Titanium Dioxide as Food Additive

Titanium dioxide is a white metal oxide used in many food categories as food additives to provide a whitening effect. If its use complies with the five specifications including synthesis pathway, crystallographic phase, purity, amount and innocuousness, all other parameters are not defined and were hardly documented. However, in the last 3 years, two studies have deeply characterized food-grade TiO2 and converged to the fact that the size distribution of food-grade TiO2 spans over the nanoparticle range (<100 nm) and the surface is not pure TiO2 but covered by phosphate and eventually silicon species or aluminium species, which modify the surface chemistry of these particles. Until now, this material was considered as safe. However, the toxicological studies later to the last re-evaluation by the European Food Safety Agency reveal some concerns due to the ability of TiO2 particles to alter the intestinal barrier. This reinforces the idea to go on reinforcing the risk assessment about food-grade TiO2

Contribution of plasmid-encoded peptidase S8 (PrtP) to adhesion and transit in the gut of Lactococcus lactis IBB477 strain

The ability of Lactococcus lactis to adhere to the intestinal mucosa can potentially prolong the contact with the host, and therefore favour its persistence in the gut. In the present study, the contribution of plasmid-encoded factors to the adhesive and transit properties of the L. lactis subsp. cremoris IBB477 strain was investigated. Plasmid-cured derivatives as well as deletion mutants were obtained and analysed. Adhesion tests were performed using non-coated polystyrene plates, plates coated with mucin or fibronectin and mucus-secreting HT29-MTX intestinal epithelial cells. The results indicate that two plasmids, pIBB477a and b, are involved in adhesion of the IBB477 strain. One of the genes localised on plasmid pIBB477b (AJ89_14230), which encodes cell wall-associated peptidase S8 (PrtP), mediates adhesion of the IBB477 strain to bare, mucin- and fibronectincoated polystyrene, as well as to HT29-MTX cells. Interactions between bacteria and mucus secreted by HT29- MTX cells were further investigated by fluorescent staining and confocal microscopy. Confocal images showed that IBB477 forms dense clusters embedded in secreted mucus. Finally, the ability of IBB477 strain and its ΔprtP deletion mutant to colonise the gastrointestinal tract of conventional C57Bl/6mice was determined. Both strains were present in the gut for up to 72 h. In summary, adhesion and persistence of IBB477 were analysed by in vitro and in vivo approaches, respectively. Our studies revealed that plasmidic genes encoding cell surface proteins are more involved in the adhesion of IBB477 strain than in the ability to confer a selective advantage in the gut

Enzyme recovery during gas/liquid two-phase flow microfiltration of enzyme/yeast mixtures

DOI:10.1002/bit.10415International audienc

Air-sparged microfiltration of enzyme/yeast mixtures: determination of optimal conditions for enzyme recovery

National audienc

Surface Proteins of Lactococcus lactis: Bacterial Resources for Muco-adhesion in the Gastrointestinal Tract

Food and probiotic bacteria, in particular lactic acid bacteria, are ingested in large amounts by humans and are part of the transient microbiota which is increasingly considered to be able to impact the resident microbiota and thus possibly the host health. The lactic acid bacterium Lactococcus lactis is extensively used in starter cultures to produce dairy fermented food. Also because of a generally recognized as safe status, L. lactis has been considered as a possible vehicle to deliver in vivo therapeutic molecules with anti-inflammatory properties in the gastrointestinal tract. One of the key factors that may favor health effects of beneficial bacteria to the host is their capacity to colonize transiently the gut, notably through close interactions with mucus, which covers and protects the intestinal epithelium. Several L. lactis strains have been shown to exhibit mucus-binding properties and bacterial surface proteins have been identified as key determinants of such capacity. In this review, we describe the different types of surface proteins found in L. lactis, with a special focus on mucus-binding proteins and pili. We also review the different approaches used to investigate the adhesion of L. lactis to mucus, and particularly to mucins, one of its major components, and we present how these approaches allowed revealing the role of surface proteins in muco-adhesion

Influence of a gas/liquid two-phase flow on the ultrafiltration and microfiltration performances: case of a ceramic flat sheet membrane

20 ref.International audienc

Application of gas/liquid two-phase flows during crossflow microfiltration of skimmed milk under constant transmembrane pressure conditions

International audienc

Application of gas/liquid two-phase flows during crossflow microfiltration of skimmed milk under constant transmembrane pressure conditions

International audienc

Application of gas/liquid two-phase flows during crossflow microfiltration of skimmed milk under constant transmembrane pressure conditions

International audienc