Early adaptation to oxygen is key to the industrially important traits of Lactococcus lactis ssp. cremoris during milk fermentation

Background: Lactococcus lactis is the most used species in the dairy industry. Its ability to adapt to technological stresses, such as oxidative stress encountered during stirring in the first stages of the cheese-making process, is a key factor to measure its technological performance. This study aimed to understand the response to oxidative stress of Lactococcus lactis subsp. cremoris MG1363 at the transcriptional and metabolic levels in relation to acidification kinetics and growth conditions, especially at an early stage of growth. For those purposes, conditions of hyper-oxygenation were initially fixed for the fermentation. Results: Kinetics of growth and acidification were not affected by the presence of oxygen, indicating a high resistance to oxygen of the L. lactis MG1363 strain. Its resistance was explained by an efficient consumption of oxygen within the first 4 hours of culture, leading to a drop of the redox potential. The efficient consumption of oxygen by the L. lactis MG1363 strain was supported by a coherent and early adaptation to oxygen after 1 hour of culture at both gene expression and metabolic levels. In oxygen metabolism, the over-expression of all the genes of the nrd (ribonucleotide reductases) operon or fhu (ferrichrome ABC transports) genes was particularly significant. In carbon metabolism, the presence of oxygen led to an early shift at the gene level in the pyruvate pathway towards the acetate/2,3-butanediol pathway confirmed by the kinetics of metabolite production. Finally, the MG1363 strain was no longer able to consume oxygen in the stationary growth phase, leading to a drastic loss of culturability as a consequence of cumulative stresses and the absence of gene adaptation at this stage. Conclusions: Combining metabolic and transcriptomic profiling, together with oxygen consumption kinetics, yielded new insights into the whole genome adaptation of L. lactis to initial oxidative stress. An early and transitional adaptation to oxidative stress was revealed for L. lactis subsp. cremoris MG1363 in the presence of initially high levels of oxygen. This enables the cells to maintain key traits that are of great importance for industry, such as rapid acidification and reduction of the redox potential of the growth media

Differential influence of soluble dietary fibres on iIntestinal and hepatic carbohydrate response

Refined foods are commonly depleted in certain bioactive components that are abundant in ‘natural’ (plant) foods. Identification and addition of these ‘missing’ bioactives in the diet is, therefore, necessary to counteract the deleterious impact of convenience food. In this study, multiomics approaches were employed to assess the addition of the popular supplementary soluble dietary fibers inulin and psyllium, both in isolation and in combination with a refined animal feed. A 16S rRNA sequencing and 1H NMR metabolomic investigation revealed that, whilst inulin mediated an increase in Bifidobacteria, psyllium elicited a broader microbial shift, with Parasutterella and Akkermansia being increased and Enterorhabdus and Odoribacter decreased. Interestingly, the combination diet benefited from both inulin and psyllium related microbial changes. Psyllium mediated microbial changes correlated with a reduction of glucose (R −0.67, −0.73, respectively, p < 0.05) and type 2 diabetes associated metabolites: 3-methyl-2-oxovaleric acid (R −0.72, −0.78, respectively, p < 0.05), and citrulline (R −0.77, −0.71, respectively, p < 0.05). This was in line with intestinal and hepatic carbohydrate response (e.g., Slc2a2, Slc2a5, Khk and Fbp1) and hepatic lipogenesis (e.g., Srebf1 and Fasn), which were significantly reduced under psyllium addition. Although established in the liver, the intestinal response associated with psyllium was absent in the combination diet, placing greater significance upon the established microbial, and subsequent metabolomic, shift. Our results therefore highlight the heterogeneity that exists between distinct dietary fibers in the context of carbohydrate uptake and metabolism, and supports psyllium containing combination diets, for their ability to negate the impact of a refined diet

De la place marchande à la parcelle agricole. Ou quand le géographe enquête sur les relations villes-campagnes dans les Suds

Les campagnes des pays des Suds ont longtemps été étudiées au prisme de leur fonction productive. Toutefois, comme l’insécurité alimentaire ne relève pas seulement d’une question de production mais d’autres facteurs, tels que la vulnérabilité économique des populations (Sen, 1982) ou la circulation des denrées, Jean-Louis Chaléard a perçu les limites d’une analyse focalisée sur les rendements pour comprendre les défaillances de l’approvisionnement agricole des grandes villes. L’approvisionnement est défini comme « le processus d’acheminement des productions jusqu’à la ville et leur distribution à l’intérieur de l’espace urbain » (Douzant-Rosenfeld et Grandjean, 1996). Cette notion permet l’analyse conjointe de la production agricole et de sa commercialisation, mais plusieurs approches sont possibles. À une approche filière, centrée sur les produits et privilégiée par les agronomes, Jean-Louis Chaléard a préféré une approche innovante par les réseaux et les circuits marchands, menée au sein des marchés (Chaléard, 1996) : il s’est intéressé au commerçant et à l’agriculteur- marchand, ainsi qu’à leurs logiques propres, en tenant compte de leurs caractéristiques individuelles et collectives, de leur mobilité, des types de produits commercialisés, des modes de transport et des formes d’agricultures pratiquées

Getting relevant chemical and biological information from metabolomics data

National audienc

LC-MS metabolomic profiling of mesocarp tissue during tomato fruit development: comparison of different data pre-processing methods and analyses

International audienc

Metabolomic profiling of two tissues during tomato (Solanum lycopersicum) fruit development: cross-validation of LC, LC/MS and NMR approaches

National audienc

Can we trust untargeted metabolomics: results of the metabo-ring study

Can we trust untargeted metabolomics: results of the metabo-ring study. 2. African-European Conference on Chemometrics - Afrodata 201

Can we trust untargeted metabolomics: results of the metabo-ring study

Can we trust untargeted metabolomics: results of the metabo-ring study. 2. African-European Conference on Chemometrics - Afrodata 201