Development of a Six-Stage Culture System for Simulating the Gastrointestinal Microbiota of Weaned Infants

Abstract

The development of a six-stage culture system simulating the microbial community present in the intestine of weaned infants is described. Plate counts of selected fecal indicator-organisms revealed high concentrations in the culture liquid of the simulator and these data paralleled those in infant feces. The metabolic patterns of the microbiota present in the model and the infant feces, compared by means of BIOLOG, revealed similar carbon utilization pro les. A genetic ngerprinting by means of Denaturing Gradient Gel Electrophoresis generated a more complex banding pattern in the culture system than in infant feces. The three vessels representing the colon showed similar DGGE patterns, indicating a high stability of the dominant microbial species. Yet, high variability in terms of the dominant bacteria was observed in infant stools. The fermentative capacity of the in ×itro system, characterized by the concentration of volatile fatty acids and ammonium, was in accordance with the in ×i×o data. The enhanced production of propionate in ×itro is probably due to the high concentration of fermentable sugars in the culture medium and hence, a high fermentation rate. The elevated concentration of propionate, as well as valerate and caproate in ×itro suggests conditions favoring Megasphaera sp. fermentation. The data concerning microbial diversity and activity warrants further exploration of the in ×itro model as a tool for studying the impact of newly developed infant formulas, functional foods and pharmaceuticals on the gastrointestinal microbiota of infants.

Optimization of a yeast estrogen screen and its applicability to study the release of estrogenic isoflavones from a soygerm powder.

“…We determined the performance of the microbial community based on plate counts of selected indicator organisms and the fermentative capacity (19).…”

Stability and activity of an Enterobacter aerogenes-specific bacteriophage under simulated gastro-intestinal conditions

“…The R 2 value was greater than 0.99 for the standard curves and a slope of −3.67 was generated. Based on the standard curve, the exact number of E. aerogenes BE1/gfp cells in the DNA extracts could be determined Simulator of the human intestinal microbial ecosystem The SHIME reactor setup was based on the adult SHIME (Molly et al 1993;De Boever et al 2001). In brief, the SHIME was designed to maintain a microbial community that is representative of that in the human intestinal system.…”

“…The overall residence time of the last three reactors, simulating the large intestine, was 76 h. The temperature of the system was kept at 37°C by a thermostat and the system was kept anaerobic by flushing with N 2 for 15 min every day. Inoculum preparation and reactor start-up were as described by De Boever et al (2001).…”

“…In contrast, the human intestinal tract has been extensively studied and several in vitro systems have been developed (Molly et al 1993;Hack and Selenka 1996;Macfarlane et al 1998;Minekus et al 1999;De Boever et al 2001). In vitro models offer defined experimental conditions and easy sampling.…”

“…Also, the lack of ethical constraints when using in vitro model systems over human or animal subjects is an advantage. The simulation of the human intestinal microbial ecosys-tem (SHIME) is a five-stage reactor developed by Molly et al (1993) and optimized by De Boever et al (2001).…”