Bacteroides dorei

Bacteroides dorei, a member of the Bacteroidetes phylum, plays a significant role in maintaining gut homeostasis and has emerged as a potential therapeutic agent for various health conditions. 

This anaerobic, gram-negative bacterium is part of the core gut microbiota and is closely related to Bacteroides vulgatus. 

Recent research has highlighted its involvement in regulating metabolic disorders, autoimmune conditions, and inflammatory diseases. 

Studies indicate that B. dorei can modulate the gut-liver axis, offering protective effects against liver cirrhosis by improving liver function and reducing hepatic fibrosis markers. 

Additionally, B. dorei shows promise in treating dysbiosis and ulcerative colitis, alleviating symptoms and restoring gut microbiota balance. 

Understanding the multifaceted roles of B. dorei in health and disease could pave the way for targeted probiotic therapies and innovative approaches to managing metabolic and inflammatory conditions.

Overview of Bacteroides spp. [1., 11., 16., 23., 25., 27., 28.] 

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. [33.] 

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. [33.] 

Role in the Human Microbiome [10., 11., 23., 28.]

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). [32.]

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. [10.] 

‍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. [10., 34.] 

Overnutrition decreases Bacteroidetes, affecting energy harvest efficiency. Conversely, undernutrition and fasting can either increase or deplete Bacteroidetes levels, depending on the conditions. [10.] 

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. [10.] 

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. [10.] 

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. [10.] 

Overall, the effects of Bacteroidetes on glucose metabolism can vary significantly depending on dietary context and on the relative levels of Bacteroides subspecies. [10.] However, overall a healthy amount of Bacteroides seems to be beneficial for human metabolic health. [10., 13.]

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. [10.] 

Bacteroides has shown potential in preventing and treating non-alcoholic fatty liver disease (NAFLD) by modulating gut health.  [32.] 

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 dorei?

B. dorei is an anaerobic, gram-negative rod that typically resides in the human and animal gastrointestinal tract. It is a part of the core indigenous microbiota in humans. [12.] 

B. dorei is closely related to Bacteroides vulgatus, making it difficult to distinguish between the two using conventional methods like MALDI-TOF MS. 16S rRNA gene sequencing is necessary for accurate identification. [12.] 

Despite its relatively recent discovery in 2006, B. dorei has been implicated in several health conditions. [12.] 

Autoimmunity

In an article investigating the role of Bacteroides dorei in the gut microbiome of Finnish children at high genetic risk for type 1 diabetes (T1D), it was found that B. dorei, along with Bacteroides vulgatus, was significantly more abundant in children who developed T1D autoimmunity compared to healthy controls. [7.] 

This increase in B. dorei coincided with the introduction of solid foods, indicating that dietary factors might influence its abundance. 

The findings imply that B. dorei could serve as a potential biomarker for early T1D prediction in genetically susceptible infants.

Obesity and Metabolic Disorders

The gut microbiome, particularly Bacteroides members including Bacteroides dorei, may play important roles in regulating obesity and associated metabolic disorders. [29.] 

One study demonstrated that Bacteroides dorei, along with Bacteroides vulgatus, mitigates body weight gain in diet-induced obesity (DIO) mice through its ability to regulate brown adipose tissue (BAT) branched-chain amino acid (BCAA) catabolism. [29.] 

This improvement in BAT BCAA catabolism enhances BAT thermogenesis, reduces systemic glucose intolerance, and lowers adiposity. 

The anti-inflammatory effects of Bacteroides spp. play a crucial role in this process by suppressing BAT inflammation, particularly TNF-α production, and macrophage accumulation, which are key contributors to BCAA catabolic defects in BAT. [29.]

Clinically, these findings suggest that modulating the gut microbiome through supplementation with Bacteroides dorei could be part of an effective strategy for treating obesity. [29.] 

Overall, there is a general trend in research of decreased Bacteroides abundance in obese individuals. [2.] 

Dysbiosis and Inflammatory Bowel Diseases

Some research shows that Bacteroides dorei may have a protective role in treating dysbiosis and ulcerative colitis (UC). [6.] 

B. dorei is found in significantly higher amounts in healthy individuals compared to those with UC, suggesting it has a protective role. [6.] 

In a mouse model of UC, B. dorei alleviated symptoms such as colon contraction, intestinal bleeding, and mucosal damage. Additionally, B. dorei F18-22 improved gut microbiota balance by increasing the abundance of anti-inflammatory Eubacterium siraeum and decreasing pro-inflammatory bacteria like Escherichia-Shigella spp. [6.] 

B. dorei F18-22 was well tolerated in mice, showing no toxicity after 28 days of daily administration, indicating its safety as a probiotic. [6.] 

Liver Cirrhosis

B. dorei was shown to benefit liver function in male mice with liver cirrhosis, including improvements in hepatic fibrosis markers. [17.] 

Laboratory Testing for Bacteroides dorei

Test Type, Sample Collection and Preparation

Bacteroides dorei 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 Bacteroides dorei

It is important to consult with the laboratory company used for test interpretation.  Bacteroides levels are typically assessed by species, although some lesser-known species, such as Bacteroides dorei, may be reported as part of Bacteroides spp.  

One lab company provides the following reference range for Bacteroides spp. levels alongside Prevotella spp., and reports this on a scale from -3 (low prevalence of these organisms) to +3 (high prevalence of these organisms).  [20.]

Clinical Implications of High Bacteroides 

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

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

Bacteroidetes, the phylum of which Bacteroides are a part, are considered a "keystone taxon" in the gut microbiome, and their depletion can lead to detrimental shifts in the microbial community structure.  [14., 25.]

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).  [10., 13.] 

Conversely, a lower abundance of Bacteroidetes has been observed in obese individuals compared to lean individuals.  [10.] 

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.  [25.]

However, elevated levels of Bacteroides in the setting of digestive symptoms or pathology warrants further assessment for bacterial strains such as B. fragilis or B. caccae, which have been associated with digestive pathology in certain settings.  

Low Bacteroides Abundance  [1., 13., 14.,21.]

Lower levels of Bacteroides 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 Bacteroides levels may disrupt microbial community dynamics, favoring the overgrowth of potentially harmful bacteria and diminishing the beneficial effects of Bacteroides-mediated functions, such as the fermentation of dietary fibers and production of short-chain fatty acids (SCFAs).  [5.] 

Therefore, maintaining a relatively high abundance of Bacteroides 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 Bacteroides 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 [9.]

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 dorei

Bacteroides dorei is a species of bacteria that is part of the human gut microbiome. This FAQ section addresses common questions about Bacteroides dorei, its significance, and its role in health and disease.

What is Bacteroides dorei?

Bacteroides dorei is a type of Gram-negative, anaerobic bacterium that belongs to the Bacteroides genus. It is commonly found in the human gastrointestinal tract, where it plays a role in the digestion of complex carbohydrates and helps maintain a healthy gut microbiome.

What Is the Role of Bacteroides dorei in the Gut Microbiome?

Bacteroides dorei contributes to the breakdown and fermentation of complex carbohydrates in the gut. By producing short-chain fatty acids and other metabolites, it supports gut health and influences various metabolic processes.

How is Bacteroides dorei Detected?

Bacteroides dorei can be detected using microbiological and molecular techniques such as stool culture, 16S rRNA gene sequencing, and metagenomic analysis. These methods allow for the identification and quantification of Bacteroides dorei in the gut microbiome.

What Are the Benefits of Bacteroides dorei?

The benefits of Bacteroides dorei include aiding in the digestion of complex carbohydrates, producing beneficial short-chain fatty acids, supporting the gut barrier function, and helping to maintain a balanced gut microbiome.

It may support liver function and a healthy metabolism.  

Can Bacteroides dorei Be Harmful?

Under normal circumstances, Bacteroides dorei is beneficial and contributes to a healthy gut. 

However, an imbalance in the gut microbiome (dysbiosis) can lead to overgrowth of certain bacteria, including Bacteroides dorei.

How Does Bacteroides dorei Interact with Other Gut Bacteria?

Bacteroides dorei interacts with other gut bacteria through competitive and cooperative relationships. These interactions help maintain a balanced gut microbiome, where beneficial bacteria support each other's growth and function while keeping pathogenic bacteria in check.

How Can I Support the Growth of Beneficial Bacteria Like Bacteroides dorei?

Supporting the growth of beneficial bacteria like Bacteroides dorei involves:

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

• Consuming fermented foods such as yogurt, kefir, and sauerkraut

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

• Maintaining a healthy lifestyle with regular exercise and stress management

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.

How Can I Stay Informed About Research and Developments Related to Bacteroides dorei?

Stay informed by following scientific publications, attending relevant conferences, and monitoring updates from research institutions and health organizations. Journals focused on microbiology, gastroenterology, and health research often publish the latest findings on Bacteroides dorei and the gut microbiome.

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