Jespersen, Lene

Moslehi Jenabian, Saloomeh

English

Copenhagen University Research Information System

u n i ve r s i t y  o f  co pe n h ag e n  Københavns UniversitetExpression of luxS gene involved in quorum sensing in Lactobacillus acidophilusNCFM after passage through an in vitro digestion modelMoslehi Jenabian, Saloomeh; Jespersen, LenePublication date:2010Document versionPeer reviewed versionCitation for published version (APA):Moslehi Jenabian, S., & Jespersen, L. (2010). Expression of luxS gene involved in quorum sensing inLactobacillus acidophilus NCFM after passage through an in vitro digestion model. Poster session presented at22nd international ICFMH symposium Food Micro 2010, København, Denmark.Download date: 02. Feb. 2020Results1. Survival of cells grown in MRS broth reduced significantly after 1 h incubation in the gastric juice (pH 3.5) and only 52% of cells survived after 2 h. Following 30 min incubation of cells in duodenal and bile juices a huge decrease in survival was observed (18%) and it reduced to 8% after 2 h (Fig. 2).2. Survival of cells grown in skim milk was significantly higher after 2 h incubation in gastric juice (73%) and during incubation in the duodenal and bile juices (48% after 2 h)  compared to the cells grown in MRS broth (Fig. 3).3. In cells grown in skim milk, the transcription of the luxS gene increased 3.0 fold after 30 min incubation in the gastric juice and reduced afterwards. The transcription increased again after incubation of cells in duodenal and bile juices. The highest transcription (3.4 fold) was observed after 2 h incubation in duodenal and bile juices (Fig. 4). Cells grown in MRS without protection of the food matrix were under severe stress during incubation at the harsh conditions of the digestion model, and therefore gene expression was highly unstable and could not be determined.ConclusionsThe luxS gene of L. acidophilus NCFM was up-regulated at the stress conditions of the in vitrodigestion model which shows that passage through the gastrointestinal tract has significant role in the induction of luxS gene in this probiotic, which has been shown to be involved in regulation of different behavior in probiotic lactobacilli. Thus this up-regulation might have significant effect in probiotic functionality and also cell-cell communication between microorganisms of gut ecosystem. In addition it was shown that the food matrix has an important role in the survival of the cells after stress conditions of the gastrointestinal tract. AcknowledgementsThis study is financed as a PhD grant  by the University of Copenhagen, Faculty of Life Sciences.ReferenceOomen AG, Rompelberg CJ, Bruil MA, Dobbe CJ, Pereboom DP, Sips AJ (2003). Development of an in vitro digestion model for estimating the bioaccessibility of soil contaminants. Archives of environmental contamination and toxicology 44:281-7.Expression of luxS gene involved in quorum sensing in Lactobacillus acidophilus NCFM after passage through an in vitro digestion modelIntroductionWithin recent years, there has been an increasing interest in discovering the beneficial effects of probiotics and the mechanisms by which probiotics interact with the host and the gut microbiota. One of the mechanisms that bacteria interact or communicate with each other is quorum sensing. Quorum sensing is cell-to-cell signalling through the production, secretion and detection of small signal molecules called autoinducers. The aim of the present study was to investigate the transcription of the luxS gene involved in quorum sensing in probiotic strain Lactobacillus acidophilusNCFM after passage through an in vitro digestion model, which could have effect on cell-to-cell communication between microorganisms of gut microbiota.Materials and MethodsStrain and Growth condition Overnight culture of L. acidophilus NCFM was inoculated (1.0%) in 50 ml MRS broth for 16 h at 37°C with the final pH of 4.2 and centrifuged and used for the experiments, or inoculated (10.0%) in 11.0% skim milk for 28 h at 37°C with final pH of 4.2 and 5 g of theculture was utilized. In vitro Digestion ModelAn in vitro digestion model of the upper gastrointestinal tract developed by Oomen et al. (2003) was used (Fig.1), including three compartments; mouth: saliva juice (6 ml, pH 6.5 for 5 min), stomach: gastric juice (12 ml, final pH 3.5 for 2 h) and small intestine: duodenal and bile juices (12 and 6 ml, respectively, final pH 6.5 for 2 h), incubation at 37°C with rotation head-over-heels. Samples were taken at t=0 and 30 min intervals for determination of survival and gene expression analysis using Taqman-based quantitative real-time PCR. The housekeeping gene 23S rRNA was used for normalisation.D E P A R T M E N T   O F   F O O D   S C I E N C EF A C U L T Y   O F   L I F E   S C I E N C E S U N I V E R S I T Y   O F   C O P E N H A G E NFig. 2 Survival of L. acidophilus NCFM cells grown in MRS after passage through the in vitro digestion modelFig. 3 Survival of L. acidophilus NCFM cells grown in skim milk after passage through the in vitro digestion modelFig. 4 Expression of the luxS gene in L. acidophilus NCFM cells grown in skim milk after passage through the in vitrodigestion modelFig. 1 Schematic diagram of the in vitro digestion modelSaloomeh Moslehi-Jenabian and Lene JespersenDepartment of Food Science, Food Microbiology, Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30 DK-1958 Frederiksberg C, Denmark; E-mail: smje@life.ku.dk, Tel: +45 35 33 10 390204060801001200 30 60 90 120 30 60 90 120Time (min)% SurvivalGastric Digestion Duodenal Digestion0204060801001200 30 60 90 120 30 60 90 120Time (min)% SurvivalGastric Digestion Duodenal Digestion0.00.51.01.52.02.53.03.54.04.50 30 60 90 120 30 60 90 120Time (min)Fold inductionGastric Digestion Duodenal Digestion1. Saliva (pH 6.5)2. Gastric Juice (pH 3.5)3. Duodenal + Bile Juice (pH 6.5)5 min2 h2 h

Expression of <em>luxS </em>gene involved in quorum sensing in <em>Lactobacillus acidophilus </em>NCFM after passage through an in vitro digestion model

https://curis.ku.dk/ws/files/32683915/Expression_of_luxS_gene.pdf

Expression of <em>luxS </em>gene involved in quorum sensing in <em>Lactobacillus acidophilus </em>NCFM after passage through an in vitro digestion model

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