A Simple In Vitro Gut Model for Studying the Interaction between Escherichia coli and the Intestinal Commensal Microbiota in Cecal Mucus.
A novel in vitro gut model was developed to better understand the interactions between Escherichia coli and the mouse cecal mucus commensal microbiota. The gut model is simple and inexpensive while providing an environment that largely replicates the nonadherent mucus layer of the mouse cecum. 16S rRNA gene profiling of the cecal microbial communities of streptomycin-treated mice colonized with E. coli MG1655 or E. coli Nissle 1917 and the gut model confirmed that the gut model properly reflected the community structure of the mouse intestine. Furthermore, the results from the in vitro gut model mimic the results of published in vivo competitive colonization experiments. The gut model is initiated by the colonization of streptomycin-treated mice, and then the community is serially transferred in microcentrifuge tubes in an anaerobic environment generated in anaerobe jars. The nutritional makeup of the cecum is simulated in the gut model by using a medium consisting of porcine mucin, mouse cecal mucus, HEPES-Hanks buffer (pH 7.2), Cleland's reagent, and agarose. Agarose was found to be essential for maintaining the stability of the microbial community in the gut model. The outcome of competitions between E. coli strains in the in vitro gut model is readily explained by the "restaurant hypothesis" of intestinal colonization. This simple model system potentially can be used to more fully understand how different members of the microbiota interact physically and metabolically during the colonization of the intestinal mucus layer.IMPORTANCE Both commensal and pathogenic strains of Escherichia coli appear to colonize the mammalian intestine by interacting physically and metabolically with other members of the microbiota in the mucus layer that overlays the cecal and colonic epithelium. However, the use of animal models and the complexity of the mammalian gut make it difficult to isolate experimental variables that might dictate the interactions between E. coli and other members of the microbiota, such as those that are critical for successful colonization. Here, we describe a simple and relatively inexpensive in vitro gut model that largely mimics in vivo conditions and therefore can facilitate the manipulation of experimental variables for studying the interactions of E. coli with the intestinal microbiota.
['Mokszycki|Matthew E|ME|', 'Leatham-Jensen|Mary|M|', 'Steffensen|Jon L|JL|', 'Zhang|Ying|Y|0000-0001-8759-0194', 'Krogfelt|Karen A|KA|0000-0001-7536-3453', 'Caldwell|Matthew E|ME|', 'Conway|Tyrrell|T|', 'Cohen|Paul S|PS|']
D000818:Animals D001419:Bacteria D002432:Cecum D004926:Escherichia coli D005243:Feces D000069196:Gastrointestinal Microbiome D007422:Intestines D008297:Male D051379:Mice D056265:Microbial Interactions D009093:Mucus D012336:RNA, Ribosomal, 16S D017421:Sequence Analysis D013307:Streptomycin
gut model Escherichia coli cecal mucus intestinal microbiota