This study was funded by the National Nature Science Foundation of China (No. 31741109), the Hunan Natural Science Foundation (No. 2018JJ3200), and the construct program of applied characteristic discipline in Hunan University of Science and Engineering. We thank LetPub (www.letpub.com) for its linguistic assistance during the preparation of this manuscript.

This protocol follows the guidelines of the ethics committee of Hunan University of Science and Engineering (Hunan, China), and the Zhejiang Gongshang University (Zhejiang, China).
1. Preparation of bacteria
<ol>
<li>Preparation of bifidobacterium medium broth
<ol>
<li>Combine the following components in 950 mL of distilled water: meat extract, 5 g/L; yeast extract, 5 g/L; casein peptone, 10 g/L; soytone, 5 g/L; glucose, 10 g/L; K2HPO4, 2.04 g/L; MgSO4&#183;7...

<ol>
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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+psychology+of+the+human+brain-gut-microbiome+axis.">A psychology of the human brain-gut-microbiome axis.</a> Social and Personality Psychology Compass. 11 (4), e12309 (2017).</li><li>Arora, T., B&#228;ckhed, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+gut+microbiota+and+metabolic+disease:+current+understanding+and+future+perspectives.">The gut microbiota and metabolic disease: current understanding and future perspectives.</a> Journal of Internal Medicine. 280, 39-349 (2016).</li><li>Maurice, C., Haiser, H., Turnbaugh, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Xenobiotics+shape+the+physiology+and+gene+expression+of+the+active+human+gut+microbiome.">Xenobiotics shape the physiology and gene expression of the active human gut microbiome.</a> Cell. 152 (1-2), 39-50 (2013).</li><li>Carmody, R. 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D., Boers, S. A., van der Spek, P. J., Jansen, R., Hays, J. P., Stubbs, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Galaxy+mothur+Toolset+(GmT):+a+user-friendly+application+for+16S+rRNA+gene+sequencing+analysis+using+mothur.">Galaxy mothur Toolset (GmT): a user-friendly application for 16S rRNA gene sequencing analysis using mothur.</a> GigaScience. , (2018).</li><li>Wang, Q., Garrity, G. M., Tiedje, J. M., Cole, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Na&#239;ve+Bayesian+classifier+for+rapid+assignment+of+rRNA+sequences+into+the+new+bacterial+taxonomy.">Na&#239;ve Bayesian classifier for rapid assignment of rRNA sequences into the new bacterial taxonomy.</a> Applied and Environmental Microbiology. 73 (16), 5261-5267 (2007).</li><li>Schloss, P. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Introducing+mothur:+open-source,+platform-independent,+community-supported+software+for+describing+and+comparing+microbial+communities.">Introducing mothur: open-source, platform-independent, community-supported software for describing and comparing microbial communities.</a> Applied and Environmental Microbiology. 75 (23), 7537-7541 (2009).</li><li>Bai, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+study+on+the+in+vitro+effects+of+pseudomonas+aeruginosa+and+seaweed+alginates+on+human+gut+microbiota.">Comparative study on the in vitro effects of pseudomonas aeruginosa and seaweed alginates on human gut microbiota.</a> Plos One. 12 (2), e0171576 (2017).</li><li>Zhang, Z., Xie, J., Zhang, F., Linhardt, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thin-layer+chromatography+for+the+analysis+of+glycosaminoglycan+oligosaccharides.">Thin-layer chromatography for the analysis of glycosaminoglycan oligosaccharides.</a> Analytical Biochemistry. 371, 118-120 (2007).</li><li>Simon, J. C., Marchesi, J. R., Mougel, C., Selosse, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Host-microbiota+interactions:+from+holobiont+theory+to+analysis.">Host-microbiota interactions: from holobiont theory to analysis.</a> Microbiome. 7 (5), (2019).</li><li>Postler, T. S., Ghosh, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+the+Holobiont:+how+microbial+metabolites+affect+human+health+and+shape+the+immune+system.">Understanding the Holobiont: how microbial metabolites affect human health and shape the immune system.</a> Cell Metabolism. 26 (1), 110-130 (2017).</li><li>Kramer, P., Bressan, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Humans+as+superorganisms:+how+microbes,+viruses,+imprinted+genes,+and+other+selfish+entities+shape+our+behavior.">Humans as superorganisms: how microbes, viruses, imprinted genes, and other selfish entities shape our behavior.</a> Perspectives on Psychological Science. 10 (4), 464-481 (2015).</li><li>Malfertheiner, P., Nardone, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gut+microbiota:+the+forgotten+organ.">Gut microbiota: the forgotten organ.</a> Digestive Diseases. 29 (6), (2011).</li><li>Andoh, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+gut+microbiota+is+a+new+organ+in+our+body.">The gut microbiota is a new organ in our body.</a> The Japanese journal of Gastro-Enterology. 112 (11), 1939-1946 (2015).</li><li>Mika, A., Van, W. T., Gonz&#225;lez, A., Herrera, J. J., Knight, R., Fleshner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exercise+is+more+effective+at+altering+gut+microbial+composition+and+producing+stable+changes+in+lean+mass+in+juvenile+versus+adult+male+f344+rats.">Exercise is more effective at altering gut microbial composition and producing stable changes in lean mass in juvenile versus adult male f344 rats.</a> PLoS One. 10 (5), e0125889 (2015).</li><li>Hugenholtz, F., de Vos, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+models+for+human+intestinal+microbiota+research:+a+critical+evaluation.">Mouse models for human intestinal microbiota research: a critical evaluation.</a> Cellular and Molecular Life Sciences. 75 (1), 149-160 (2018).</li><li>Takagi, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+single-batch+fermentation+system+to+simulate+human+colonic+microbiota+for+high-throughput+evaluation+of+prebiotics.">A single-batch fermentation system to simulate human colonic microbiota for high-throughput evaluation of prebiotics.</a> PLoS One. 11 (8), e0160533 (2016).</li><li>Ning, T., Gong, X., Xie, L., Ma, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gut+microbiota+analysis+in+rats+with+methamphetamine-induced+conditioned+place+preference.">Gut microbiota analysis in rats with methamphetamine-induced conditioned place preference.</a> Frontiers in Microbiology. 8 (1), 1620 (2017).</li></ol>

Significant progress has been made towards understanding human gut microbiota composition and activities over the last decade. As a consequence of these studies, the holobiont concept has emerged, which represents the interactions between hosts and associated microbial communities, such as in between humans and their gut microbiota19,20. Furthermore, humans are even now regarded as superorganisms21, wherein the gut microbiota have been rec...

Gut microbiota play an important role in the functioning of human intestines and in host health. Consequently, gut microbiota have recently become an important target for disease prevention and therapy1. Moreover, gut bacteria interact with host intestinal cells and regulate fundamental host processes, including metabolic activities, nutrient availabilities, immune system modulation, and even brain function and decision-making2,3. Endobiotics have considerable potential to influence the bacterial composition and diversity of gut microbiota. Thus, interactions between endobiotics and human gut microbiota have attracted increasing research attention4,5,6,7,8,9.
It is difficult to evaluate interactions between endobiotics and human gut microbiota in vivo due to bioethics and economic constraints. For example, experiments investigating the interactions between endobiotics and human gut microbiota cannot be performed without permission of the Food and Drug Administration, and recruitment of volunteers is expensive. Consequently, animal models are often used for such investigations. However, the use of animal models is limited due to different microbiota compositions and diversity in animal- vs. human-associated communities. An alternative in vitro method to explore the interactions between endobiotics and human gut microbiota is through the use of batch culture experiments.
Exopolysaccharides (EPSs) are prebiotics that significantly contribute to the maintenance of human health10. Distinct EPSs that consist of different monosaccharide compositions and structures can exhibit distinct functions. Previous analyses have determined the composition of Bif EPSs, which are the representative xenobiotic targeted in the current study11. However, host-associated metabolic effects have not been considered with regard to EPS composition and diversity.
The protocol described here uses the fecal microbiota from 12 volunteers to ferment Bif EPSs. Thin-layer chromatography (TLC), 16S rRNA gene high-throughput sequencing, and gas chromatography (GC) are then used in combination to investigate the interactions between EPSs and human gut microbiota. Distinct advantages of this protocol compared to in vivo experiments are its low cost and avoidance of interfering effects from the host&#x2019;s metabolism. Furthermore, the described protocol can be used in other studies that investigate interactions between endobiotics and human gut microbiota.

<table>
	<tbody>
		<tr>
			<td>0.22 &#181;m membrane filters</td>
			<td>Millipore</td>
			<td>SLGP033RB</td>
			<td>Use to filter samples</td>
		</tr>
		<tr>
			<td>0.4-mm Sieve</td>
			<td>Thermo Fischer</td>
			<td>308080-99-1</td>
			<td>Use to prepare human fecal samples</td>
		</tr>
		<tr>
			<td>5-bromo-4-chloro-3-indolyl &#946;-D-galactopyranoside (X-Gal)</td>
			<td>Solarbio</td>
			<td>X1010</td>
			<td>Use to prepare color plate</td>
		</tr>
		<tr>
			<td>Acetic</td>
			<td>Sigma-Aldrich</td>
			<td>71251</td>
			<td>Standard sample for SCFA</td>
		</tr>
		<tr>
			<td>Agar</td>
			<td>Solarbio</td>
			<td>YZ-1012214</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Anaerobic chamber</td>
			<td>Electrotek&#160;</td>
			<td>AW 400SG</td>
			<td>Bacteria culture and fermentation</td>
		</tr>
		<tr>
			<td>Autoclave</td>
			<td>SANYO</td>
			<td>MLS-3750</td>
			<td>Use to autoclave</td>
		</tr>
		<tr>
			<td>Bacto soytone</td>
			<td>Sigma-Aldrich</td>
			<td>70178</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Baking oven</td>
			<td>Shanghai Yiheng Scientific Instruments Co., Ltd</td>
			<td>DHG-9240A</td>
			<td>Use to heat and bake</td>
		</tr>
		<tr>
			<td>Beef Extract</td>
			<td>Solarbio</td>
			<td>G8270</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Bifidobacterium longum Reuter</td>
			<td>ATCC</td>
			<td>ATCC&#174; 51870&#8482;</td>
			<td>Bacteria</td>
		</tr>
		<tr>
			<td>Bile Salts</td>
			<td>Solarbio</td>
			<td>YZ-1071304</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Butyric</td>
			<td>Sigma-Aldrich</td>
			<td>19215</td>
			<td>Standard sample for SCFA</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Solarbio</td>
			<td>C7250</td>
			<td>Salt solution of medium</td>
		</tr>
		<tr>
			<td>Capillary column</td>
			<td>SHIMADZU-GL</td>
			<td>InertCap FFAP (0.25 mm &#215; 30 m &#215; 0.25 &#956;m)</td>
			<td>Used to SCFA detection</td>
		</tr>
		<tr>
			<td>Casein Peptone</td>
			<td>Sigma-Aldrich</td>
			<td>39396</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Thermo Scientific</td>
			<td>Sorvall ST 8</td>
			<td>Use for centrifugation</td>
		</tr>
		<tr>
			<td>CoSO4.7H2O</td>
			<td>Solarbio</td>
			<td>C7490</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>CuSO4.5H2O</td>
			<td>Solarbio</td>
			<td>203165</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Cysteine-HCl</td>
			<td>Solarbio</td>
			<td>L1550</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma-Aldrich</td>
			<td>E7023</td>
			<td>Use to prepare vitamin K1</td>
		</tr>
		<tr>
			<td>FeSO4.7H2O</td>
			<td>Solarbio</td>
			<td>YZ-111614</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Formic Acid</td>
			<td>Sigma-Aldrich</td>
			<td>399388</td>
			<td>Used to TLC</td>
		</tr>
		<tr>
			<td>Gas chromatography</td>
			<td>Shimadzu Corporation</td>
			<td>GC-2010 Plus</td>
			<td>Used to SCFA detection</td>
		</tr>
		<tr>
			<td>Glass beaker</td>
			<td>Fisher Scientific</td>
			<td>FB10050</td>
			<td>Used for slurry preparation</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Solarbio</td>
			<td>G8760</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Haemin</td>
			<td>Solarbio</td>
			<td>H8130</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>HCl</td>
			<td>Sigma-Aldrich</td>
			<td>30721</td>
			<td>Basic solution used to adjust the pH of the buffers</td>
		</tr>
		<tr>
			<td>Isobutyric</td>
			<td>Sigma-Aldrich</td>
			<td>46935-U</td>
			<td>Standard sample for SCFA</td>
		</tr>
		<tr>
			<td>Isovaleric Acids</td>
			<td>Sigma-Aldrich</td>
			<td>129542</td>
			<td>Standard sample for SCFA</td>
		</tr>
		<tr>
			<td>K2HPO4</td>
			<td>Solarbio</td>
			<td>D9880</td>
			<td>Salt solution of medium</td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Solarbio</td>
			<td>P9921</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Solarbio</td>
			<td>P7392</td>
			<td>Salt solution of medium</td>
		</tr>
		<tr>
			<td>LiCl.3H2O</td>
			<td>Solarbio</td>
			<td>C8380</td>
			<td>Use to prepare color plate</td>
		</tr>
		<tr>
			<td>Meat Extract</td>
			<td>Sigma-Aldrich-Aldrich</td>
			<td>70164</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Metaphosphoric Acid</td>
			<td>Sigma-Aldrich</td>
			<td>B7350</td>
			<td>Standard sample for SCFA</td>
		</tr>
		<tr>
			<td>MgCl2.6H2O</td>
			<td>Solarbio</td>
			<td>M8160</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>MgSO4.7H2O</td>
			<td>Solarbio</td>
			<td>M8300</td>
			<td>Salt solution of medium</td>
		</tr>
		<tr>
			<td>MISEQ</td>
			<td>Illumina</td>
			<td>MiSeq 300PE system</td>
			<td>DNA sequencing</td>
		</tr>
		<tr>
			<td>MnSO4.H20</td>
			<td>Sigma-Aldrich</td>
			<td>M8179</td>
			<td>Salt solution of medium</td>
		</tr>
		<tr>
			<td>Mupirocin</td>
			<td>Solarbio</td>
			<td>YZ-1448901</td>
			<td>Antibiotic</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Solarbio</td>
			<td>YZ-100376</td>
			<td>Salt solution of medium</td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>Sigma-Aldrich</td>
			<td>792519</td>
			<td>Salt solution of medium</td>
		</tr>
		<tr>
			<td>NanoDrop ND-2000</td>
			<td>NanoDrop Technologies</td>
			<td>ND-2000</td>
			<td>Determine DNA concentrations</td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td>Sigma-Aldrich</td>
			<td>30620</td>
			<td>Basic solution used to adjust the pH of the buffers</td>
		</tr>
		<tr>
			<td>n-butanol</td>
			<td>ChemSpider</td>
			<td>71-36-3</td>
			<td>Used to TLC</td>
		</tr>
		<tr>
			<td>NiCl2</td>
			<td>Solarbio</td>
			<td>746460</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Orcinol</td>
			<td>Sigma-Aldrich</td>
			<td>447420</td>
			<td>Used to prepare orcinol reagents</td>
		</tr>
		<tr>
			<td>Propionic</td>
			<td>Sigma-Aldrich</td>
			<td>94425</td>
			<td>Standard sample for SCFA</td>
		</tr>
		<tr>
			<td>QIAamp DNA Stool Mini Kit</td>
			<td>QIAGEN</td>
			<td>51504</td>
			<td>Extract bacterial genomic DNA</td>
		</tr>
		<tr>
			<td>Ready-to-use PBS powder</td>
			<td>Sangon Biotech (Shanghai) Co., Ltd.</td>
			<td>A610100-0001</td>
			<td>Used to prepare the lipid suspension</td>
		</tr>
		<tr>
			<td>Resazurin</td>
			<td>Solarbio</td>
			<td>R8150</td>
			<td>Anaerobic Equipment</td>
		</tr>
		<tr>
			<td>Speed Vacuum Concentrator</td>
			<td>LABCONCO</td>
			<td>CentriVap</td>
			<td>Use to prepare EPSs</td>
		</tr>
		<tr>
			<td>Starch</td>
			<td>Solarbio</td>
			<td>YZ-140602</td>
			<td>Use to the carbon source</td>
		</tr>
		<tr>
			<td>Sulfuric Acid</td>
			<td>Sigma-Aldrich</td>
			<td>150692</td>
			<td>Used to prepare orcinol reagents</td>
		</tr>
		<tr>
			<td>T100 PCR</td>
			<td>BIO-RAD</td>
			<td>1861096</td>
			<td>PCR amplification</td>
		</tr>
		<tr>
			<td>TLC aluminium sheets</td>
			<td>MerckMillipore</td>
			<td>116835</td>
			<td>Used to TLC</td>
		</tr>
		<tr>
			<td>Trypticase Peptone</td>
			<td>Sigma-Aldrich</td>
			<td>Z699209</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Tryptone</td>
			<td>Sigma-Aldrich</td>
			<td>T7293</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Tween 80</td>
			<td>Solarbio</td>
			<td>T8360</td>
			<td>Salt solution of medium</td>
		</tr>
		<tr>
			<td>Valeric</td>
			<td>Sigma-Aldrich</td>
			<td>75054</td>
			<td>Standard sample for SCFA</td>
		</tr>
		<tr>
			<td>Vitamin K1</td>
			<td>Sigma-Aldrich</td>
			<td>V3501</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>Vortex oscillator</td>
			<td>Scientific Industries</td>
			<td>Vortex.Genie2</td>
			<td>Use to vortexing</td>
		</tr>
		<tr>
			<td>Yeast Extract</td>
			<td>Sigma-Aldrich</td>
			<td>Y1625</td>
			<td>The component of medium</td>
		</tr>
		<tr>
			<td>ZnSO4.7H2O</td>
			<td>Sigma-Aldrich</td>
			<td>Z0251</td>
			<td>The component of medium</td>
		</tr>
	</tbody>
</table>

analysis of interactions between endobiotics and human gut microbiota using in vitro bath fermentation systems

Human intestinal microorganisms have recently become an important target of research in promoting human health and preventing diseases. Consequently, investigations of interactions between endobiotics (e.g., drugs and prebiotics) and gut microbiota have become an important research topic. However, in vivo experiments with human volunteers are not ideal for such studies due to bioethics and economic constraints. As a result, animal models have been used to evaluate these interactions in vivo. Nevertheless, animal model studies are still limited by bioethics considerations, in addition to differing compositions and diversities of microbiota in animals vs. humans. An alternative research strategy is the use of batch fermentation experiments that allow evaluation of the interactions between endobiotics and gut microbiota in vitro. To evaluate this strategy, bifidobacterial (Bif) exopolysaccharides (EPS) were used as a representative xenobiotic. Then, the interactions between Bif EPS and human gut microbiota were investigated using several methods such as thin-layer chromatography (TLC), bacterial community compositional analysis with 16S rRNA gene high-throughput sequencing, and gas chromatography of short-chain fatty acids (SCFAs). Presented here is a protocol to investigate the interactions between endobiotics and human gut microbiota using in vitro batch fermentation systems. Importantly, this protocol can also be modified to investigate general interactions between other endobiotics and gut microbiota.

The production of mucoid EPS could be observed in B. longum cultures on PYG plates after anaerobic incubation for 72 h (Figure 1A). Centrifugation of culture scrapes, followed by ethanol precipitation and drying, resulted in the collection of cellulose-like EPS (Figure 1B). Dried EPS and soluble starch were then used as carbon sources for fermentation cultures. TLC was used for oligosaccharide separation and purity analysis due to its low cost and rapid...

Watch this Scientific Journal Video about Analysis of Interactions between Endobiotics and Human Gut Microbiota Using In Vitro Bath Fermentation Systems at JoVE.com

Analysis of Interactions between Endobiotics and Human Gut Microbiota Using In Vitro Bath Fermentation Systems

Described here is a protocol to investigate the interactions between endobiotics and human gut microbiota using in vitro batch fermentation systems.

Human intestinal microorganisms have recently become an important target of research in promoting human health and preventing diseases. Consequently, ...

Our protocol can be widely used for high-throughput and rapid screening of the interactions between endobiotics and human gut microbiota. Low cost and avoidance of interference effects from the host's metabolism. This procedure has the potential to be used in diagnosis.First, dissolve BIF EPS and starch individually in hot water on a magnetic agitator to make both the concentration of eight grams per liter. In the prepared basic culture medium, VI, add 100 milliliters of the BIF EPS solution to make culture VI BIF solution. Add 100 milliliters of the starch solution to make culture VI starch solution.Autoclave the two media with carbon source, and the medium without carbon source as a control, at 121 degrees Celsius for 15 minutes. Allow them to cool to room temperature and add haymen and cysteine. Transfer a sub-sample of five milliliters of each medium to culture tubes.And store in an anaerobic incubator. Store the remaining media at four degrees Celsius. To prepare human fecal sample, transfer one gram of fresh fecal sample into 10 milliliters of 0.1 molar anaerobic PBS at pH seven in a glass beaker.Then use a glass rod to stir it to achieve a slurry. In an anaerobic chamber, add 500 microliters of the filtered fecal slurry into the three prepared fermentation media, individually. Then, incubate at 37 degrees Celsius.After 24 hours and 48 hours, collect two milliliters of fermented samples in the anaerobic chamber. And then centrifuge outside of the chamber at 6000 times G, for three minutes. Carefully transfer the supernatants to new centrifuge tubes that will be used for polysaccharide degradation analysis and short-chain fatty acid measurements.Store the centrifugation pellets at 80 degrees Celsius. Load 0.2 microliters of the fermented supernatants onto each pre-coated silica gel 60 TLC aluminum plate and swirl to spread. Then use a hair dryer with hot air to dry.Immerse one end of the sampled plates in 20 milliliters of formic acid:n-butanol:water solution for several minutes, until the electrophoresis extends almost to the other end. Then take out the plates with forceps, and dry with a hair dryer. Then soak the plates in the orcinol reagent for two minutes to dye.And dry again. Transfer the plates to a baking oven at 120 degrees Celsius to heat for three minutes. Then take pictures of the plate to evaluate degradation of EPS by measuring TLC bands.To study the effects of EPS on SCFA production, add one milliliter of the fermented supernatants to two-milliliter centrifuge tubes and add 0.2 milliliters of 25 weight/volume percent of metaphosphoric acid to each sample. Vortex to thoroughly mix the solutions. Centrifuge the mixtures at 13, 000 times G for 20 minutes.In the meantime, prepare solutions of 120 millimolar acetic, propionic, butyric, isobutyric, valeric, and isovaleric acids in tubes. Then add one milliliter of each prepared acid to a tube containing 1.2 milliliters of 25 weight/volume percent metaphosphoric acid. And load them into the sample bottle of the gas-chromatography instrument as the standard cocktails.Take the tubes out of the centrifuge, and transfer the supernatants to fresh tubes. Use a syringe equipped with 0.22 micron filter to filter the supernatants into new tubes for gas-chromatography analysis. In this study, the production of mucoid EPS was observed in bifidobacterium longum cultures on PYG plates, after anaerobic incubation for 72 hours.Centrifugation of culture scrapes, followed by ethanol precipitation and drying, resulted in collection of cellulose-like EPS. TLC analysis revealed that the degradation rate of starch by human fecal microbiota was faster than that of BIF EPS. Principal Coordinate Analysis shows culture VI BIF, and culture VI starch groups, clustered separately from each other, indicating that EPS and starch availability differentially shape human fecal bacterial communities.Linear Discriminant Analysis on effect size shows the genera collinsella, coprococcus, parabacteroides, and rhodopseudomonas were significantly more abundant in the culture VI BIF samples than in the culture VI starch samples. Furthermore, GC measurements show SCFAs that were measured from fermentation cultures included acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids. Following fermentation for 24 hours and 48 hours, five of the six SCFA concentrations were similar and not statistically different between the culture VI BIF, culture VI starch, and culture VI groups.However, proprionic acid concentrations were significantly higher in the culture VI BIF group than in the culture VI starch group, after 48 hours of fermentation. Do this experiment under anaerobic conditions, and then transfer the fixed samples into an anaerobic incubator as soon as possible. Some of the TLC reagents are hazardous.You should be careful to use them.

analysis-interactions-between-endobiotics-human-gut-microbiota-using

Research

JoVE Journal

Immunology and Infection

6.7K 조회수.  Hunan University of Science and Engineering. 우리의 프로토콜은 인체 생물학과 인간 창자 microbiota 사이 상호 작용의 높은 처리량 그리고 급속한 검열을 위해 넓게 이용될 수 있습니다. 낮은 비용과 호스트의 신진 대사에서 간섭 효과의 회피. 이 절차는 진단에 사용될 가능성이 있습니다.첫째, BIF EPS를 용해하고 자기 교반기의 뜨거운 물에 개별적으로 전분을 녹여 리터 당 8 그램의 농도를 모두 만듭니다. 준비된 기?...