Bacteroides barnesiae

Bacteroides barnesiae, a novel species within the Bacteroidetes phylum, was initially isolated from the caecum of chickens. 

As members of the human gut microbiota, Bacteroides spp. are crucial for maintaining gut homeostasis, representing about 30% of the gut microbial population. 

‍Bacteroides barnesiae strains are strictly anaerobic, non-spore-forming, non-motile, Gram-negative pleomorphic rods, forming white-greyish colonies on EG agar. They thrive optimally at 37°C in the presence of bile and produce succinic and acetic acids as major fermentation end products. 

This species does not produce indole, catalase, or urease, nor does it reduce nitrate to nitrite or liquefy gelatin. 

The metabolic activity of Bacteroides barnesiae, like other Bacteroides, significantly contributes to nutrient metabolism and gut health by breaking down complex polysaccharides. 

Being relatively newly discovered in 2006, the role of Bacteroides barnesiae in human health is still being researched.   

Overview of Bacteroides spp. [1., 7., 8., 13., 18., 21., 23., 24.] 

Bacteroides spp., members of the Bacteroidetes phylum, are significant components of the human gut microbiota, crucial for maintaining gut homeostasis. 

This phylum, constituting about 30% of the human gut microbiota, includes several genera such as Bacteroides, Prevotella, and Porphyromonas. 

The proportion of Bacteroidetes varies based on population, geography, age, and diet.

Characteristics and Taxonomy

Bacteroides spp. are gram-negative, non-spore forming, anaerobic, rod-shaped bacteria. Approximately 24 species have been identified, with Bacteroides fragilis and Bacteroides thetaiotaomicron being the most studied. 

These bacteria thrive in anaerobic conditions, utilizing complex polysaccharides for energy through fermentation. 

They possess unique genetic and metabolic features that enable efficient degradation of dietary fibers and carbohydrates, producing short-chain fatty acids (SCFAs) and other metabolites that impact host physiology.

The Bacteroides genus uses a Type VI secretion system to maintain competitive advantage in the gut. [3.] 

The T4SS in Bacteroides helps maintain competition and balance in the human gut by releasing toxins that target other bacteria, enabling these bacteria to outcompete others and stabilize the gut ecosystem, often through the transfer of these systems via mobile genetic elements among neighboring strains. [3.] 

Role in the Human Microbiome [7., 8., 18., 24.] 

Bacteroides spp. are key members of the human gut microbiome, significantly contributing to the microbial community in the colon. 

Their presence and abundance are influenced by diet, host genetics, and environmental exposures. 

Bacteroides spp. interact with other commensal bacteria and host cells, participating in complex microbial networks that regulate immune responses, nutrient metabolism, and intestinal barrier function.

Bacteroidetes, primarily found in the distal gut, possess a similar function of harvesting energy from diet through the fermentation of indigestible polysaccharides, producing short-chain fatty acids (SCFAs). [25.] 

Metabolic Contributions

In adults, Bacteroides and other Bacteroidetes produce SCFAs such as acetate, propionate, and butyrate from the fermentation of undigested dietary polysaccharides. SCFAs play crucial roles in gut health, glucose homeostasis, and lipid metabolism. 

‍Bacteroides and Prevotella are major contributors to SCFA production, especially propionate. These bacteria adapt flexibly to the gut's nutritional environment, using a wide range of dietary polysaccharides and proteins.

Despite their diversity, Bacteroidetes share a high capacity for polysaccharide utilization, aided by numerous carbohydrate-active enzymes (CAZYmes). Their metabolic flexibility allows them to switch between different substrates based on availability and competition within the gut ecosystem. [7.] 

Diet and Bacteroidetes:

Diet significantly influences Bacteroidetes levels. 

Diets rich in animal products increase Bacteroides levels, whereas plant-based diets promote a more diverse microbial community. [7., 19.] 

Overnutrition decreases Bacteroidetes, affecting energy harvest efficiency. Conversely, undernutrition and fasting can either increase or deplete Bacteroidetes levels, depending on the conditions. [7.] 

Bacteroidetes and Metabolic Diseases:

Studies show varied associations between Bacteroidetes and type 2 diabetes. The relative abundance of Bacteroidetes can affect glucose metabolism differently in individuals, influenced by diet and other factors. 

Gnotobiotic animal studies show specific Bacteroidetes species can have different effects on host metabolism. Daily dosing with Bacteroides cultures improved glucose tolerance and insulin sensitivity in mice, suggesting microbial metabolites as potential metabolic effectors.

However, high Bacteroides have also been associated with impaired glucose tolerance. Bacteroides species' levels correlate with glucose responses post-meal, emphasizing the importance of dietary context. [7.]

In one study, continuous blood glucose monitoring in 800 participants showed that the relative abundance of Bacteroidetes in stool was associated with a poor postprandial glucose response. [7.] 

However, within the phylum, many Bacteroides species correlated positively with a healthy postprandial glucose response when participants consumed diets optimized to their individual microbiota, dietary habits, and other factors. [7.] 

Overall, the effects of Bacteroidetes on glucose metabolism can vary significantly depending on dietary context and on the relative levels of Bacteroides subspecies. 

[7.] 

However, overall a healthy amount of Bacteroides seems to be beneficial for human metabolic health. [7., 10.]

Health Implications

Modulating Bacteroides metabolism through dietary interventions holds potential for restoring gut microbiota balance and promoting metabolic health. 

Imbalances in the composition of the gut microbiota, including alterations in Bacteroides spp. abundance, have been associated with numerous disease states. 

Bacteroidetes have been associated with metabolic disease, although the association between Bacteroidetes and metabolic diseases like obesity and type 2 diabetes is complex and context-dependent. [7.] 

Bacteroides has shown potential in preventing and treating non-alcoholic fatty liver disease (NAFLD) by modulating gut health.  [25.] 

By reducing liver inflammation, mitigating hepatic steatosis, and enhancing intestinal barrier function, they contribute to metabolic regulation, improve insulin resistance, and balance cytokines. 

While the mechanisms are not fully understood, Bacteroides’ ability to influence lipid metabolism and gut barrier integrity positions them as promising candidates for NAFLD therapy, although more clinical research is needed to confirm their efficacy.

What is Bacteroides barnesiae? [9.] 

Bacteroides barnesiae is a novel bacterial species originally isolated from the caecum of chickens. The strain, along with four others, was identified as belonging to the genus Bacteroides through rRNA gene sequence analysis. 

Phenotypically, Bacteroides barnesiae strains are strictly anaerobic, non-spore-forming, non-motile, Gram-negative pleomorphic rods. They form white-greyish, circular, raised, and convex colonies on EG agar, measuring 1.5–3.0 mm in diameter, and grow optimally at 37°C in the presence of bile. 

These strains do not produce indole, catalase, or urease, nor do they reduce nitrate to nitrite or liquefy gelatin. 

They produce acid from various sugars, including glucose, lactose, sucrose, maltose, salicin, d-xylose, d-cellobiose, d-mannose, and d-raffinose, with succinic and acetic acids as the major fermentation end products, and small amounts of isovaleric acid.

Its principal respiratory quinones are menaquinones (types of vitamin K, which can be produced from some microbiota) MK-10 (58–67%) and MK-11 (25–34%), with MK-9 as a minor component (2–3%). 

Bacteroides barnesiae in Health and Disease

As a relatively newer species (B. barnesiae was isolated in 2006 from chicken cecum), little research is currently available on the clinical significance of B. barnesiae in humans.  

Levels of B. barnesiae may be tested and reported as part of Bacteroidetes levels in stool tests, but individual levels of B. barnesiae are not commonly reported. Bacteroidetes is the phylum to which B. barnesiae belongs.

Laboratory Testing for Bacteroidetes Levels

Test Type, Sample Collection and Preparation

Bacteriodetes levels are assessed in stool samples.  Stool samples may be collected from the comfort of home.  

Testing may require avoidance of certain medications and/or supplements including probiotics prior to sample collection.  It is important to consult with the ordering provider for full test preparation instructions.  

Interpretation of Test Results

Optimal Levels of Bacteroidetes

It is important to consult with the laboratory company used for test interpretation.  

One lab company provides the following reference range for Bacteroidetes levels: 8.6e11 - 3.3e12  [15.]

Clinical Implications of High Bacteroidetes 

High levels of Bacteroidetes in the gut microbiome are generally associated with a healthy state and favorable metabolic outcomes. 

A high relative abundance of Bacteroidetes compared to other phyla like Firmicutes is considered essential for maintaining gut health, biodiversity, and homeostasis of metabolism, immune function, and colonization resistance.  

Bacteroidetes are considered a "keystone taxon" in the gut microbiome, and their depletion can lead to detrimental shifts in the microbial community structure.  [11., 21.]

Several studies have found an association between high Bacteroidetes levels and a lean phenotype or healthy weight.  A higher Bacteroidetes/Firmicutes ratio was associated with a lower body mass index (BMI).  [7., 10.] 

Conversely, a lower abundance of Bacteroidetes has been observed in obese individuals compared to lean individuals.  [7.] 

High levels of Bacteroidetes species like Bacteroides fragilis and B. thetaiotaomicron are considered beneficial as commensals, fermenting polysaccharides to produce short-chain fatty acids that serve as an energy source for the host. 

They also contribute to bile acid metabolism and provide colonization resistance against pathogens like Clostridioides difficile.  [21.]

Low Bacteroidetes Abundance  [1., 10., 11., 16.] 

Lower levels of Bacteroidetes have been associated with inflammatory bowel diseases (IBD) like ulcerative colitis, where specific Bacteroides species exhibit significantly lower abundance compared to healthy controls.

The loss of these species is suggested to result from disease exacerbation and may serve as potential biomarkers for disease activity.

Low Bacteroidetes levels may disrupt microbial community dynamics, favoring the overgrowth of potentially harmful bacteria and diminishing the beneficial effects of Bacteroidetes-mediated functions, such as the fermentation of dietary fibers and production of short-chain fatty acids (SCFAs).  [4.] 

Therefore, maintaining a high abundance of Bacteroidetes in the gut microbiome is generally considered a favorable state, associated with better metabolic health, a lean phenotype, and a lower risk of inflammatory conditions like IBD. 

Monitoring Bacteroidetes levels may have clinical significance in assessing gut health, disease risk, and potential therapeutic interventions aimed at restoring a balanced microbiome.

Natural Ways to Optimize Microbiome Health [6.]

A healthy diet and lifestyle are foundational for microbiome health.  

Diet and Nutrition

• Consume Diverse Foods: increase the variety of fruits, vegetables, whole grains, nuts, seeds, and legumes to promote microbial diversity.

• High-Fiber Diet: focus on fiber-rich foods to support the growth of beneficial bacteria.

• Fermented Foods: include yogurt, kefir, sauerkraut, kimchi, and other fermented foods to introduce probiotics.

• Polyphenol-Rich Foods: consume foods high in polyphenols such as berries, green tea, dark chocolate, and red wine to stimulate beneficial bacteria growth.

• Prebiotics: incorporate prebiotic-rich foods like garlic, onions, asparagus, and bananas to nourish beneficial bacteria.

Lifestyle

• Regular Exercise: engage in consistent physical activity to enhance gut microbiota diversity and composition.

• Stress Management: practice stress-reducing activities such as yoga, meditation, and mindfulness to prevent microbiota dysbiosis.

Medications and Supplements

• Probiotics: consider probiotic supplements to increase beneficial bacteria in the gut.

• Avoid Unnecessary Antibiotics: use antibiotics only when necessary to avoid disrupting the gut microbiome.

Environmental Factors

• Limit Artificial Sweeteners: avoid artificial sweeteners that can negatively affect gut microbiota.

• Healthy Sleep Patterns: maintain regular sleep patterns to support a balanced gut microbiome.

Hygiene Practices

• Avoid Over-Sanitization: limit the use of antibacterial soaps and sanitizers to maintain a healthy microbiota balance.

FAQ: Understanding Bacteroides barnesiae

Bacteroides barnesiae is a species of bacteria that is part of the Bacteroides genus, known for its role in the human gut microbiome. 

What is Bacteroides barnesiae?

Bacteroides barnesiae is a type of Gram-negative, anaerobic bacteria that belongs to the Bacteroides genus, which are part of the larger Bacteroidetes phylum. 

These bacteria are commonly found in the human gastrointestinal tract and play a vital role in maintaining gut health by aiding in the digestion of complex carbohydrates and other substances.

What is the Role of Bacteroides barnesiae in the Gut Microbiome?

Bacteroides barnesiae, like other members of the Bacteroides genus, contributes to the breakdown and fermentation of complex carbohydrates, producing short-chain fatty acids that are beneficial for gut health. 

These bacteria help maintain a balanced gut microbiome and support overall digestive health.

How is Bacteroides barnesiae Detected?

Bacteroides barnesiae can be detected through various microbiological and molecular techniques, such as stool culture, 16S rRNA gene sequencing, and metagenomics. 

These methods allow for the identification and quantification of Bacteroides barnesiae in the gut microbiome.

What Are the Benefits of Bacteroides barnesiae?

Bacteroides barnesiae helps in the digestion of complex carbohydrates, contributes to the production of beneficial short-chain fatty acids, and plays a role in protecting the gut lining.  Research is still elucidating specific health benefits of B. barnesiae.

Can Bacteroides barnesiae Be Harmful?

While Bacteroides barnesiae is generally beneficial, any imbalance in the gut microbiome can lead to an overgrowth of certain Bacteroides species, potentially contributing to conditions such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and other gastrointestinal disorders. 

However, such issues are typically associated with a broader dysbiosis rather than Bacteroides barnesiae specifically. Further research is needed to understand the implications of excessive levels of B. barnesiae in health and disease.

How Can I Support the Growth of Beneficial Bacteria?

Supporting the growth of beneficial bacteria involves:

• Eating a balanced diet rich in fiber, particularly from fruits, vegetables, and whole grains

• Including fermented foods in your diet, such as yogurt, kefir, and sauerkraut

• Avoiding excessive use of antibiotics, which can disrupt the gut microbiome

• Maintaining overall gut health through regular exercise and stress management

What Research is Being Conducted on Bacteroides barnesiae?

Current research on Bacteroides barnesiae focuses on understanding its role in the gut microbiome, its contributions to digestive health, and its potential implications in various diseases. 

Studies may also explore how modulating the levels of Bacteroides barnesiae and other gut bacteria can impact overall health and disease outcomes.

How Does Bacteroides barnesiae Interact with Other Gut Bacteria?

Bacteroides barnesiae may interact with other gut bacteria through competitive and cooperative interactions. 

In general, inter-bacterial interactions help maintain a balanced gut microbiome, where beneficial bacteria support each other's growth and function while keeping pathogenic bacteria in check.

When Should I Consult a Healthcare Provider About my Gut Microbiome?

You should consult a healthcare provider if you experience persistent digestive issues, such as abdominal pain, bloating, diarrhea, or constipation. 

A healthcare provider can evaluate your symptoms, potentially recommend microbiome testing, and suggest appropriate treatments or dietary changes to improve gut health.

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