithilfe von „Next-Generation Sequencing“ wurden 16S rRNA Genanalysen, metatranskriptomische Analysen und funktionsbasierte Durchmusterungen von Fosmid-Metagenombanken durchgeführt. Die bakterielle Zusammensetzung und Diversität von kalzifizierenden Biofilmen und dem unterliegenden Kalktuff des Frischwasserbachs Westerhöfer Bach wurden analysiert. Es konnte gezeigt werden, dass der Biofilm hauptsächlich von filamentösen Cyanobacteria, aeroben Vertretern aus allen Klassen der Proteobacteria und Chloroflexi bevölkert wurde. Die bakterielle Diversität nahm flussabwärts zu, was auf Änderungen der physikochemischen Parameter zurückgeführt wird. Aufgrund geringerer UV-Einstrahlung waren im Kalktuff mehr Proteobacteria als Cyanobacteria vorhanden. Des Weiteren gab es deutliche Unterschiede zwischen den relativen Abundanzen der gesamten und aktiven proteobakteriellen Klassen im Biofilm. Die aktiven Funktionen der Biofilm-Mikrobiota einer Westerhöfer Bach Probe wurden mittels metatranskriptomischer Methoden genauer analysiert. Die meisten Transkripte der mikrobiellen Biofilmgemeinschaft umfassten Gene der Photosynthese, des Proteinmetabolismus, des Kohlenstoffmetabolismus und der Zellatmung. Um das metagenomische Potential des Westerhöfer Bach Biofilms zu erschließen, wurden vier „large-insert“ Metagenombanken konstruiert. Funktionsbasierende Durchmusterungsverfahren führten zur Identifikation von fünf bisher unbekannten Genen, die für proteolytische Enzyme kodieren und einem Gen-Cluster, welches für cellulolytische Enzyme kodiert. Bei dem zweiten untersuchten Habitat handelt es sich um eine mikrobielle Matte des hypersalinen Lake 21 auf Kiritimati. Die Mikrobialith-bildende Matte besteht aus neun klar abgegrenzten, unterschiedlich gefärbten Lagen, welche separat auf ihre bakterielle und archaelle Zusammensetzung analysiert wurden. Anhand der prokaryotischen Zusammensetzung und dem Sauerstoff- und Lichtgradienten ergab sich eine Einteilung der mikrobiellen Matte in drei Zonen. Im Allgemeinen erhöhte sich die prokaryotische Diversität mit Tiefe der Matte, wohingegen das Redoxpotential und der pH-Wert sanken. Passend zu den hydrochemischen Daten änderte sich die prokaryotische Zusammensetzung von der photisch-oxischen Zone, welche aus halophilen, oxygenen und anoxygenen Phototrophen und aeroben Heterotrophen bestand, zu Sulfat-reduzierenden Bakterien (SRB), Fermentierern und potentiell Sulfat-reduzierenden Archaeen in der Übergangszone. In der anoxischen Zone konnten hauptsächlich SRB, Fermentierer, Ammonium-oxidierende Archaea und geringe Mengen methanogene Archaeen detektiert werden. Von den kenianischen Natronseen Bogoria, Sonachi, Elementeita und Magadi wurde die prokaryotische Zusammensetzung und Diversität von Boden-, Sediment-, Wasser-, und mikrobiellen Mattenproben analysiert. Hier zeigte sich, dass Boden- sowie Sedimentproben hauptsächlich von Proteobacteria, Gemmatimonadetes, Firmicutes, Actinobacteria, Acidobacteria und Bacteroidetes bevölkert wurden, wohingegen in den Wasserproben Cyanobacteria vorherrschten. Die Archaeen wurden überwiegend von unterschiedlichen Vertretern der Halobacteria repräsentiert. In den humiden Proben wurden außerdem methanogene Archaeen und Thaumarchaeota nachgewiesen. Letztlich wurde in dieser Arbeit die bakterielle Zusammensetzung des Biofilms und des dazugehörigen Planktons von mikrobiellen Brennstoffzellen (MBZ) untersucht. Der erzeugte Datensatz demonstrierte, dass die aktive und gesamte bakterielle Lebensgemeinschaft in den einzelnen Replikaten minimal variierte. Generell zeigte sich, dass stromproduzierende MBZ eine niedrigere bakterielle Diversität aufwiesen als nicht stromproduzierende MBZ. Des Weiteren zeigte die Analyse, dass bisher unkultivierte Vertreter der Spezies Geobacter und Clostridium mit der Stromproduktion verbunden waren.

Le sol est essentiel à toute société humaine notamment pour la production d'aliments. Son fonctionnement repose sur des réseaux d'interactions entre les éléments qui le composent et toute perturbation modifie ces réseaux. Les microorganismes eucaryotes représentent une composante importante de l'écosystème édaphique car ils sont impliqués dans des processus essentiels comme la régulation de populations de procaryotes. Mais paradoxalement, ils restent peu étudiés comparés aux bactéries notamment lorsqu'on s'intéresse aux cycles biogéochimiques autres que celui du carbone comme par exemple ceux des métaux. Suite à une pollution par des métaux, certains de ces microorganismes eucaryotes développent des mécanismes « de résistance » cellulaires. Dans ce contexte, le laboratoire d'accueil a isolé, directement à partir d'extraits d'ARN de sol, des gènes eucaryotes impliqués dans la résistance cellulaire au Cd. Ces nouveaux gènes forment une famille codant des protéines riches en cystéines dont les positions sont conservées au sein de cette famille. Mon projet de thèse a eu pour but de caractériser l'origine taxonomique et la fonction de cette famille de gènes. Dans un premier temps, la purification de cinq de ces protéines produites dans Escherichia coli et leurs caractérisations biochimiques par des méthodes spectrométriques ont permis de montrer que cette famille génique constitue une nouvelle famille de métallothionéines capables de chélater in vitro le Zn, le Cu et le Cd. Dans un second temps, une méthode de quantification par PCR quantitative de l'expression de ces gènes, extraits à partir de sol provenant de microcosmes, a été mise au point. Dans un troisième temps, nous avons tenté d'obtenir les régions génomiques bordant ces gènes environnementaux afin d'affilier les organismes qui les portent à un groupe taxonomique et d'analyser les régions promotrices de ces gènes par capture ciblée de gènes / Soil is essential to human societies, especially for food production. Its functioning relies on interaction networks sensitive to environmental alterations. Eukaryotic microorganisms are an important component of the soil ecosystem where they are involved in essential processes such as the regulation of prokaryotic populations. However, they remain poorly studied compared to bacteria, especially concerning their roles in biogeochemical cycles other than the carbon one such as metal cycles. In response to soil metal contamination, some of these eukaryotic microorganisms develop cellular "resistance" mechanisms. In this context, the host laboratory has previously isolated, directly from soils, eukaryotic genes able to confer Cd resistance. These genes form a family coding for cysteine-rich proteins whose cysteine positions are conserved within this sequences. My thesis project aimed at characterizing the function and taxonomic origin of this gene family. First, the purification of five of these proteins produced in Escherichia coli and their biochemical characterizations by spectrometric methods demonstrated that this gene family constitutes a new family of metallothioneins capable of chelating in vitro Zn, Cu and Cd. Some of these proteins are also able to confer Zn resistance when expressed in a sensitive yeast strain. In a second step, quantitative PCR methods for measuring expression levels of these genes in soil microcosms were developed. This will allow to evaluate the level of expression of these genes as a function of an increasing supply of exogenous metal. In a third step, we tried to obtain the genomic regions flanking these environmental genes in order to be able to associate the organisms from which they originate to a taxonomic group and to analyze the promoter regions of these genes using targeted capture