A novel pre-treatment for the methane production from microalgae by using N-methylmorpholine-N-oxide (NMMO)

The aim of this work was to study the effect of the solvent N-methylmorpholine-N-oxide (NMMO) to pre-treat Nannochloropsis oculata before the anaerobic digestion process. The results indicated that the pre-treatment affects the characteristics of the cell wall, which consequently becomes more susceptible to the microorganisms attack during anaerobic digestion. The methane production was increased by 43% after the pre-treatment, from 238±6mLCH4/gVS until 339±4mLCH4/gVS. On the contrary, the methane production from Chlorella vulgaris decreased after the pre-treatment from 251±4mLCH4/gVS to 231±3mLCH4/gVS. The failure on the pre-treatment was attributed to the particular characteristics of the substrate in consequence of a previous drying step.

Standardizing terms, definitions and concepts for describing and interpreting unwanted immunogenicity of biopharmaceuticals: recommendations of the Innovative Medicines Initiative ABIRISK consortium

Biopharmaceuticals (BPs) represent a rapidly growing class of approved and investigational drug therapies that is contributing significantly to advancing treatment in multiple disease areas, including inflammatory and autoimmune diseases, genetic deficiencies and cancer. Unfortunately, unwanted immunogenic responses to BPs, in particular those affecting clinical safety or efficacy, remain among the most common negative effects associated with this important class of drugs. To manage and reduce risk of unwanted immunogenicity, diverse communities of clinicians, pharmaceutical industry and academic scientists are involved in: interpretation and management of clinical and biological outcomes of BP immunogenicity, improvement of methods for describing, predicting and mitigating immunogenicity risk and elucidation of underlying causes. Collaboration and alignment of efforts across these communities is made difficult due to lack of agreement on concepts, practices and standardized terms and definitions related to immunogenicity. The Innovative Medicines Initiative (IMI; http://www.imi-europe.org), ABIRISK consortium [Anti-Biopharmaceutical (BP) Immunization Prediction and Clinical Relevance to Reduce the Risk; http://www.abirisk.eu] was formed by leading clinicians, academic scientists and EFPIA (European Federation of Pharmaceutical Industries and Associations) members to elucidate underlying causes, improve methods for immunogenicity prediction and mitigation and establish common definitions around terms and concepts related to immunogenicity. These efforts are expected to facilitate broader collaborations and lead to new guidelines for managing immunogenicity. To support alignment, an overview of concepts behind the set of key terms and definitions adopted to date by ABIRISK is provided herein along with a link to access and download the ABIRISK terms and definitions and provide comments (http://www.abirisk.eu/index_t_and_d.asp).

Development and validation of a screening procedure of microalgae for biodiesel production: application to the genus of marine microalgae Nannochloropsis

Nannochloropsis has emerged as a promising alga for biodiesel production. However, the genus consists of 6 species and hundreds of strains making strain selection a challenge. Furthermore, oil productivity is instrumental to economic viability of any algal strain for industrial production, which is dependent on growth rate and oil content. In most cases, these two parameters have been studied independently. Thus, the goal of this study is to provide a combined method for evaluating strain performance in specially designed photobioreactors together with an in-depth lipidomic analyses. The nine strains of Nannochloropsis tested showed considerable variations in productivity and lipidomics highlighting the importance of strain selection. Finally, Nannochloropsis gaditana CCMP527 and Nannochloropsis salina CCMP537 emerged as the two most promising strains, with an oil content of 37 and 27 dry wt% after 11-day nitrogen starvation, respectively, resulting in TAG productivity of 13×10(-3) and 18×10(-3) kg m(-3) d(-1), respectively.

Ammonium photo-production by heterocytous cyanobacteria: potentials and constraints

Over the last decades, production of microalgae and cyanobacteria has been developed for several applications, including novel foods, cosmetic ingredients and more recently biofuel. The sustainability of these promising developments can be hindered by some constraints, such as water and nutrient footprints. This review surveys data on N2-fixing cyanobacteria for biomass production and ways to induce and improve the excretion of ammonium within cultures under aerobic conditions. The nitrogenase complex is oxygen sensitive. Nevertheless, nitrogen fixation occurs under oxic conditions due to cyanobacteria-specific characteristics. For instance, in some cyanobacteria, the vegetative cell differentiation in heterocyts provides a well-adapted anaerobic microenvironment for nitrogenase protection. Therefore, cell cultures of oxygenic cyanobacteria have been grown in laboratory and pilot photobioreactors (Dasgupta et al., 2010; Fontes et al., 1987; Moreno et al., 2003; Nayak & Das, 2013). Biomass production under diazotrophic conditions has been shown to be controlled by environmental factors such as light intensity, temperature, aeration rate, and inorganic carbon concentration, also, more specifically, by the concentration of dissolved oxygen in the culture medium. Currently, there is little information regarding the production of extracellular ammonium by heterocytous cyanobacteria. This review compares the available data on maximum ammonium concentrations and analyses the specific rate production in cultures grown as free or immobilized filamentous cyanobacteria. Extracellular production of ammonium could be coupled, as suggested by recent research on non-diazotrophic cyanobacteria, to that of other high value metabolites. There is little information available regarding the possibility for using diazotrophic cyanobacteria as cellular factories may be in regard of the constraints due to nitrogen fixation.

Influence of light absorption rate by Nannochloropsis oculata on triglyceride production during nitrogen starvation

This study aims to understand the role of light transfer in triglyceride fatty-acid (TG-FA) cell content and productivity from microalgae during nitrogen starvation. Large amounts of TG-FA can be produced via nitrogen starvation of microalgae in photobioreactors exposed to intense light. First, spectral absorption and scattering cross-sections of N. oculata were measured at different times during nitrogen starvation. They were used to relate the mean volumetric rate of energy absorption (MVREA) per unit mass of microalgae to the TG-FA productivity and cell content. TG-FA productivity correlated with the MVREA and reached a maximum for MVREA of 13 μmol hν/gs. This indicated that TG-FA synthesis was limited by the photon absorption rate in the PBR. A minimum MVREA of 13 μmol hν/gs was also necessary at the onset of nitrogen starvation to trigger large accumulation of TG-FA in cells. These results will be instrumental in defining protocols for TG-FA production in scaled-up photobioreactors.

Rotational Hyperfine Structure of CD3I

The hyperfine structure of the ground state rotational spectrum of CD3I is remeasured with a greater accuracy and reanalyzed. The determinability of the hyperfine constants is discussed.

Influence of physical and chemical properties of HTSXT-FTIR samples on the quality of prediction models developed to determine absolute concentrations of total proteins, carbohydrates and triglycerides: a preliminary study on the determination of their absolute concentrations in fresh microalgal biomass

Absolute concentrations of total macromolecules (triglycerides, proteins and carbohydrates) in microorganisms can be rapidly measured by FTIR spectroscopy, but caution is needed to avoid non-specific experimental bias. Here, we assess the limits within which this approach can be used on model solutions of macromolecules of interest. We used the Bruker HTSXT-FTIR system. Our results show that the solid deposits obtained after the sampling procedure present physical and chemical properties that influence the quality of the absolute concentration prediction models (univariate and multivariate). The accuracy of the models was degraded by a factor of 2 or 3 outside the recommended concentration interval of 0.5-35 µg spot(-1). Change occurred notably in the sample hydrogen bond network, which could, however, be controlled using an internal probe (pseudohalide anion). We also demonstrate that for aqueous solutions, accurate prediction of total carbohydrate quantities (in glucose equivalent) could not be made unless a constant amount of protein was added to the model solution (BSA). The results of the prediction model for more complex solutions, here with two components: glucose and BSA, were very encouraging, suggesting that this FTIR approach could be used as a rapid quantification method for mixtures of molecules of interest, provided the limits of use of the HTSXT-FTIR method are precisely known and respected. This last finding opens the way to direct quantification of total molecules of interest in more complex matrices.

Investigation of fatty acids accumulation in Nannochloropsis oculata for biodiesel application

Lipids production of the marine microalga species Nannochloropsis oculata was deeply investigated by studying under continuous light the effects of different nitrogen starvation strategies in photobioreactors of various thicknesses. Operating parameters like incident photons flux density (PFD), initial nitrogen (progressive starvation strategy) or biomass concentrations (sudden starvation strategy) were examined, with a detailed analysis of their effects on the quality and production kinetics of total (TL) and triglycerides (TG). In addition to the already known effect of nitrogen starvation to trigger reserve lipids accumulation (mainly TG), it was demonstrated the relevance of the light received per cell affecting TG content and productivities, as well as fatty acids (FA) profiles. With appropriate optimization, N. oculata was confirmed as an interesting candidate for biodiesel application, with high FA accumulation (up to around 50%DW with 43%DW in TG-FA), high productivity (maximum 3.6×10(-3)kg(TG-FA)m(-2)d(-1)) and a TG-FA profile close to palm oil.