Tag Archives: Carbohydrate

Microbiology

Do seasonal changes in food types lead to changes in the composition and structure of gut microbiota?

Leave a comment

Bhavana KunkalikarBy Bhavana KunkalikarMar 6 2023Reviewed by Danielle Ellis, B.Sc.

In a recent study published in the Frontiers in Microbiology, researchers assessed the impact of diet or macronutrient consumption on the function and structure of gut microbiota.

Study: Does diet or macronutrients intake drive the structure and function of gut microbiota? Image Credit: Alpha Tauri 3D Graphics/Shutterstock
Study: Does diet or macronutrients intake drive the structure and function of gut microbiota? Image Credit: Alpha Tauri 3D Graphics/Shutterstock

Background

Shifting ingestive behavior is crucial for animals to adjust to environmental change. Studies have recognized that changes in animal feeding habits lead to gut microbiota structure alterations. However, further research is required to understand the alterations incident in the structure as well as the function of the gut microbiota that occur in response to alterations in nutrient consumption or food types.

About the study

In the present study, researchers explored how animal feeding techniques influence nutrient consumption and further affect the content and digestive function of the gut microbiota.

The study observation site was in the Guanyin Mountain National Natural Reserve in the Qinling Mountains, northwest of Fuping County, Shaanxi Province, China. During a year, this area experiences conventional and four different seasons. According to climate, the seasons are as follows: Spring between March and May, Summer between June and August, Autumn between September and November, and Winter between December and February.

The team compiled feeding information for the four seasonal groupings. For data collection, a month with typical phenological characteristics for each season: March for Spring, June for Summer, October for Autumn, and December for Winter.

All of the 78 golden snub-nosed monkeys in the study group were accustomed to the presence of researchers. The team identified both adult and young individuals in the study cohort. Due to the necessity for quantitative observational data, the natural feeding area of the study animals was restricted. The team provided five kilograms of maize twice daily at 10 am and 3 pm as supplemental nourishment for the group. The feed grounds were evenly strewn with corn kernels.

The team randomly selected one individual per day and observed the subject animal continuously from sunrise to dusk to record data related to its feeding pattern. Furthermore, the type of food, quantity, preset units, and feeding duration were recorded. After the subject had finished eating, food samples were gathered from the leftovers.

Food samples were collected using conventional procedures, their nutritional content was assessed, and their energy content was computed. The lipid, starch, water-soluble carbohydrate (WSC), acid detergent fiber (ADF), neutral detergent fiber (NDF), acid detergent lignin (ADL), ash content of each food, and available protein (AP) were evaluated.

Results

Data related to 96 days of feeding across four months were obtained from the target population. It was discovered that the normal diet of golden snub-nosed monkeys in the wild comprised 24 plant species from 16 families. A total of six plant parts, including branches, buds, seeds, barks, leaves, and stems, were consumed by the subjects.

Throughout the year, wild snub-nosed monkeys eat 33.43% of bark, 3.09% of seed, 1.33% of bud, 3.25% of brunch, 0.17% of the stem, and 58.72% of the leaf. Nonetheless, there were significant variations in the number of plant materials consumed over the four seasons. Herbaceous stems were harvested only in tiny quantities in the Spring. Mostly, seeds were harvested in the Spring and fall. The harvesting of leaves occurred throughout the year. Throughout fall and Winter, when leaves become sparse, especially in Winter, barks, buds, and brunches were the principal sources of nutrition.

The species composition was evaluated to explore seasonal changes in gut microbiota in greater depth. Species annotation revealed that most OTUs could be assigned taxonomically at the phylum and order levels, but assignments reduced dramatically at the genus level.

The top 10 phyla out of 38 phyla recognized dominant phyla, including Bacteroidetes, Firmicutes, Spirochaetes, Proteobacteria, Tenericutes, Planctomycetes, Verrucomicrobia, Epsilonbacteriaeota, Euryarchaeota, and Fibrobacteres comprised 99% of the total abundance ratio. They comprised the majority of the golden snub-nosed monkeys’ gut microbiome.

Three hundred ninety-five metabolic pathways were found based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database’s function prediction. Gut microbes were primarily engaged in the metabolism of nucleotides, carbohydrates, glycans and their production, amino acids, terpenoids, lipids, cofactors, polyketides, and vitamins.

Moreover, some annotated functions pertaining to macronutrients exhibited relatively high abundance, including glycolysis/gluconeogenesis, pyruvate metabolism, sucrose and starch metabolism, glycerolipid metabolism, fatty acid synthesis in lipid metabolism, and pentose phosphate pathway in glycerophospholipid metabolism and carbohydrate metabolism.

Conclusion

The study findings showed a considerable seasonal change in the food consumption and nutritional intake of golden snub-nosed monkeys, with three macronutrients being higher in Autumn and Summer and lower in Winter and Spring. Seasonal dietary changes are the primary source of seasonal shifts in gut microbiota. The results indicated that bacteria in the gut compensate for inadequate macronutrient intake through microbial metabolic functions.

Journal reference:
Microbiology

Differences in gut microbiome diversity attributed to dietary patterns in children with obesity

Leave a comment

Dr. Chinta SidharthanBy Dr. Chinta SidharthanFeb 16 2023Reviewed by Benedette Cuffari, M.Sc.

In a recent study published in Microbiology Spectrum, researchers found that differences in the dietary patterns of children with normal weight and those who were overweight or obese contributed to variations in the gut microbiome diversity, virulence factors of gut bacteria, and metabolic function.

Study: Virulence factors of the gut microbiome are associated with BMI and metabolic blood parameters in children with obesity. Image Credit: Africa Studio / Shutterstock.com

Study: Virulence factors of the gut microbiome are associated with BMI and metabolic blood parameters in children with obesity. Image Credit: Africa Studio / Shutterstock.com

Background

A growing body of evidence indicates that gut microbiota has a significant role in various aspects of host metabolism, including digestion, harvesting of energy, and induction of low-grade inflammation. In addition, the genetic factors of the host, as well as other characteristics such as age, diet, immunity, and gender, influence the gut microbiome composition.

Research shows that bacterial diversity in the gut and the individual’s functional capacity vary between those with normal weight and obese individuals. Gut microbiome profile variations have also been linked to metabolic disorders, lipid accumulation, and inflammation.

Lipogenesis in the liver and the regulation of appetite through hormones are also associated with gut microbiome genes.

Aside from its role in adipogenesis, superoxide reduction, and the metabolism of vitamins, gut microbiota also regulates innate immunity and the systemic, low-grade inflammatory state that can contribute to fat deposition and obesity. Therefore, Dysbiosis, which is the imbalance of gut microbiota, combined with diet, likely has a significant role in the development of obesity.

About the study

In the present study, researchers conducted a cross-sectional analysis of data from 45 children between the ages of six and 12 to determine the association between gut microbiota and obesity.

Questionnaires were used to obtain information on dietary frequencies, gender, age, and body mass index (BMI). Based on the World Health Organization (WHO) z-scores, in which BMI is adjusted for gender and age, the children were classified into two categories of overweight and obese (OWOB) and normal weight (NW).

Data from food frequency questionnaires were used to classify the dietary habits of children into two nutritional patterns. To this end, Pattern 1 was characterized by complex carbohydrates and proteins, whereas Pattern 2 comprised simple carbohydrates and saturated fats.

Shotgun metagenomics was used to assess the taxonomic diversity of the gut microbiota and metabolic capacity from genomic deoxyribonucleic acid (DNA) extracted from fecal samples. Clade-specific markers were used for the taxonomic and functional assessment of the gut bacteria. Additionally, reverse Simpson and Shannon diversity indices were calculated.

The virulence factor database was used to screen for virulence factor genes, whereas multivariate linear modeling was used to determine the association between the taxa, virulence factors, and function of gut microbes and covariates of diet, serology, and anthropometric measurements.

Study findings

Significant differences between the alpha and beta diversity of the gut microbiota were observed between the children in the NW and OWOB groups, thus suggesting that specific phyla of bacteria contribute to higher levels of energy harvest.

Furthermore, species such as Ruminococcus species, Victivallis vadensis, Mitsuokella multacida, Alistipes species, Clostridium species, and Acinetobacter johnsonii were linked to healthier metabolic parameters.

In contrast, an increase in the abundance of bacteria such as Veillonellaceae, Lactococcus, Fusicatenibacter saccharivorans, Fusicatenibacter prausnitzii, Eubacterium, Roseburia, Dialister, Coprococcus catus, Bifidobacterium, and Bilophila was identified in children with pro-inflammatory conditions and obesity.

Bacteria such as Citrobacter europaeus, Citrobacter youngae, Klebsiella variicola, Enterococcus mundtii, Gemella morbillorum, and Citrobacter portucalensis were associated with higher lipid and sugar intake, as well as higher blood biochemistry values and anthropometric measurements.

Diets high in fats and simple carbohydrates have been associated with the abundance of Citrobacter and Klebsiella species in the gut. Moreover, previous studies have indicated that these bacterial species are potential markers of inflammation, obesity, and an increase in fasting glucose.

The metabolism of menaquinones and gamma-glutamyl was negatively associated with BMI. Furthermore, the microbiomes of children in the NW group preserved a more consistent alpha diversity of virulence factors, while OWOB microbiomes exhibited a dominance of virulence factors.

Differences in the metabolic capacities pertaining to biosynthesis pathways of vitamins, carriers, amino acids, nucleotides, nucleosides, amines, and polyamines, as well as the degradation of nucleotides, nucleosides, and carbohydrate-sugars, were also found between the NW and OWOB groups.

Conclusions

Dietary profiles and the diversity of gut microbiota were found to be interconnected and associated with changes in metabolic parameters, the dominance of virulence factors, and obesity. Changes in gut microbiome diversity and relative abundance have been linked to obesity, inflammatory responses, and metabolic disorders.

Taken together, the study findings suggested that the prevalence of virulence factors, as well as the metabolic and genetic roles of gut microbiota in increasing inflammation, can help identify individuals at an increased risk of childhood obesity.

Journal reference:
  • Murga-Garrido, S. M., Ulloa-Pérez, E. J., Díaz-Benítez, C. E., et al. (2023). Virulence factors of the gut microbiome are associated with BMI and metabolic blood parameters in children with obesity. Microbiology Spectrum. doi:10.1128/spectrum.03382-22
Microbiology

Study illuminates how a typical gut bacterium spreads through the body

Leave a comment

Reviewed by Emily Henderson, B.Sc.Nov 10 2022

A typical gut bacterium that can spread through the body and cause a serious infection resists natural immune defenses and antibiotics by enhancing its protective outer layer, known as the cell envelope, according to a new study by Weill Cornell Medicine investigators. The finding suggests possible new ways to target these bacterial infections.

The research, published Nov. 10 in mBio, illuminates some of the underlying changes that may occur when Enterococcus faecalis (E. faecalis) populations move through the epithelial cells lining of the intestine and escape to reach other body sites.

Systemic infections with E. faecalis can be lethal because this microbe has a remarkable ability to adapt to various environments and resist treatments.”

Dr. Diana K. Morales, principal investigator, assistant professor of microbiology and immunology in obstetrics and gynecology at Weill Cornell Medicine

People at risk of developing these infections include those who are taking antibiotics or who have compromised immune systems, which facilitate E. faecalis overgrowth in the intestine. Understanding how E. faecalis moves out of the gut and spreads may one day help scientists find small molecules to stop the bacterium’s extra-intestinal dissemination, preventing dangerous infections.

How the bacterium can move out of the intestine and to other organs has remained largely unexplored. However, researchers have observed that two different populations of the same species of bacterium exist, Dr. Morales said. One population develops traits that allow it to pass through the intestinal barrier acquiring an advantageous resistance to antimicrobials, while the other stays put.

In a series of previous laboratory studies of the bacterium, the researchers found that motile E. faecalis produces molecules formed by sugar chains called polysaccharides that allow the bacterium to aggregate or clump together. “When these bacteria aggregate, they seem to develop an ability to move,” Dr. Morales said.

In the current study, the investigators, including lead author Dr. Yusibeska Ramos, a research associate in obstetrics and gynecology, found that the motile form of E. faecalis has a cell envelope containing increased amounts of glycolipids, which are fat molecules linked with a carbohydrate. Enhanced production of cell envelope glycolipids appears to help the bacterium to resist extracellular stressors. These stressors include the antimicrobial agent daptomycin, a common treatment for E. faecalis infection, and β-defensins, small molecules intestinal epithelial cells produce to deter infection.

The researchers also found that genetic mutations that inhibit glycolipid production made E. faecalis more sensitive to these stressors and reduced the ability of the bacterium to penetrate cell surfaces and move through intestinal epithelial cells.

The next step for the researchers is to evaluate additional in vivo models to confirm whether the molecular pathways uncovered in the current study are needed for the bacterium to exit the intestine. “We are also interested in identifying pharmacological approaches that can target these specific pathways with the goal of one day helping patients better fight infections by this gut microbe,” Dr. Morales said.

Source:

Weill Cornell Medicine

Journal reference:

Ramos, Y., et al. (2022) Remodeling of the Enterococcal Cell Envelope during Surface Penetration Promotes Intrinsic Resistance to Stress. mBio. doi.org/10.1128/mbio.02294-22.