CO2 addition to increase biomass production and control microalgae species in high rate algal ponds treating wastewater

Challenges regarding microalgal cultivation need to be solved in order to enhance microalgae potential as a feedstock for biofuel, bioenergy, and bioproducts. The optimization of the operating strategy in high rate algal ponds treating wastewater still requires research on microalgal ecosystem response to variations in nutrients availability. For this reason, the aim of this study was to determine the effect of CO2 addition on microalgal population diversity and wastewater treatment performance. To this end, batch and continuous experiments were carried out in an experimental plant constituted by four high rate algal ponds (500 L each) treating urban wastewater with and without pH regulation. As expected, CO2 addition induced a significant increase in biomass concentration (between 66 and 100%). Moreover, a positive effect on microalgal biomass concentration was observed, reducing the effect of the variation in influent wastewater characteristics. Concerning the microalgal populations, the variation of inorganic carbon availability induced a shift in the dominant microalgae species. In spite of this, no variations were observed in terms of wastewater treatment efficiency. Taking together, this study highlighted the positive effect of CO2 addition to increase biomass production and control microalgae species in high rate algal ponds treating wastewater.Peer ReviewedPostprint (author's final draft

Examination of Gould's modified S1 (mS1) selective medium and Angle's non-selective medium for describing the diversity of Pseudomonas spp. in soil and root environments

Studies on the diversity of environmental culturable Pseudomonas populations are dependent on the isolation procedure. This procedure includes the use of selective media which may influence the recovery of strains and thus the diversity described. In this study, we assessed the use of two agar isolation media for describing the diversity of soil- and root-inhabiting Pseudomonas associated with the perennial grass Molinia coerulea. A total of 382 Pseudomonas strains were recovered on either non-selective Angle's medium, or on Gould's modified S1 (mS1) Pseudomonas-selective medium. Their diversity was assessed by restriction analysis of PCR (polymerase chain reaction)-amplified 16S-23S rDNA internal transcript spacer sequences. The comparison of mS1- and Angle-recovered populations showed that the use of mS1 selective medium led to an underestimation of both Pseudomonas counts and diversity, especially in the soil environmen

O trzech różnorodnych, ale zapomnianych dramatach K.H. Rostworowskiego

Numer wydany w 2017 r.This artice presents three dramas by Karol Hubert Rostworowski (1877-1938). The text concerns the problem of variety his dramas and values in: Judasz z Kariothu (1913), Miłosierdzie (1920) and Niespodzianka (1929). Talented Rostworowski was also an psychologist of the people

How elevated pCO2 modifies total and metabolically active bacterial communities in the rhizosphere of two perennial grasses grown under field conditions

The response of total (DNA-based analysis) and active (RNA-based analysis) bacterial communities to a pCO2 increase under field conditions was assessed using two perennial grasses: the nitrophilic Lolium perenne and the oligonitrophilic Molinia coerulea. PCR- and reverse transcriptase-PCR denaturing gradient gel electrophoresis analysis of 16S rRNA genes generated contrasting profiles. The pCO2 increase influenced mainly the active and root-associated component of the bacterial community. Bacterial groups responsive to the pCO2 increase were identified by sequencing of corresponding denaturing gradient gel electrophoresis bands. About 50% of retrieved sequences were affiliated to Proteobacteria. Our data suggest that Actinobacteria in soil and Myxococcales (Deltaproteobacteria) in root are stimulated under elevated pCO

Journée de formation Polar

En lien avec le rectorat de Lyon, le réseau des bibliothèques municipales de Lyon et la DRAC Auvergne-Rhône-Alpes, cette journée a pour but de sensibiliser les enseignants et bibliothécaires au polar et de leur donner des pistes pour amorcer un travail sur le genre avec les adultes et les enfants. Le programme de cette journée s’articule autour d’interventions d’éditeurs, auteurs, libraires et autres professionnels du livre qui viendront notamment présenter des nouveautés polar 2018-2019, apporter des éclairages sur les raisons du succès du polar nordique et aborderont les spécificités du roman policier jeunesse

Robust estimation of microbial diversity in theory and in practice

Quantifying diversity is of central importance for the study of structure, function and evolution of microbial communities. The estimation of microbial diversity has received renewed attention with the advent of large-scale metagenomic studies. Here, we consider what the diversity observed in a sample tells us about the diversity of the community being sampled. First, we argue that one cannot reliably estimate the absolute and relative number of microbial species present in a community without making unsupported assumptions about species abundance distributions. The reason for this is that sample data do not contain information about the number of rare species in the tail of species abundance distributions. We illustrate the difficulty in comparing species richness estimates by applying Chao's estimator of species richness to a set of in silico communities: they are ranked incorrectly in the presence of large numbers of rare species. Next, we extend our analysis to a general family of diversity metrics ("Hill diversities"), and construct lower and upper estimates of diversity values consistent with the sample data. The theory generalizes Chao's estimator, which we retrieve as the lower estimate of species richness. We show that Shannon and Simpson diversity can be robustly estimated for the in silico communities. We analyze nine metagenomic data sets from a wide range of environments, and show that our findings are relevant for empirically-sampled communities. Hence, we recommend the use of Shannon and Simpson diversity rather than species richness in efforts to quantify and compare microbial diversity.Comment: To be published in The ISME Journal. Main text: 16 pages, 5 figures. Supplement: 16 pages, 4 figure

The Genomes of the Fungal Plant Pathogens Cladosporium fulvum and Dothistroma septosporum Reveal Adaptation to Different Hosts and Lifestyles But Also Signatures of Common Ancestry.

We sequenced and compared the genomes of the Dothideomycete fungal plant pathogensCladosporium fulvum (Cfu) (syn. Passalora fulva) and Dothistroma septosporum (Dse) that are closely related phylogenetically, but have different lifestyles and hosts. Although both fungi grow extracellularly in close contact with host mesophyll cells, Cfu is a biotroph infecting tomato, while Dse is a hemibiotroph infecting pine. The genomes of these fungi have a similar set of genes (70% of gene content in both genomes are homologs), but differ significantly in size (Cfu \u3e61.1-Mb; Dse 31.2-Mb), which is mainly due to the difference in repeat content (47.2% in Cfu versus 3.2% in Dse). Recent adaptation to different lifestyles and hosts is suggested by diverged sets of genes. Cfu contains an α-tomatinase gene that we predict might be required for detoxification of tomatine, while this gene is absent in Dse. Many genes encoding secreted proteins are unique to each species and the repeat-rich areas in Cfu are enriched for these species-specific genes. In contrast, conserved genes suggest common host ancestry. Homologs of Cfu effector genes, including Ecp2 and Avr4, are present in Dse and induce a Cf-Ecp2- and Cf-4-mediated hypersensitive response, respectively. Strikingly, genes involved in production of the toxin dothistromin, a likely virulence factor for Dse, are conserved in Cfu, but their expression differs markedly with essentially no expression by Cfu in planta. Likewise, Cfu has a carbohydrate-degrading enzyme catalog that is more similar to that of necrotrophs or hemibiotrophs and a larger pectinolytic gene arsenal than Dse, but many of these genes are not expressed in planta or are pseudogenized. Overall, comparison of their genomes suggests that these closely related plant pathogens had a common ancestral host but since adapted to different hosts and lifestyles by a combination of differentiated gene content, pseudogenization, and gene regulation