scholarly journals Geographical Relationships between Long-Tailed Goral (Naemorhedus caudatus) Populations Based on Gut Microbiome Analysis

2021 ◽  
Vol 9 (9) ◽  
pp. 2002
Author(s):  
Chang Eon Park ◽  
Bum-Joon Cho ◽  
Min-Ji Kim ◽  
Hee Cheon Park ◽  
Jae-Ho Shin
Keyword(s):  
Gut Microbiome ◽  
Alpha Diversity ◽  
Migration Route ◽  
Ecological Studies ◽  
Northern Asia ◽  
Microbiome Composition ◽  
Microbiome Analysis ◽  
Northern Regions ◽  
Regional Population ◽  
Relational Network

The long-tailed goral (Naemorhedus caudatus) is an endangered species found in the mountains of eastern and northern Asia. Its populations have declined for various reasons, and this species has been designated as legally protected in South Korea. Although various ecological studies have been conducted on long-tailed gorals, none have investigated the gut microbiome until now. In the present study, we compared the diversity and composition of the gut microbiome of seven populations of Korean long-tailed gorals. By analyzing the gut microbiome composition for each regional population, it was found that four phyla—Firmicutes, Actinobacteriota, Bacteroidota, and Proteobacteria—were the most dominant in all regions on average. The alpha diversity of the gut microbiome of the goral population in the northern regions was high, while that in the southern regions was low. Through the analysis of beta diversity, the seven long-tailed goral populations have been divided into three groups: the Seoraksan population, the Samcheock population, and the Wangpicheon population. It was possible to confirm the regional migration of the animals using the gut microbiome based on the site-relational network analysis. It was found that the most stable population of long-tailed gorals in Korea was the Seoraksan population, and the closely related groups were the Samcheok and Wangpicheon populations, respectively. Wangpicheon appeared to be a major point of dispersal in the migration route of Korean long-tailed gorals.

scholarly journals Immune Gene Expression Covaries with Gut Microbiome Composition in Stickleback

mBio ◽  
2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Lauren E. Fuess ◽  
Stijn den Haan ◽  
Fei Ling ◽  
Jesse N. Weber ◽  
Natalie C. Steinel ◽  
...  
Keyword(s):  
Gene Expression ◽  
Microbial Communities ◽  
Gut Microbiome ◽  
Alpha Diversity ◽  
Host Immunity ◽  
Host Gene ◽  
Microbiota Composition ◽  
Host Gene Expression ◽  
Microbiome Composition ◽  
Immune Genes

ABSTRACT Commensal microbial communities have immense effects on their vertebrate hosts, contributing to a number of physiological functions, as well as host fitness. In particular, host immunity is strongly linked to microbiota composition through poorly understood bi-directional links. Gene expression may be a potential mediator of these links between microbial communities and host function. However, few studies have investigated connections between microbiota composition and expression of host immune genes in complex systems. Here, we leverage a large study of laboratory-raised fish from the species Gasterosteus aculeatus (three-spined stickleback) to document correlations between gene expression and microbiome composition. First, we examined correlations between microbiome alpha diversity and gene expression. Our results demonstrate robust positive associations between microbial alpha diversity and expression of host immune genes. Next, we examined correlations between host gene expression and abundance of microbial taxa. We identified 15 microbial families that were highly correlated with host gene expression. These families were all tightly correlated with host expression of immune genes and processes, falling into one of three categories—those positively correlated, negatively correlated, and neutrally related to immune processes. Furthermore, we highlight several important immune processes that are commonly associated with the abundance of these taxa, including both macrophage and B cell functions. Further functional characterization of microbial taxa will help disentangle the mechanisms of the correlations described here. In sum, our study supports prevailing hypotheses of intimate links between host immunity and gut microbiome composition. IMPORTANCE Here, we document associations between host gene expression and gut microbiome composition in a nonmammalian vertebrate species. We highlight associations between expression of immune genes and both microbiome diversity and abundance of specific microbial taxa. These findings support other findings from model systems which have suggested that gut microbiome composition and host immunity are intimately linked. Furthermore, we demonstrate that these correlations are truly systemic; the gene expression detailed here was collected from an important fish immune organ (the head kidney) that is anatomically distant from the gut. This emphasizes the systemic impact of connections between gut microbiota and host immune function. Our work is a significant advancement in the understanding of immune-microbiome links in nonmodel, natural systems.

scholarly journals Cruciferous Vegetable Intake Results in Differentially Modified Gut Microbiome Composition of Mice Fed a High Fat Diet or a Western Diet

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1595-1595
Author(s):  
Sabrina Trudo ◽  
Rosa Moreno ◽  
Jeong Hoon Pan ◽  
Daniel Gallaher ◽  
Jae Kyeom Kim ◽  
...  
Keyword(s):  
Gut Microbiome ◽  
Vegetable Intake ◽  
Body Weight Gain ◽  
Alpha Diversity ◽  
Western Diet ◽  
Index Number ◽  
Standard Diet ◽  
Jaccard Distance ◽  
Microbiome Composition ◽  
Distinct Cluster

Abstract Objectives Cruciferous (CRU; rich in glucosinolates) and apiaceous (API; rich in furanocoumarins) vegetable intake decrease colon cancer risk markers, likely through different mechanisms. Previous reports suggest background diets influence efficacy of bioactives. Here, we determined the effects on the composition of the gut microbiome of CRU and API supplementation to different background diets, diet-induced obesity (DIO) and the total western diet (TWD). Methods C57BL/6J male mice were fed standard diet (AIN93G), DIO, DIO with 21% (w/w) CRU (DIO + CRU), DIO with 21% (w/w) API (DIO + API), TWD, TWD with CRU (TWD + CRU), or TWD with API (TWD + API). After 12 weeks, cecal contents were collected for 16S rRNA sequencing and data analyzed by mothur. Results There were no differences in body weight gain except mice fed DIO + CRU gained more than mice fed AIN-93G or TWD. Lachnospiraceae was increased by CRU supplementation to both DIO and TWD and by API supplementation to TWD. CRU increased alpha diversity [Shannon Index, number of observed Operational Taxonomic Unit (OTUs)] compared to DIO and TWD. Regarding beta diversity, DIO + CRU showed distinct cluster compared to DIO (Bray-Curtis, ANOSIM, R = 0.35, P < 0.001; Jaccard distance, R = 0.47, P < 0.001). TWD + CRU showed distinct cluster compared to TWD (Bray-Curtis, R = 0.59, P < 0.001; Jaccard distance, R = 0.62, P < 0.001). API did not change alpha diversity, but did affect beta diversities with distinct clusters between API groups and their basal diet groups (Jaccard distance, R = 0.36 and 0.31 for DIO and TWD, respectively, P < 0.05). Among top 25 discriminating features between DIO and TWD and their supplementation of API and CRU, there were 9 shared OTUs including Lachnospiraceae, Clostridium XlVa, Clostridiales, Eisenbergiella, and Clostridium IV. Akkermansia were decreased in DIO + CRU compared with DIO. In TWD panel, Bifidobacterium and Erysipelotrichaceae decreased in TWD + CRU, while Turicibacter were identified as TWD + CRU signature. Erysipelotrichaceae and Bifidobacterium differentiated AIN-93G, DIO, and TWD. Conclusions CRU supplementation of DIO and TWD altered gut microbiome composition with some differences based on background diet. API also altered composition, albeit to a lesser extent. Funding Sources University of Arkansas, Fulbright Nicaragua Fellow.

scholarly journals Safety and Modulatory Effects of Humanized Galacto-Oligosaccharides on the Gut Microbiome

2021 ◽  
Vol 8 ◽  
Author(s):  
Jason W. Arnold ◽  
Hunter D. Whittington ◽  
Suzanne F. Dagher ◽  
Jeffery Roach ◽  
M. Andrea Azcarate-Peril ◽  
...  
Keyword(s):  
Gut Microbiome ◽  
Alpha Diversity ◽  
Biological Synthesis ◽  
Glycosyl Hydrolases ◽  
Microbiome Composition ◽  
Metabolic Substrates ◽  
Beneficial Impact ◽  
Infant Gut Microbiome ◽  
Membrane Bound

Complex dietary carbohydrate structures including β(1–4) galacto-oligosaccharides (GOS) are resistant to digestion in the upper gastrointestinal (GI) tract and arrive intact to the colon where they benefit the host by selectively stimulating microbial growth. Studies have reported the beneficial impact of GOS (alone or in combination with other prebiotics) by serving as metabolic substrates for modulating the assembly of the infant gut microbiome while reducing GI infections. N-Acetyl-D-lactosamine (LacNAc, Galβ1,4GlcNAc) is found in breast milk as a free disaccharide. This compound is also found as a component of human milk oligosaccharides (HMOs), which have repeating and variably branched lactose and/or LacNAc units, often attached to sialic acid and fucose monosaccharides. Human glycosyl-hydrolases do not degrade most HMOs, indicating that these structures have evolved as natural prebiotics to drive the proper assembly of the infant healthy gut microbiota. Here, we sought to develop a novel enzymatic method for generating LacNAc-enriched GOS, which we refer to as humanized GOS (hGOS). We showed that the membrane-bound β-hexosyl transferase (rBHT) from Hamamotoa (Sporobolomyces) singularis was able to generate GOS and hGOS from lactose and N-Acetyl-glucosamine (GlcNAc). The enzyme catalyzed the regio-selective, repeated addition of galactose from lactose to GlcNAc forming the β-galactosyl linkage at the 4-position of the GlcNAc and at the 1-position of D-galactose generating, in addition to GOS, LacNAc, and Galactosyl-LacNAc trisaccharides which were produced by two sequential transgalactosylations. Humanized GOS is chemically distinct from HMOs, and its effects in vivo have yet to be determined. Thus, we evaluated its safety and demonstrated the prebiotic's ability to modulate the gut microbiome in 6-week-old C57BL/6J mice. Longitudinal analysis of gut microbiome composition of stool samples collected from mice fed a diet containing hGOS for 5 weeks showed a transient reduction in alpha diversity. Differences in microbiome community composition mostly within the Firmicutes phylum were observed between hGOS and GOS, compared to control-fed animals. In sum, our study demonstrated the biological synthesis of hGOS, and signaled its safety and ability to modulate the gut microbiome in vivo, promoting the growth of beneficial microorganisms, including Bifidobacterium and Akkermansia.

scholarly journals An online atlas of human plasma metabolite signatures of gut microbiome composition

2021 ◽  
Author(s):  
Koen F. Dekkers ◽  
Sergi Sayols-Baixeras ◽  
Gabriel Baldanzi ◽  
Christoph Nowak ◽  
Ulf Hammar ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Gut Microbiome ◽  
High Performance ◽  
Alpha Diversity ◽  
Plasma Metabolites ◽  
Uremic Toxin ◽  
Metagenomic Sequencing ◽  
Microbiome Composition ◽  
Plasma Metabolite

The human gut microbiota produces a variety of small compounds, some of which enter the bloodstream and impact host health. Conversely, various exogenous nutritional and pharmaceutical compounds affect the gut microbiome composition before entering circulation. Characterization of the gut microbiota—host plasma metabolite interactions is an important step towards understanding the effects of the gut microbiota on human health. However, studies involving large and deeply phenotyped cohorts that would reveal such meaningful interactions are scarce. Here, we used deep metagenomic sequencing and ultra-high-performance liquid chromatography linked to mass spectrometry for detailed characterization of the fecal microbiota and plasma metabolome, respectively, of 8,584 participants invited at age 50 to 64 of the Swedish CArdioPulmonary bioImage Study (SCAPIS). After adjusting for multiple comparisons, we identified 1,008 associations between species alpha diversity and plasma metabolites, and 318,944 associations between specific gut metagenomic species and plasma metabolites. The gut microbiota explained up to 50% of the variance of individual plasma metabolites (mean of 4.7%). We present all results as the searchable association atlas "GUTSY" as a rich resource for mining associations, and exemplify the potential of the atlas by presenting novel associations between oral medication and the gut microbiome, and microbiota species strongly associated with levels of the uremic toxin p-cresol sulfate. The association atlas can be used as the basis for targeted studies of perturbation of specific bacteria and for identification of candidate plasma biomarkers of gut flora composition.

Dysbiosis in early sepsis can be modulated by a multispecies probiotic: a randomised controlled pilot trial

2019 ◽  
Vol 10 (3) ◽  
pp. 265-278 ◽  
Author(s):  
V. Stadlbauer ◽  
A. Horvath ◽  
I. Komarova ◽  
B. Schmerboeck ◽  
N. Feldbacher ◽  
...  
Keyword(s):  
Gut Microbiome ◽  
Early Stage ◽  
Pilot Trial ◽  
Alpha Diversity ◽  
Gut Barrier ◽  
Double Blind ◽  
Microbiome Composition ◽  
Gut Barrier Function ◽  
Probiotic Intervention ◽  
Early Sepsis

The gut is hypothesised to play an important role in the development and progression of sepsis. It is however unknown whether the gut microbiome and the gut barrier function is already altered early in sepsis development and whether it is possible to modulate the microbiome in early sepsis. Therefore, a randomised, double blind, placebo-controlled pilot study to examine the alterations of the microbiome and the gut barrier in early sepsis and the influence of a concomitant probiotic intervention on dysbiosis at this early stage of the disease was conducted. Patients with early sepsis, defined as fulfilling the sepsis definition from the 2012 Surviving Sepsis Campaign guidelines but without signs of organ failure, received multispecies probiotic (Winclove 607 based on Omnibiotic® 10 AAD) for 28 days. Gut microbiome composition, function, gut barrier and bacterial translocation were studied. Patients with early sepsis had a significantly lower structural and functional alpha diversity, clustered differently and showed structural alterations on all taxonomic levels. Gut permeability was unaltered but endotoxin, endotoxin binding proteins and peptidoglycans were elevated in early sepsis patients compared to controls. Probiotic intervention successfully increased probiotic strains in stool and led to an improvement of functional diversity. Microbiome composition and function are altered in early sepsis. Probiotic intervention successfully modulates the microbiome and is therefore a promising tool for early intervention in sepsis.

scholarly journals Supplementation of Geranylgeraniol and Tocotrienols to High-Fat Diet Shifts the Gut Microbiome Composition and Function in Type 2 Diabetic Mice

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 393-393
Author(s):  
Moamen Elmassry ◽  
Eunhee Chung ◽  
Abdul Hamood ◽  
Chwan-Li Shen
Keyword(s):  
Relative Abundance ◽  
Gut Microbiome ◽  
High Fat Diet ◽  
Alpha Diversity ◽  
Control Group ◽  
Rrna Gene ◽  
High Fat ◽  
Microbiome Composition ◽  
And Function

Abstract Objectives In recent years, characterization of gut microbiota composition and function were linked to the progression of type 2 diabetes mellitus. Recent evidence showed that Geranylgeraniol, an isoprenoid found in fruits, vegetables, and grains, improves glucose homeostasis. Similarly, Tocotrienols, a subfamily of vitamin E, also contains anti-diabetic properties. In this study, we examined the combined effect of geranylgeraniol and tocotrienols on the composition and function of gut microbiome in obese male mice. Methods Forty male C57BL/6J mice were assigned to 4 groups in a factorial design as follows: high-fat diet (HFD) (control group), HFD + geranylgeraniol [400 mg/kg diet] (GG group), HFD + tocotrienols [400 mg/kg diet] (TT group), and HFD + geranylgeraniol + tocotrienols (G + T group) for 14 weeks. 16S rRNA gene sequencing was done from cecal samples and microbiome and data analysis was performed with QIIME2 and PICRUSt2. Results Across all groups, the most abundant phyla were Verrucomicrobia, Firmicutes, Bacteroidetes, and Actinobacteria. There was no difference in alpha diversity among different groups. Different treatments influenced the relative abundance of certain bacteria. In the Bacteroidetes phylum, the relative abundance of family S24–7 increased in the TT group only. In the Firmicutes phylum, the relative abundance of family Lachnospiraceae was reduced upon the supplementation of geranylgeraniol or tocotrienols; individually or in combination. In Verrucomicrobia phylum, Akkermansia muciniphila relative abundance was reduced in the TT group but increased in the G + T group. The results of functional profiling of the gut microbiome revealed that geranylgeraniol supplementation caused an increase in the proportion of biosynthetic pathways related to purine, pyrimidine, and inosine-5’-phosphate and hexitol fermentation, and a decrease in the proportion of pathways involved in the biosynthesis of isoleucine, valine, histidine, arginine, and chorismate. The G + T group increased pathways related to thiamine diphosphate biosynthesis, and decreased others involved into sulfur oxidation and methylerythritol phosphate. Conclusions The influence of geranylgeraniol and tocotrienols supplementation on gut microbiome composition and function, suggests a prebiotic potential for the potential of geranylgeraniol and tocotrienols. Funding Sources American River Nutrition, LLC, Hadley, MA.

scholarly journals The Western Dietary Pattern Combined with Vancomycin-Mediated Changes to the Gut Microbiome Exacerbates Colitis Severity and Colon Tumorigenesis

Nutrients ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 881
Author(s):  
Niklas D. Aardema ◽  
Daphne M. Rodriguez ◽  
Arnaud J. Van Wettere ◽  
Abby D. Benninghoff ◽  
Korry J. Hintze
Keyword(s):  
Colorectal Cancer ◽  
Gut Microbiome ◽  
Tumor Development ◽  
Alpha Diversity ◽  
Basal Diet ◽  
Plain Water ◽  
Microbiome Composition ◽  
Colon Tumorigenesis ◽  
Induced Changes ◽  
The Impact

Previous work by our group using a mouse model of inflammation-associated colorectal cancer (CAC) showed that the total Western diet (TWD) promoted colon tumor development. Others have also shown that vancomycin-mediated changes to the gut microbiome increased colorectal cancer (CRC). Therefore, the objective of this study was to determine the impact of vancomycin on colon tumorigenesis in the context of a standard mouse diet or the TWD. A 2 × 2 factorial design was used, in which C57Bl/6J mice were fed either the standard AIN93G diet or TWD and with vancomycin in the drinking water or not. While both the TWD and vancomycin treatments independently increased parameters associated with gut inflammation and tumorigenesis compared to AIN93G and plain water controls, mice fed the TWD and treated with vancomycin had significantly increased tumor multiplicity and burden relative to all other treatments. Vancomycin treatment significantly decreased alpha diversity and changed the abundance of several taxa at the phylum, family, and genus levels. Conversely, basal diet had relatively minor effects on the gut microbiome composition. These results support our previous research that the TWD promotes colon tumorigenesis and suggest that vancomycin-induced changes to the gut microbiome are associated with higher tumor rates.

scholarly journals Black Raspberry Supplementation Alters the Gut Microbiome and Improves Alpha Diversity in a Mouse Model of Inflammation-Associated Colorectal Cancer

2021 ◽  
Vol 5 (Supplement_2) ◽  
pp. 1177-1177
Author(s):  
Daphne Rodriguez ◽  
Eliza Owens ◽  
Sam Vassar ◽  
Ashley Bartlett ◽  
Emily Mortensen ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Gut Microbiome ◽  
Dietary Intervention ◽  
Alpha Diversity ◽  
Basal Diet ◽  
Recovery Phase ◽  
Protective Effects ◽  
Linear Discriminant ◽  
Microbiome Composition ◽  
Freeze Dried

Abstract Objectives Anti-inflammatory bioactives in black raspberries (BRB) have been shown to have protective effects on the colon epithelium and may influence gut microbiome. The goal of this study was to determine the effects of dietary intervention with BRB on the dynamic composition of the gut microbiome composition in mice. Methods Using a 2 × 2 factorial design, C57BL/6J male mice were fed the standard AIN93G diet or the total Western diet (TWD) for 16 weeks with or without 10% (w/w) whole, freeze-dried BRB powder. The azoxymethane + dextran sodium sulfate model of inflammation-associated colorectal cancer was employed to assess the dynamic response of the gut microbiome to basal diet and BRB treatment prior to, during, and after active colitis and at the study end. Microbiome composition was determined using 16s rRNA sequencing followed by diversity analyses (alpha and beta) and identification of discriminating taxa by with linear discriminant analyses by effect size (lefse). Results Alpha diversity was markedly reduced during colitis for mice consuming either AIN93G or TWD, with some improvement noted by the recovery phase. Of note, consumption of BRB for two weeks significantly increased alpha diversity measures, and BRB improved alpha diversity in mice fed the AIN93G diet during colitis. Alternatively, BRB appeared less effective in mice fed TWD. Beta diversity was also significantly affected with notable clustering of microbiomes by BRB treatment during and after colitis. Consumption of BRB affected the relative abundance of several key taxa over the course of colitis and recovery from gut injury, including Erysipelotrichaceae, Bifidobacteriaceae, Streptococcaceae, Rikenellaceae, Ruminococcaceae and Akkermansiaceae, among others. Conclusions Dietary supplementation with BRB shifted the composition of the gut microbiome during colitis and recovery from gut injury, though the effects were inconsistent with respect to the basal diet consumed. Funding Sources USDA NIFA AFRI grant no. 2018-67017-27,516 and 2014-67017-21755.

scholarly journals Changes in Microbial Community Composition Related to Sex and Colon Cancer by Nrf2 Knockout

2021 ◽  
Vol 11 ◽  
Author(s):  
Chin-Hee Song ◽  
Nayoung Kim ◽  
Ryoung Hee Nam ◽  
Soo In Choi ◽  
Jeong Eun Yu ◽  
...  
Keyword(s):  
Gut Microbiome ◽  
Microbial Community Composition ◽  
Alpha Diversity ◽  
16S Rrna Gene Sequencing ◽  
Rrna Gene ◽  
Related Factor ◽  
Invasive Adenocarcinoma ◽  
Linear Discriminant ◽  
Microbiome Composition ◽  
Male Control

The frequency of azoxymethane/dextran sulfate sodium (AOM/DSS)-induced carcinogenesis in male mice is higher than that in female mice. Previous studies have reported that 17β-estradiol inhibits tumorigenesis in males by modulating nuclear factor-erythroid 2-related factor 2 (Nrf2). This study aimed to investigate the changes in mouse gut microbiome composition based on sex, AOM/DSS-induced colorectal cancer (CRC), and Nrf2 genotype. The gut microbiome composition was determined by 16S rRNA gene sequencing fecal samples obtained at week 16 post-AOM administration. In terms of sex differences, our results showed that the wild-type (WT) male control mice had higher alpha diversity (i.e. Chao1, Shannon, and Simpson) than the WT female control mice. The linear discriminant analysis effect size (LEfSe) results revealed that the abundances of Akkermansia muciniphila and Lactobacillus murinus were higher in WT male control mice than in WT female controls. In terms of colon tumorigenesis, the alpha diversity of the male CRC group was lower than that of the male controls in both WT and Nrf2 KO, but did not show such changes in females. Furthermore, the abundance of A. muciniphila was higher in male CRC groups than in male controls in both WT and Nrf2 KO. The abundance of Bacteroides vulgatus was higher in WT CRC groups than in WT controls in both males and females. However, the abundance of L. murinus was lower in WT female CRC and Nrf2 KO male CRC groups than in its controls. The abundance of A. muciniphila was not altered by Nrf2 KO. In contrast, the abundances of L. murinus and B. vulgatus were changed differently by Nrf2 KO depending on sex and CRC. Interestingly, L. murinus showed negative correlation with tumor numbers in the whole colon. In addition, B. vulgatus showed positive correlation with inflammatory markers (i.e. myeloperoxidase and IL-1β levels), tumor numbers, and high-grade adenoma, especially, developed mucosal and submucosal invasive adenocarcinoma at the distal part of the colon. In conclusion, Nrf2 differentially alters the gut microbiota composition depending on sex and CRC induction.

scholarly journals The Role of Gut Microbiome Perturbation in Fatigue Induced by Repeated Stress from Chemoradiotherapy: A Proof of Concept Study

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Velda J. González-Mercado ◽  
Josué Pérez-Santiago ◽  
Debra Lyon ◽  
Israel Dilán-Pantojas ◽  
Wendy Henderson ◽  
...  
Keyword(s):  
Gut Microbiome ◽  
Alpha Diversity ◽  
Total Sample ◽  
Fecal Microbiota ◽  
Proof Of Concept ◽  
Fatigue Score ◽  
Microbiome Composition ◽  
Concept Study ◽  
Symptom Ratings ◽  
Rectal Cancers

Objectives. The objectives of this proof of concept study were to (a) examine the temporal changes in fatigue and diversity of the gut microbiome over the course of chemoradiotherapy (CRT) in adults with rectal cancers; (b) investigate whether there are differences in diversity of the gut microbiome between fatigued and nonfatigued participants at the middle and at the end of CRT; and (c) investigate whether there are differences in the relative abundance of fecal microbiota at the phylum and genus levels between fatigued and nonfatigued participants at the middle and at the end of CRT. Methods. Stool samples and symptom ratings were collected prior to the inception of CRT, at the middle (after 12–16 treatments) and at the end (after 24–28 treatments) of the CRT. Descriptive statistics and Mann–Whitney U test were computed for fatigue. Gut microbiome data were analyzed using the QIIME2 software. Results. Participants (N = 29) ranged in age from 37 to 80 years. The median fatigue score significantly changed at the end of CRT (median = 23.0) compared with the median score before the initiation of CRT for the total sample (median = 17.0; p≤0.05). At the middle of CRT, the alpha diversity (abundance of Operational Taxonomic Units) was lower for fatigued participants (149.30 ± 53.1) than for nonfatigued participants (189.15 ± 44.18, t(23) = 2.08, p≤0.05). A similar trend was observed for the Shannon and Faith diversity indexes at the middle of CRT. However, at the end of CRT, there were no significant differences for any alpha diversity indexes between fatigued and nonfatigued participants. Proteobacteria, Firmicutes, and Bacteroidetes were the dominant phyla for fatigued participants, and Escherichia, Bacteroides, Faecalibacterium, and Oscillospira were the most abundant genera for fatigued participants. Conclusion. CRT-associated perturbation of the gut microbiome composition may contribute to fatigue.

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