Method Article

An In Vitro Batch-culture Model to Estimate the Effects of Interventional Regimens on Human Fecal Microbiota

DOI:

10.3791/59524

⸱

July 31st, 2019

 ,  ,  ,  ,  ,  , 
1Department of Internal Medicine- Molecular Medicine, Wake Forest School of Medicine, 2Department of Microbiology and Immunology, Wake Forest School of Medicine, 3Department of Food Science and Technology, Isfahan University of Technology, 4Research Institute for Biotechnology and Bioengineering, College of Agriculture, Isfahan University of Technology, 5Department of Geriatrics and Gerontology, Wake Forest School of Medicine

In This Article

Summary

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This protocol describes an in vitro batch-culture fermentation system of human fecal microbiota, using inulin (a well-known prebiotic and one of the most widely studied microbiota modulators) to demonstrate the use of this system in estimating effects of specific interventions on fecal microbiota composition and metabolic activities.

Abstract

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The emerging role of the gut microbiome in several human diseases demands a breakthrough of new tools, techniques and technologies. Such improvements are needed to decipher the utilization of microbiome modulators for human health benefits. However, the large-scale screening and optimization of modulators to validate microbiome modulation and predict related health benefits may be practically difficult due to the need for large number of animals and/or human subjects. To this end, in vitro or ex vivo models can facilitate preliminary screening of microbiome modulators. Herein, it is optimized and demonstrated an ex vivo fecal microbiota culture system that can be used for examining the effects of various interventions of gut microbiome modulators including probiotics, prebiotics and other food ingredients, aside from nutraceuticals and drugs, on the diversity and composition of the human gut microbiota. Inulin, one of the most widely studied prebiotic compounds and microbiome modulators, is used as an example here to examine its effect on the healthy fecal microbiota composition and its metabolic activities, such as fecal pH and the fecal levels of organic acids including lactate and short-chain fatty acids (SCFAs). The protocol may be useful for studies aimed at estimating the effects of different interventions of modulators on fecal microbiota profiles and at predicting their health impacts.

Introduction

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The human microbiota is a complex community consisting of bacteria, archaea, viruses and eukaryotic microbes1, that inhabit the human body internally and externally. Recent evidences have established the fundamental role of the gut microbiota and the gut microbiome (the entire collection of microbes and their genes found in the human gastrointestinal tract) in various human diseases including obesity, diabetes, cardiovascular diseases, and cancer1,2,3. Additionally, the microorganisms living in our gut produce a wide spectrum of metabolites which signi....

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Protocol

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CAUTION: Consult the appropriate Material Safety Data Sheets and follow the instructions and guidelines for appropriate Biosafety Level 2 (BSL-2) training. Follow all the culturing steps as per the standard biosafety rules and use a BSL-2 cabinet using aseptic conditions. Furthermore, fecal samples from different models and human subjects may have potential risk of spreading microbial borne diseases. Immediately seek medical aid in the occurrence of any injury and infection. In addition, the use of human and animal stool samples should be approved through institutional ethical committees and must compliant with protocols to use samples and subject information.

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Results

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The protocol is used to demonstrate the effect of a specific prebiotic (i.e., inulin on the microbiota composition and metabolic activities in terms of changes in the fecal pH and the concentration of lactate and SCFAs in the feces of healthy human subjects over different time-points following treatment with inulin). The fecal pH, the fecal levels of lactate and SCFAs (Figure 1), and the microbiota composition (Figure 2 and

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Discussion

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The in vitro fecal slurry fermentation model presented here is a simple single-batch model to approximate the effects of different substrates and microbial strains (e.g., prebiotics and probiotics) on the composition of human fecal microbiota as well as its metabolic activities in terms of fecal pH and SCFAs levels. The results presented herein demonstrate that the inoculation of inulin decreases the fecal pH and significantly increases the levels of SCFAs and lactate in inulin-treated fecal specimen as compared to non-t.......

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Disclosures

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The authors have nothing to disclose.

Acknowledgements

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The authors gratefully acknowledge funding support from the Center for Diabetes, Obesity and Metabolism and the Clinical and Translational Science Center, the Wake Forest School of Medicine, the Department of Defense funding (Grant number: W81XWH-18-1-0118), the Kermit Glenn Phillips II Chair in Cardiovascular Medicine; the National Institutes of Health funded Claude D. Pepper Older Americans Center (funded by P30AG12232); R01AG18915; R01DK114224 and the Clinical and Translational Science Center (Clinical Research Unit, funded by UL1TR001420), is also thankfully acknowledged. We also thank the volunteers for providing fecal samples, and our other lab members for their....

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Materials

List of materials used in this article
NameCompanyCatalog NumberComments
Ammonium Bicarbonate (NH4HCO3)Sigma-Aldrich217255
Ammonium Sulfate (NH4)2SO4 TGIC2388Toxic
Calcium Chloride Dihydrate (CaCl2•2H2O)Sigma-AldrichC3306Irritating
Cobaltous Chloride Hexahydrate (CoCl2•6H2O)Sigma-Aldrich255599
Cupric Chloride Dihydrate (CuCl2•2H2O)Acros organics2063450000Toxic, Irritating
Cysteine-HClSigma-AldrichC121800
D-biotinSigma-AldrichB4501
D-Pantothenic acidAlfa AesarA16609
Disodium Ethylenediaminetetraacetate Dihydrate (Na2EDTA)Biorad1610729
DL-α-methylbutyrateSigma-AldrichW271918
Ferrous Sulfate Heptahydrate (FeSO4•7H2O)Sigma-AldrichF8263Toxic
Folic acidAlfa AesarJ62937
GlucoseSigma-AldrichG8270
HeminSigma-AldrichH9039
HepesAlfa AesarA14777
IsobutyrateAlfa AesarL04038
IsovalerateAlfa AesarA18642
Magnesium Chloride Hexahydrate (MgCl2•6H2O)Sigma-AldrichM8266
Manganese Chloride Tetrahydrate (MnCl2•4H2O)Sigma-Aldrich221279
Niacin (Nicotinic acid)Sigma-AldrichN4126
Nickel(Ii) Chloride Hexahydrate (NiCl2•6H2O)Alfa AesarA14366Toxic
N-valerateSigma-Aldrich240370
P-aminobenzoic acidMP China102569Toxic, Irritating
Phosphoric Acid (H3PO4)Sigma-AldrichP5811
Potassium Dihydrogen Phosphate (KH2PO4)Sigma-AldrichP5504
Potassium Hydrogen Phosphate (K2HPO4)Sigma-Aldrich1551128
PyridoxineAlfa AesarA12041
ResazurinSigma-AldrichR7017
RiboflavinAlfa AesarA11764
Sodium carbonate (Na2CO3)Sigma-Aldrich1613757
Sodium chloride (NaCl)Fisher BioReagents7647-14-5
Sodium hydroxide (NaOH)Fisher ChemicalsS320
Sodium Molybdate Dihydrate (Na2MoO4•2H2O)Acros organics206375000
Thiamine Hydrochloride (Thiamin-HCl)Acros organics148991000
TrypticaseBD Biosciences211921
Vitamin B12Sigma-AldrichV2876
Yeast extractSigma-Aldrich70161
Zinc Sulfate Heptahydrate (ZnSO4•7H2O)Sigma-AldrichZ0251
0.22 µm membrane filter
AMPure magnetic purification beadsAgencourt
Anaerobic chamber with incubatoreForma anaerobic system, Thermo Scientific, USA
Bottle filterCorning
Cheesecloth
Illumina MiSeq sequencerMiseq reagent kit v3
pH meter
Qiagen PowerFecal kitQiagen
Quantitative Insights into Microbial Ecology (QIIME) software
Qubit-3 fluorimeterInVitrogen
VortexThermoscientific
Waters-2695 Alliance HPLC systemWaters Corporation

References

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  1. Shreiner, A. B., Kao, J. Y., Young, V. B. The gut microbiome in health and in disease. Current Opinion in Gastroenterology. 31 (1), 69-75 (2015).
  2. Xu, Z., Knight, R. Dietary effects on human gut microbiome diversity. British Journal of Nutrition. 113, 1-5 (....

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Tags

Fecal Microbiota CultureIn Vitro Batch cultureGut Microbiome ModulatorsAnaerobic Chamber ConditionsShort chain Fatty Acid AnalysisMicrobiome Composition AnalysisFecal Inoculum PreparationInulin Prebiotic EffectsAseptic Technique ProtocolFecal pH Measurement

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