Human Colonic Microbiota: Ecology, Physiology and Metabolic Potential of Intestinal Bacteria

Abstract Background: The small intestine, while serving as the main absorption organ, also possesses a unique bacterial environment and holds the critical function of conversion of primary bile acids. Bile acids are, in turn, able to regulate bacterial composition and promote the growth of bacteria that convert primary bile acids to secondary bile acids. However, in beef cattle, few studies have explored the influence of diets on jejunal bacterial communities and examined its relationships with bile acids. Here, we examined the impact of grain- and grass-based diets on jejunal and fecal bacterial communities’ composition and investigated possible association of bacterial features with bile acids.Results: We demonstrated that the influences of diets on intestinal bacteria can be observed in young beef cattle after weaning. A significantly higher level of microbial diversity was documented in feces of grass-fed cattle comparing to grain-fed cattle. Top 20 important genera identified with random forest analysis on fecal bacterial community can be good candidates for microbial biomarkers. Moreover, the jejunal bacteria of adult Angus beef cattle exhibited significant differences in microbial composition and metabolic potential under different diets. Global balances and bacteria signatures predictive of bile acids were identified, indicative of the potential association of bacterial features with bile acids.Conclusions: The findings from this study provided novel insights into the relationships between jejunal bacteria and bile acids under different diets in Angus beef cattle. Our results should help us gain a better understanding of potential health benefits of grass-fed beef.

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Diet-induced Changes in Bacterial Communities in the Jejunum and Their Associations with Bile Acids in Angus Beef Cattle

10.21203/rs.3.rs-19919/v2 ◽

2020 ◽

Author(s):

Jianan Liu ◽

Fang Liu ◽

Wentao Cai ◽

Cunling Jia ◽

Ying Bai ◽

...

Keyword(s):

Beef Cattle ◽

Bile Acids ◽

Bacterial Communities ◽

Intestinal Bacteria ◽

Microbial Composition ◽

Metabolic Potential ◽

Critical Function ◽

Potential Health ◽

Microbial Biomarkers ◽

The Impact

Abstract Background: The small intestine, while serving as the main absorption organ, also possesses a unique bacterial environment and holds the critical function of conversion of primary bile acids. Bile acids are, in turn, able to regulate bacterial composition and promote the growth of bacteria that convert primary bile acids to secondary bile acids. However, in beef cattle, few studies have explored the influence of diets on jejunal bacterial communities and examined its relationships with bile acids. Here, we examined the impact of grain- and grass-based diets on jejunal and fecal bacterial communities’ composition and investigated possible association of bacterial features with bile acids.Results: We demonstrated that the influences of diets on intestinal bacteria can be observed in young beef cattle after weaning. A significantly higher level of microbial diversity was documented in feces of grass-fed cattle comparing to grain-fed cattle. Top 20 important genera identified with random forest analysis on fecal bacterial community can be good candidates for microbial biomarkers. Moreover, the jejunal bacteria of adult Angus beef cattle exhibited significant differences in microbial composition and metabolic potential under different diets. Global balances and bacteria signatures predictive of bile acids were identified, indicative of the potential association of bacterial features with bile acids. Conclusions: The findings from this study provided novel insights into the relationships between jejunal bacteria and bile acids under different diets in Angus beef cattle. Our results should help us gain a better understanding of potential health benefits of grass-fed beef.

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Utilization efficiency of human milk oligosaccharides by human-associated Akkermansia is strain-dependent

10.1101/2021.07.26.453919 ◽

2021 ◽

Author(s):

Estefani Luna ◽

Shanthi G Parkar ◽

Nina Kirmiz ◽

Stephanie Hartel ◽

Erik Hearn ◽

...

Keyword(s):

Human Milk ◽

Growth Yield ◽

Intestinal Bacteria ◽

Glycoside Hydrolases ◽

Utilization Efficiency ◽

Human Milk Oligosaccharides ◽

Yield Strain ◽

Metabolic Potential ◽

Milk Oligosaccharides ◽

Degrading Bacteria

Akkermansia muciniphila are mucin degrading bacteria found in the human gut and are often associated with positive human health. However, despite being detected as early as one month of age, little is known about the role of Akkermansia in the infant gut. Human milk oligosaccharides (HMOs) are abundant components of human milk and are structurally similar to the oligosaccharides that comprise mucin, the preferred growth substrate of human-associated Akkermansia. A limited subset of intestinal bacteria has been shown to grow well on HMOs and mucin. We therefore examined the ability of genomically diverse strains of Akkermansia to grow on HMOs. First, we screened 85 genomes representing the four known Akkermansia phylogroups to examine their metabolic potential to degrade HMOs. Furthermore, we examined the ability of representative isolates to grow on individual HMOs in a mucin background and analyzed the resulting metabolites. All Akkermansia genomes were equipped with an array of glycoside hydrolases associated with HMO-deconstruction. Representative strains were all able to grow on HMOs with varying efficiency and growth yield. Strain CSUN-19 belonging to the AmIV phylogroup, grew to the highest level in the presence of fucosylated and sialylated HMOs. This activity may be partially related to the increased copy numbers and/or the enzyme activities of the α-fucosidases, β-sialidases, and β-galactosidases. Utilization of HMOs by strains of Akkermansia suggests that ingestion of HMOs by an infant may enrich for these potentially beneficial bacteria. Further studies are required to realize this opportunity and deliver long-lasting metabolic benefits to the human host.

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Diet-induced changes in bacterial communities in the jejunum and their associations with bile acids in Angus beef cattle

Animal Microbiome ◽

10.1186/s42523-020-00051-7 ◽

2020 ◽

Vol 2 (1) ◽

Author(s):

Jianan Liu ◽

Fang Liu ◽

Wentao Cai ◽

Cunling Jia ◽

Ying Bai ◽

...

Keyword(s):

Beef Cattle ◽

Bile Acids ◽

Bacterial Communities ◽

Intestinal Bacteria ◽

Microbial Composition ◽

Metabolic Potential ◽

Critical Function ◽

Potential Health ◽

Microbial Biomarkers ◽

The Impact

Abstract Background The small intestine, while serving as the main absorption organ, also possesses a unique bacterial environment and holds the critical function of conversion of primary bile acids. Bile acids are, in turn, able to regulate bacterial composition and promote the growth of bacteria that convert primary bile acids to secondary bile acids. However, in beef cattle, few studies have explored the influence of diets on jejunal bacterial communities and examined its relationships with bile acids. Here, we examined the impact of grain- and grass-based diets on jejunal and fecal bacterial communities’ composition and investigated possible association of bacterial features with bile acids. Results We demonstrated that the influences of diets on intestinal bacteria can be observed in young beef cattle after weaning. A significantly higher level of microbial diversity was documented in feces of grass-fed cattle comparing to grain-fed cattle. Top 20 important genera identified with random forest analysis on fecal bacterial community can be good candidates for microbial biomarkers. Moreover, the jejunal bacteria of adult Angus beef cattle exhibited significant differences in microbial composition and metabolic potential under different diets. Global balances and bacteria signatures predictive of bile acids were identified, indicative of the potential association of bacterial features with bile acids. Conclusions The findings from this study provided novel insights into the relationships between jejunal bacteria and bile acids under different diets in Angus beef cattle. Our results should help us gain a better understanding of potential health benefits of grass-fed beef.

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Intestinal microbiota balance modulates host susceptibility to infection with enteric pathogenss

Clinical & Investigative Medicine ◽

10.25011/cim.v30i4.2872 ◽

2007 ◽

Vol 30 (4) ◽

pp. 93

Author(s):

I Sekirov ◽

N Tam ◽

M Robertson ◽

C Lupp ◽

B Finlay

Keyword(s):

Intestinal Microbiota ◽

Small Animal ◽

Host Susceptibility ◽

Morphological Development ◽

Future Design ◽

Susceptibility To Infection ◽

Colonic Microbiota ◽

Food Borne ◽

Serovar Typhimurium ◽

Intestinal Pathogens

Background: During our lifetimes we develop a very complex set of interactions with the multitude of microorganisms colonizing our bodies. In the gastrointestinal system, the microbiota is highly important for morphological development, nutrition, and protection against infectious diseases. The gastrointestinal pathogens, enterohemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC) and Salmonella enterica serovar Typhimurium (ST) are food-borne pathogens that cause much morbidity and mortality worldwide. Citrobacter rodentium (Cr) is a mouse pathogen that is used in small animal models to mimic EHEC and EPEC infections. Methods: We began to characterize the contribution of intestinal microbiota to the progression of these infections. Two main phyla comprise the majority of mouse intestinal microbiota: Bacteroidetes and Firmicutes. Bacteria from a number of additional phyla are also present in smaller numbers; among them γ-Proteobacteria class, belonging to Proteobacteria phylum, is note-worthy as this class harbours many intestinal pathogens, such as ST and Cr. The mouse intestinal microbiota was perturbed using tetracycline (Tet) and streptomycin (Sm) to increase the proportion of Bacteroidetes in the colonic microbiota, and using vancomycin (Vanc) to create a predominance of Firmicutes. The mice with this perturbed microbiota were infected with ST to investigate the resultant pathology and virulence characteristics, and any additional shifts in microbiota as a result of infection. Results: Treatment of mice with Sm and Vanc was found to decrease the resistance of mice to colonization with ST, while Tet-treated mice exhibited unchanged colonization resistance. Treatment of mice with gradually increasing doses of Sm, which gradually augmented the proportion of CFB bacteria in the microbiota, resulted in progressively increasing colonization of mice by ST, as well as a step-wise increase in the ST-induced typhlitis, associated with higher levels of inflammatory markers IL-6 and KC. The increasing levels of ST colonization following both Sm and Vanc treatment were associated with an increase in the proportion of γ-Proteobacteria in the cecal and colonic microbiota, as well as a decrease in the total bacterial numbers in both organs. Conclusions: It is evident that the intestinal microbiota plays a significant role in the host’s response to infection with enteric pathogens, and its composition and numbers are also affected by the offending bacteria. Elucidation of the details regarding the contribution of the microbiota to infectious disease progression will offer novel targets for the future design of superior prevention and treatment methods.

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