Dr Christophe Lacroix

Professor

(Laboratory of Food Biotechnology, ETH Zurich)

Christophe Lacroix has been Full Professor for Food Biotechnology at the Institute of Food Science and Nutrition at the ETH Zurich since August 1, 2002.

Born in 1958 in Dijon, France, he studied Food Technology at the Ecole Nationale Supérieure des Industries Agricoles et Alimentaires in Massy, France, where received his food engineering degree in 1980. He then moved to Québec Canada where he completed a MSc and a PhD under the supervision of Professor F. Castaigne at Université Laval. From 1984 to 2002 he was Professor of Dairy Biotechnology in the Department of Food and Nutrition Sciences in Université Laval. He also lead the Dairy Research Centre STELA, from 1995 to 2002, and initiated in 1997 and was responsible until the end of 2002 for the Canadian Research Network on Lactic Acid Bacteria.

At the Laboratory for Food Biotechnology ETH Zurich he has extended his research area to develop fundamental knowledge on lactic acid and probiotic bacteria and selected metabolic activities with high potential, and their utilization in foods with improved quality, safety and benefits on consumer health. His research includes the development of technologies for production of lactic acid and probiotic bacteria, and control and modulation of physiology; the molecular characterization and utilization of specific metabolic activities of food bacteria and bifidobacteria; study on the complex intestinal microbiota with a new in vitro colonic system with immobilized cells; and modeling, control and optimization of complex food biotechnological processes such as cheese manufacture.

In vitro modeling of colonic fermentation, challenges and solutions

Abstract: A complex relationship occurs in the intestine between the gut microbiota, the diet, and the host. Different in vitro and in vivo strategies have been applied to elucidate mechanisms or functions of dietary compounds on the gut microbiota, health, and physiology of humans. In vitro gut fermentation modeling has gained momentum in recent years as a powerful strategy to isolate and investigate factors of the gut microbiota, independent of the host (1). In vitro models allow the application of a highly controlled environment and the study of mechanistic effects of dietary, microbial, drug and physiological factors on gut microbiota at levels that cannot be reached in in vivo setup. In vitro models are particularly well suited for screening, for example, prebiotics or probiotics for special functions in the gut, before moving to in vivo investigation s of effective conditions, while reducing in vivo animal testing. The human colon is inhabited by a multitude of multitude of mostly strict anaerobic microbes. A range of systems have been developed to model fermentation of the colon, which harbors the highest density of microbes: from simple anaerobic batch culture systems in flasks to multistage continuous flow models, which are different with respect to conditions and output (2). Selection of the most suitable model should be done carefully, considering their features and limits in relation with the scientific question addressed. In particular, most models do not reproduce the sessile state bacterial populations in the colon and do not reach bacterial density and microbial competition akin to the gut. To solve these limits we developed a process of fecal microbiota immobilization in polysaccharide beads. Different continuous intestinal fermentation models of the PolyFermS platform inoculated with fecal beads were set for mimicking healthy and diseased human gut microbiota (from young infant to elder) (3). PolyFermS models expanded to various configurations for different colon sections, allow the accurate comparison of treatments with a parallel control in blocked experiments (4). Features of the PolyFermS model platform, eventually combined with cellular models, will be illustrated in mechanistic studies and for cultivating and profiling gut microbiota.
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