Olivier Gonçalves

French National Centre for Scientific Research | CNRS · GEPEA - UMR CNRS 6144

Microalgae provide valuable bio-components with economic and environmental benefits. The monitoring of microalgal production is mostly performed using different sensors and analytical methods that, although very powerful, are limited to qualified users. This study proposes an automated Raman spectroscopy-based sensor for the online monitoring of mi...

This study presents the development of a reliable method for quantifying C-phycocyanin. It was found that the spectrophotometric method commonly used for C-phycocyanin quantification tends to overestimate the actual amount of C-phycocyanin in Aphanizomenon flos-aquae (AFA) samples. The aim of this study was therefore to adapt the spectrophotometric...

The current study presents the development of a reliable method for the quantification of c-phycocyanin. It was found that the spectrophotometric method commonly used for c-phycocyanin quantification tends to overestimate the actual amount of c-phycocyanin in AFA samples. Thus, the aim of this study was to account for c-phycocyanin variation betwee...

The aim is to replace mineral waxes with vegetable fats as an organogel for candle manufacturing while keeping the same texture. The physico‐chemical characteristics of renewable vegetable raw materials differ from those of mineral waxes and consequently the structure of the blends in which they are used is modified. Their properties are measured a...

Nitrogen limitation and changing solar conditions are both known to affect triacylglycerol (TAG) production in microalgae. This study investigates the optimization of TAG production with a continuous nitrogen‐limited culture of Nannochloropsis gaditana in simulated day–night cycles (DNc). The effect of DNc was first investigated in nitrogen‐deprive...

In recent years diatoms have emerged as a major algal source for the production of bioactive compounds. Marine diatoms grow quickly and can store high amount of lipids. Unfortunately, they are little studied and underexploited resources. The current work deals with an original and rarely investigated source of diatoms: intertidal mudflats. It aims...

The SAVANE project (Station Autonome de Valorisation des Algues Naturelles Endogènes) is a winning project of the Bioeconomy and Environment call-for-projects (by the ADEME) to be realized from 2021 to 2024. Includes the participation of SARA and Aglosource societies, and GEPEA laboratory. The objective of the project is to build a semi-industrial...

The aim of this work is to track and optimize lipid recovery from Nannochloropsis gaditana in wet extraction operations. No significant differences in biomass concentration were found when disrupting microalgal suspensions of up to 30 g/L dry weight, but disruption efficiency differed depending on their physiological states. It took 5.8 min in a be...

Energy-storage metabolites such as neutral lipids and carbohydrates are valuable compounds for liquid biofuel production. The aim of this work is to elucidate the main biological responses of two algae species known for their effective energy-rich compound accumulation in nitrogen limitation and day–night cycles: Nannochloropsis gaditana, a seawate...

In this work, a new methodological approach, relying on the high specificity of enzymes in a complex mixture, was developed to estimate the composition of bioactive polysaccharides produced by microalgae, directly in algal cultures. The objective was to set up a protocol to target oligomers commonly known to be associated with exopolysaccharides’ (...

Microalgae are known for being capable to capture CO2 and turn them into profitable biomass in the efforts to mitigate climate change. Among the several uses of microalgae biomass & metabolites (e.g. cosmetics, nutrition, fertilizer, bioremediation) the microalgae biodiversity also includes several species that can be used as source of sugars and t...

The production of lipids by microalgae is widely studied, especially to find the best bioprocess operating conditions and optimize the productivity of the targeted product. In this context, being able to monitor online the evolution of the lipid concentration is a great advantage regarding the control and/or the optimization of the production. Yet,...

Microalgal biotechnology has gained considerable importance in recent decades. Applications range from simple biomass production for food and animal feed to valuable products for fuel, pharmaceuticals, health, biomolecules and materials relevant to nanotechnology. There are few reports of the exploration of wider microalgae biodiversity in the lite...

The sustainable production of lipids by microalgae is widely developed among the bioprocess community targeting various applications such as feed, food, health or bioenergy. The cultivation of microalgae needs dedicated systems with the optimal illumination geometry. Performing non-invasive online analyses on these bioprocesses is limited to few an...

The full text paper can be download for free until march 28th 2019 Following this link: https://authors.elsevier.com/a/1YWbD7sxn0RhZg Polysaccharides (PS) from photosynthetic microorganisms have gained interest over the last decade, due to very large variety of chemical structures and potential original physico-chemical and/or biological propertie...

The selection of suitable and indigenous microalgae species is a fundamental requirement in developing added-value bioactive compounds recoverable in the food, health, and cosmetics markets. In this work, an integrated screening approach was developed to characterize the lipid rate of 33 diatom species (including 15 species studied for the first ti...

Benchtop NMR spectrometers experience a great success for a wide range of applications. However, their performance is highly limited by peak overlaps. Emerging “pure‐shift NMR” (PS NMR) methods have been intensively used at high field to enhance the resolution by homodecoupling strategies. Here, different PS methods have been implemented on a compa...

Benchtop NMR devices are transportable, convenient, and affordable, unlike high‐field devices based on superconducting magnets. Such devices have opened numerous applications across a broad variety of scientific areas. This minireview focuses on the usefulness of benchtop nuclear magnetic resonance (NMR) for the monitoring of bioprocesses, highligh...

The work described in this paper investigates the behaviour of paraffin material under pressure. Compressibility has been widely described in the literature but the behaviour of paraffin materials under compression is not well known. This study intends to highlight the influence of particle size and shape of paraffin material on their compressibili...

The microorganisms responsible for spoilage do not belong to a single taxonomic group. Bacteria, molds and yeasts can be the cause of alterations. The variety of food microorganisms depends on different factors. The first is relative to the nature of the food, for example, the fact that fish products may be contaminated by water, vegetables by soil...

The microorganisms responsible for spoilage do not belong to a single taxonomic group. Bacteria, molds and yeasts can be the cause of alterations. The variety of food microorganisms depends on different factors. The first is relative to the nature of the food, for example, the fact that fish products may be contaminated by water, vegetables by soil...

An egg product is a complex matrix, mainly composed of water, proteins and lipids. It also contains carbohydrates, vitamins, minerals and many other compounds in varying concentrations. This chemical complexity makes it difficult to analyze, and most of the protocols are mainly concerned with the albumen and vitellus fractions, aside from the whole...

We developed an easy-to-use method for the routine analysis of the central metabolism using an affordable low-resolution GC–MS system run in SIM mode. The profiling approach was optimized for the derivatization protocol of some 60 targeted metabolites. The performance of two silylation reagents (MSTFA and BSTFA) that allowed the comprehensive deriv...

The mechanical characteristics of a paraffin–vegetable oil material and the compressive behavior of the powder stemming from this material were used to estimate the resistance of the compressed samples. The compressive behavior of powders under the low pressure range (1–2 MPa) applied in the candle industry was investigated in order to predict the...

An integrated screening approach was developed to assess the potential of the Botryococcus genus for the production of lipids for biofuel application (hydrocarbons and triacylglycerols). The strategy developed in this study permitted to rigorously measure mandatory parameters for the determination of strain performance – i.e. growth rate and oil co...

Two recent techniques based on chemical footprinting analysis, HRMAS NMR and FTIR spectroscopy, were tested on a brown macroalgal model. These powerful and easily-to-use techniques allowed us to discriminate Sargassum muticum specimens collected in five different countries along Atlantic coasts, from Portugal to Norway. HRMAS NMR and FT-IR permitte...

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 Bru...

Over the past years, the substitution of the classical biochemical quantification techniques by Fourier transform infrared (FTIR) spectroscopy has been widely studied on microalgae because of its tremendous application potential for bioprocess monitoring. In the present work, mandatory aspects that have never been approached by FTIR end-users worki...

In the field of composite materials, natural fibres appear to be a viable replacement for glass fibres. However, in humid conditions, strong hydrophilic behavior of such materials can lead to high level of moisture absorption. This feature can result in a structural modification of the fibres and a modification of their own mechanical properties as...

Two recent techniques based on chemical footprinting analysis, HRMAS NMR and FTIR spectroscopy, were tested on a brown macroalgal model. These powerful and easily-to-use techniques allowed us to discriminate Sargassum muticum specimens collected in five different countries along Atlantic coasts, from Portugal to Norway. HRMAS NMR and FTIR permitted...

Microalgae appear to be one of the most promising sustainable resources as alternative crops for the production of renewable transport fuel. The exploitation of this bioresource requires, however, a fine monitoring of the culture conditions, for example by using more relevant control variables than usual macroscopic indicators (biomass or pigment e...

Microalgae appear to be one of the most promising sustainable resources as alternative crops for the production of renewable transport fuel. The exploitation of this bioresource requires, however, a fine monitoring of the culture conditions, for example by using more relevant control variables than usual macroscopic indicators (biomass or pigment e...

In the field of composite materials, natural fibres appear to be a viable replacement for glass fibres. However, in humid conditions, strong hydrophilic behaviour of such materials can lead to their structural modification. Then, understanding moisture sorption mechanisms in these materials is an important issue for their efficient use. In this wor...

Adaptive metabolic behavior of photoautotrophic microorganisms toward genetic and environmental perturbations can be interpreted in a quantitative depiction of carbon flow through a biochemical reaction network using isotopic non-stationary (13) C-metabolic flux analysis (INST (13) C-MFA). To evaluate (13) C-metabolic flux maps for Chlamydomonas re...

High-quality annotation of microsporidian genomes is essential for understanding the biological processes that govern the development of these parasites. Here we present an improved structural annotation method using transcriptional DNA signals. We apply this method to re-annotate four previously annotated genomes, which allow us to detect annotati...

PAH composition detected in the contaminated soil S3. These data are proprietary data given by BioBasic Environnement and give the quantity of detected PAHs in mg/kg of dry soil in the contaminated soil studied.

Characterization of DNA signals implicated in ribosomal protein gene expression shared by microsporidian species. First column indicates product name, the five other columns present DNA sequences upstream the AUG start codon for E. cuniculi, A. locustae, E. bieneusi, A. algerae and N. ceranae. AAATTT-like motifs are colored in blue, CCC-like motifs...

SNR' profiles detected with microarray experiments and transcript numbers profiles detected with quantitative RT-PCR assays. SNR' profiles detected with microarray experiments (LEFT), and transcript copy number detected per ng of total RNA with quantitative RT-PCR assays (RIGHT) for eight genes: (A) phnA1a; (B) phnA2a; (C) ahdA1c; (D) ahdA2c; (E) b...

Upstream signals identification of genes coding for highly abundant proteins in E. cuniculi spores [28]. First column indicates ORF number, second column presents protein function, and third column the DNA upstream the AUG start codon. Adenine-rich regions are indicated in blue, CCC-like motifs in red and GGG-like motifs in green. The star characte...

Primers used for reverse transcription and quantitative real-time PCR assays. List of primers used for reverse transcription and subsequent quantitative real-time PCR assays. Amplification sizes are also given for each targeted gene.

Primer sets used for detecting catabolic genes involved in PAHs degradation and to generate the gene DNA matrix. The DNA matrix is used to build the standard curve for quantitative real-time PCR assays in strain EPA505. *: xylX and nahD are used to characterize complete sequences of bphC and ahdA1c. Nomenclature: M: A and C; R: A and G; W: A and T;...

Microorganisms display vast diversity, and each one has its own set of genes, cell components and metabolic reactions. To assess their huge unexploited metabolic potential in different ecosystems, we need high throughput tools, such as functional microarrays, that allow the simultaneous analysis of thousands of genes. However, most classical functi...

Abstract Background Microsporidia are obligate intracellular eukaryotic parasites with genomes ranging in size from 2.3 Mbp to more than 20 Mbp. The extremely small (2.9 Mbp) and highly compact (~1 gene/kb) genome of the human parasite Encephalitozoon cuniculi has been fully sequenced. The aim of this study was to characterize noncoding motifs that...

Biological data produced by high throughput technologies are becoming more and more abundant and are arousing many statistical questions. This paper addresses one of them; when gene expression data are jointly observed with other variables with the purpose of highlighting significant relationships between gene expression and these other variables....

Antarctic ecosystems are fascinating in their limited trophic complexity, with decomposition and nutrient cycling functions being dominated by microbial activities. Not only are Antarctic habitats exposed to extreme environmental conditions, the Antarctic Peninsula is also experiencing unequalled effects of global warming. Owing to their uniqueness...

We investigate an important issue of a meta-algorithm for selecting variables in the framework of microarray data. This wrapper method starts from any classification algorithm and weights each variable (i.e. gene) relative to its efficiency for classification. An optimization procedure is then inferred which exhibits important genes for the studied...

A proteinaceous inhibitor of alpha-amylase, Tendamistat, was evaluated as an immunogen to induce antibodies that mimic the enzyme activity and to investigate a new strategy to produce catalytic antibodies. Anti-Tendamistat polyclonal antibodies (pAbs) were shown to cross-react with acarbose, a strong carbohydrate inhibitor of alpha-amylases, and th...

The crystal structure of the complex of a catalytic antibody with its cationic hapten at 1.9-A resolution demonstrates that the hapten amidinium group is stabilized through an ionic pair interaction with the carboxylate of a combining-site residue. The location of this carboxylate allows it to act as a general base in an allylic rearrangement. When...

The catalytic antibody 4B2, which was generated against a substituted amidine 1, catalyses the allylic isomerization of beta, gamma-unsaturated ketones with an acceleration factor (k(cat)/k(uncat)) of 1.5x10(3). On the basis of the 'bait and switch' strategy, it was reasoned that the positively charged hapten could elicit, by charge complementarity...

Results are presented of an NMR microimaging study of the freezing of raw potato at 253 K. A fast radial imaging technique was used to obtain profiles along the sample radius. The profiles show that there is not a sharply defined ice front moving through the tissue, but rather a region where various fractions of ice and liquid water co-exist whose...