Effect of the gastrointestinal environment on pH homeostasis of Lactobacillus plantarum and Lactobacillus brevis cells as measured by real-time fluorescence ratio-imaging microscopy |
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| Institution: | 1. Department of Biology, Federal University of Lavras, 37.200-000 Lavras, MG, Brazil;2. Food Microbiology, Department of Food Science, Faculty of Science, University of Copenhagen, Denmark;1. Biology Department, University of Crete, Heraklion, Crete, Greece;2. Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology, Heraklion, Crete, Greece;1. Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, State Key Laboratory of Applied Organic chemistry, and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China;2. Institute of Polymer Materials, Qingdao University, Qingdao 266071, China;1. Heat Power Engineering Faculty, Nuclear Power Plants and Engineering Thermophysics Department, National Technical University of Ukraine “Kiev Polytechnic Institute” (NTUU “KPI”), 37, Peremogy Ave., Kiev 03056, Ukraine;2. National Polytechnic Institute of Mexico, Av. IPN s/n, Edificio 5, U.P.A.L.M., Col. Lindavista, Del. G.A.M., Mexico D.F. CP 07738, Mexico |
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| Abstract: | In the present work, an in vitro model of the gastrointestinal tract (GIT) was developed to obtain real-time observations of the pH homeostasis of single cells of probiotic Lactobacillus spp. strains as a measure of their physiological state. Changes in the intracellular pH (pHi) were determined using fluorescence ratio imaging microscopy (FRIM) for potential probiotic strains of Lactobacillus plantarum UFLA CH3 and Lactobacillus brevis UFLA FFC199. Heterogeneous populations were observed, with pHi values ranging from 6.5 to 7.5, 3.5 to 5.6 and 6.5 to 8.0 or higher during passage of saliva (pH 6.4), gastric (pH 3.5) and intestinal juices (pH 6.4), respectively. When nutrients were added to gastric juice, the isolate L. brevis significantly decreased its pHi closer to the extracellular pH (pHex) than in gastric juice without nutrients. This was not the case for L. plantarum.This study is the first to produce an in vitro GIT model enabling real-time monitoring of pH homeostasis of single cells in response to the wide range of pHex of the GIT. Furthermore, it was possible to observe the heterogeneous response of single cells. The technique can be used to determine the survival and physiological conditions of potential probiotics and other microorganisms during passage through the GIT. |
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| Keywords: | In vitro gastro-intestinal model FRIM Probiotic |
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