Sophie Landaud

• Professor
• Professor (Full) at French National Institute for Agriculture, Food, and Environment (INRAE)

Iron is involved in various microbial metabolisms and interactions and is an essential micronutrient for most microorganisms. This review focuses on the cheese ecosystem, in which iron is sparse (median concentration of 2.9 mg/kg based on a literature survey) and of limited bioavailability due to the presence of various metal-binding agents in the...

Domestication is an excellent model for studying adaptation processes, involving recent adaptation and diversification, convergence following adaptation to similar conditions, as well as degeneration of unused functions. Geotrichum candidum is a fungus used for cheese making and is also found in other environments such as soil and plants. By analyz...

Domestication is an excellent model for studying adaptation processes, constituting recent adaptation and diversification, as well as degeneration of unused functions. Geotrichum candidum is a fungus used for cheese-making and is also found in other environments such as soil and plants. By analyzing whole genome data from 98 strains, we found that...

Domestication is an excellent model for studying adaptation processes, constituting recent adaptation and diversification, as well as degeneration of unused functions. Geotrichum candidum is a fungus used for cheese making and is also found in other environments such as soil and plants. By analyzing whole genome data from 98 strains, we found that...

The aim of this study was to evaluate the capacity of an electronic nose, the NeOse Pro, to assess the alteration of two food matrixes of animal origin, beef and salmon. For each matrix, two types of samples were analyzed, natural samples and simplified “diluted” samples based on meat juice and agar. Samples were inoculated with specific spoilage o...

Studies of food microorganism domestication can provide important insight into adaptation mechanisms and lead to commercial applications. Penicillium roqueforti is a fungus with four genetically differentiated populations, two of which were independently domesticated for blue cheese-making, with the other two populations thriving in other environme...

Consumer demands for plant-based products have increased in recent years. However, their consumption is still limited due to the presence of off-flavor compounds, primarily beany and green notes, which are mainly associated with the presence of aldehydes, ketones, furans, and alcohols. To overcome this problem, fermentation is used as a lever to re...

The study of food microorganism domestication can bring important insights on adaptation mechanisms and have industrial applications. The Penicillium roqueforti mold is divided into four main populations, with two populations domesticated for blue-cheese making and two populations thriving in other environments. While most blue cheeses worldwide ar...

Ripening cultures containing fungi and bacteria are widely used in smear-ripened cheese production processes, but little is known about the biotic interactions of typical ripening microorganisms at the surface of cheese. We developed a lab-scale mini-cheese model to investigate the biotic interactions of a synthetic community that was composed of D...

Geotrichum candidum is a fungus-like yeast widely used as a starter culture for cheese ripening for its proteolytic and lipolytic activities and its contribution to the cheese flavours. The sequenced strain G. candidum CLIB 918 was isolated from cheese Pont-L'Evêque. This strain's ability to produce volatile compounds was compared to the ability of...

Smear-ripened cheeses develop a viscous, red-orange smear on their surfaces during ripening. For this reason, they are also called red-smear cheeses or bacterial surface-ripened cheeses. During the past decade, tremendous progress has been made in the understanding of the microbiology of the surface microbiota of these cheeses. This progress stems...

Cheese ripening is a complex biochemical process driven by microbial communities composed of both eukaryotes and prokaryotes. Surface-ripened cheeses are widely consumed all over the world and are appreciated for their characteristic flavor. Microbial community composition has been studied for a long time on surface-ripened cheeses, but only limite...

Sulfur metabolism is a central function of the cell. It has been extensively studied in the model yeast Saccharomyces cerevisiae. A comparative genomic study carried out across the hemiascomycetes clade has shown that S. cerevisiae displayed specificities not shared by the other yeast species. For instance, an O-acetylserine pathway was shown to be...

Organisms that can withstand anhydrobiosis possess the unique ability to temporarily and reversibly suspend their metabolism for the periods when they live in a dehydrated state. However, the mechanisms underlying the cell's ability to tolerate dehydration are far from being fully understood. The objective of this study was to highlight, for the fi...

Microbial communities living on cheese surfaces are composed of various bacteria, yeasts and molds that interact together, thus generating the typical sensory properties of a cheese. Physiological and genomic investigations have revealed important functions involved in the ability of microorganisms to establish themselves at the cheese surface. The...

Due to their importance in flavouring capacities (e.g. production of volatile sulphur compounds (VSCs)), their role in redox regulation (e.g. production of thiols) and their possible role in microbial interactions, sulphur compounds play a key role in traditional fermented products. A better knowledge and control of their microbial production is th...

Yarrowia lipolytica, located at the frontier of hemiascomycetous yeasts and fungi, is an excellent candidate for studies of metabolism evolution. This yeast, widely recognized for its technological applications, in particular produces volatile sulfur compounds (VSCs) that fully contribute to the flavor of smear cheese. We report here a relevant glo...

Staphylococcus equorum subsp. equorum is a member of the coagulase-negative staphylococcus group and is frequently isolated from fermented food products and from food-processing environments. It contributes to the formation of aroma compounds during the ripening of fermented foods, especially cheeses and sausages. Here, we report the draft genome s...

Corynebacterium casei is one of the most prevalent species present on the surfaces of smear-ripened cheeses, where it contributes to the production of the desired organoleptic properties. Here, we report the draft genome sequence of Corynebacterium casei UCMA 3821 to provide insights into its physiology.

Hemiascomycetes are separated by considerable evolutionary distances and, as a consequence, the mechanisms involved in sulfur metabolism in the extensively studied yeast, Saccharomyces cerevisiae, could be different from those of other species of the phylum. This is the first time that a global view of sulfur metabolism is reported in the biotechno...

Among the numerous compounds involved in cheese aroma, sulfur compounds are of particular interest because of their very powerful odors and low perception thresholds. Nevertheless, little attention has been focused until now on the possible presence of polyfunctional thiols in cheese, even if these compounds have been found to be associated with th...

Despite their importance as potent odors that contribute to the aroma of numerous cheeses, S-methyl thioesters formation pathways have not been fully established yet. In a first part of our work, we demonstrated that Brevibacterium antiquum and Brevibacterium aurantiacum could produce S-methyl thioesters using short-chain fatty acids or branched-ch...

In this study, we combined metabolic reconstruction, growth assays, and metabolome and transcriptome analyses to obtain a global view of the sulfur metabolic network and of the response to sulfur availability in Brevibacterium aurantiacum. In agreement with the growth of B. aurantiacum in the presence of sulfate and cystine, the metabolic reconstru...

The interactions that may occur between microorganisms in different ecosystems have not been adequately studied yet. We investigated yeast-bacterium interactions in a synthetic medium using different culture associations involving the yeast Yarrowia lipolytica 1E07 and two bacteria, Staphylococcus xylosus C2a and Lactococcus lactis LD61. The growth...

Multilocus sequence typing with nine selected genes is shown to be a promising new tool for accurate identifications of Brevibacteriaceae at the species level. A developed microarray also allows intraspecific diversity investigations of Brevibacterium aurantiacum showing that 13% to 15% of the genes of strain ATCC 9174 were absent or divergent in s...

With the view to investigate the presence of thiols in cheese, the use of different methods of preparation and extraction with an organomercuric compound ( p-hydroxymercuribenzoate) enabled the isolation of a new compound. The analysis of cheese extracts by gas chromatography coupled with pulse flame photometry, mass spectrometry, and olfactometry...

S. LANDAUD, P. PIQUEREL AND J. POURQUIÉ. 1995. More than 50 soil samples of various geographical origins have been screened for aerobic sporeformer bacteria displaying cellulolytic activity in the neutral pH range. Six independent clones were selected, which utilize and hydrolyse amorphous cellulose when grown at pH 8 on agarsolidified media. These...

The effect of cysteine on the ability of smear cheese-ripening bacteria (Brevibacterium linens and Arthrobacter spp) to produce volatile sulphur compounds (VSC) from methionine was studied. These bacteria were cultivated in a synthetic medium supplemented with various cysteine concentrations with or without methionine. Cultures with only cysteine s...

The formation of volatile sulfur compounds (VSC) in fermented food is a subject of interest. Such compounds are essential for the aroma of many food products like cheeses or fermented beverages, in which they can play an attractive or a repulsive role, depending on their identity and their concentration. VSC essentially arise from common sulfur-bea...

Production of volatile sulphur compounds (VSC) was assessed in culture media supplemented with L-methionine or L-methionine/L-cysteine mixtures, using five cheese-ripening yeasts: Debaryomyces hansenii DH47(8), Kluyveromyces lactis KL640, Geotrichum candidum GC77, Yarrowia lipolytica YL200 and Saccharomyces cerevisiae SC45(3). All five yeasts produ...

A practical adaptation of the methylene blue reaction for hydrogen sulfide quantification was developed to perform microbial selection. Closed plate flasks containing a zinc-agar layer above the liquid microbial culture are proposed as a trap system where the H(2)S can be retained and then quantified by the methylene blue reaction. Using this quant...

Cheese flavour is the result of complex biochemical transformations attributed to bacteria and yeasts grown in cheese curd. Volatile sulphur compounds (VSCs) are responsible for the characteristic aromatic notes of several cheeses, e.g., smear-ripened cheeses. The enzymatic degradation of L-methionine and subsequent formation of volatile sulfur com...

Tracing experiments were carried out to identify volatile and nonvolatile l-methionine degradation intermediates and end products in the yeast Geotrichum candidum and in the bacterium Brevibacterium linens, both of which are present in the surface flora of certain soft cheeses and contribute to the ripening reactions. Since the acid-sensitive bacte...

A dynamic model for diacetyl production and reduction was developed based on experimental data from 14 laboratory-scale (15-L) lager beer fermentations carried out in various conditions of temperature (10-16°C), top pressure (50-850 mbar), initial yeast concentration (5-20 million cells per milliliter) and initial wort gravity (1,036-1,099 g/L). Un...

The paper establishes a rigorous probabilistic framework for the reconciliation of apparently conflicting data from various physical and chemical measurements related to the key biological variables of alcoholic fermentation: the ethanol and the residual sugar concentrations. The analysis is carried out on a database consisting of 15 beer fermentat...

Advanced monitoring, fault detection, automatic control and optimisation of the beer fermentation process require on-line prediction and off-line simulation of key variables. Three dynamic models for the beer fermentation process are proposed and validated in laboratory scale: a model based on biological knowledge of the fermentation process, an em...

Temperature and top pressure are key factors for maintaining a consistent quality of lager beer. Their influence on yeast growth, CO2 production, final concentrations of fusel alcohol and ester and production kinetics was analysed under industrial conditions. Fermentations of 12°P lager wort were performed at 10°C or 16°C temperature and 1.05 bars...

This article presents a model of beer fermentation in terms of flavor component content. It describes the production of two higher alcohols (isoamyl alcohol and phenyl ethanol) and three esters (isoamyl acetate, ethyl acetate, and ethyl hexanoate) selected according to their organoleptic threshold values in beer, as well as the effects of operating...

A GC/MS method previously described for diacetyl was developed for the quantification of 2,3-pentanedione, and the derivatization procedure was modified for the determination of α-acetohydroxy acid. The reaction of 2,3-pentanedione with 4,5-dichloro-1,2-diaminobenzene produced 6,7-dichloro-2-methyl-3-ethylquinoxaline (DCMEQ), which was extracted wi...

Endoglucanase production by Bacillus circulons LS9 was increased through culture medium optimization, leading to 3,6 U/ml titers. Endoglucanase excretion, which is associated with other polysaccharide degrading activities, is not sporulation associated and not totally repressed by glucose or cellobiose. Moreover, the optimum pH for endoglucanase ac...

Different methods of sample preparation followed by extractions with p-hydroxymercuribenzoate (pHMB) were used to investigate the occurrence of thiol compounds in ripened cheeses. The analysis of cheese extracts by GC coupled with PFPD, MS and olfactometry detections enabled the identification of ethyl 2-mercaptopropionate (ET2MP) and ethyl 3-merca...