Bacteroides cellulosilyticus

Bacteroides cellulosilyticus, a member of the Bacteroidetes phylum, is a significant component of the human gut microbiota, playing a crucial role in maintaining gut homeostasis. 

This gram-negative, non-motile, and strictly anaerobic bacterium thrives optimally at 37°C and a pH of 6.8, efficiently degrading cellulose and various sugars into short-chain fatty acids (SCFAs) such as acetate, propionate, and succinate. 

Its unique ability to metabolize complex polysaccharides distinguishes B. cellulosilyticus from other Bacteroides species. 

Recent research highlights its impact on gut health, indicating that its presence in the gut is associated with metabolic health and influences weight management and liver conditions. For instance, reduced levels of B. cellulosilyticus are observed in patients with liver cirrhosis and IBD, suggesting its potential role as a biomarker for these conditions. 

Given its importance in fermenting dietary fibers and producing beneficial SCFAs, maintaining a balanced abundance of B. cellulosilyticus is essential for overall metabolic health and disease prevention.

Overview of Bacteroides spp. [1., 8., 12., 18., 20., 22., 23.] 

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. [26.] 

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. [26.] 

Role in the Human Microbiome [8., 18., 23.] 

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). [27.] 

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., 28.] 

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., 9.]

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.  [27.] 

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 cellulosilyticus?

Bacteroides cellulosilyticus: Characteristics and Significance

Bacteroides cellulosilyticus is a gram-negative, non-motile, strictly anaerobic organism, requiring an oxygen-free medium for growth. It grows optimally at 37°C and pH 6.8, with a growth range between 30–39°C and pH 6.5–7.2. [14.] 

The bacterium does not produce catalase or cytochrome oxidase and does not form heat-resistant endospores. [14.] 

‍B. cellulosylyticus’s primary role seems to revolve around its processing of fibers and carbohydrates.  The greatest number of glycan degrading enzymes, 510 CAZYmes, has so far been attributed to B. cellulosilyticus. [7.] 

It metabolizes cellulose and various sugars, converting them mainly to acetate, propionate, and succinate, with smaller amounts of formate and lactate also produced. Substrates used include glucose, sucrose, fructose, maltose, xylose, galactose, ribose, melibiose, mannose, lactulose, galacturonic acids, pectin, starch, and cellulose. [14.]

B. cellulosilyticus is the only Bacteroides species from the human gut that has been reported to degrade cellulose effectively. [14.] Its key role in the degradation of cellulose and other polysaccharides in the human gut contributes to the overall process of fermentation and organic matter breakdown. [14.] 

Recent research utilizing non-targeted metabolomics in human urine has identified B. cellulosyliticus as a key player in producing various metabolites linked to gut health. [24.] 

One study revealed that bowel evacuation, which significantly depletes the fecal microbiome, affects levels of 331 metabolite ions in urine, including those modified through processes like glucuronidation and sulfation. [24.] 

These metabolites, including amino acids and organic acids, suggest that B. cellulosyliticus significantly influences the host's metabolic pathways, emphasizing its importance in gut health and its potential impact on diseases related to gut microbiota imbalances. [24.] 

Correlation with Weight Gain and Obesity [3.] 

Studies have shown a correlation between Bacteroides cellulosilyticus levels and weight gain or obesity. In a controlled intervention trial, overweight subjects with a low Prevotella-to-Bacteroides (P/B) ratio gained weight after consuming arabinoxylan-oligosaccharides (AXOS) from wheat bran, while those with a high P/B ratio did not experience weight changes. 

The relative abundance of B. cellulosilyticus exhibited the highest positive correlation with weight gain after AXOS consumption. [3.] 

Association with Liver Cirrhosis

Bacteroides cellulosilyticus has also been implicated in liver health. 

The fecal microbiota of Hepatitis B liver cirrhosis (HBLC) patients showed a significant reduction in Bacteroidetes, making up only 4% of their gut microbiota compared to 53% in healthy individuals. [19.] 

This included a notable absence of several species including Bacteroides cellulosilyticus. [19.] 

There was also a substantial increase in Proteobacteria in the cirrhotic patients, constituting 43% of their microbiota compared to only 4% in the healthy controls. Specifically, opportunistic pathogens like Escherichia coli, Klebsiella pneumonia, and Enterobacter cloaca were enriched. [19.] 

Laboratory Testing for Bacteroides cellulosilyticus

Test Type, Sample Collection and Preparation

Bacteroides cellulosilyticus 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 cellulosilyticus

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 cellulosilyticus, 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).  [15.]

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.  [10.,20.]

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., 9.] 

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

Contrary to this, some specific research including Bacteroides cellulosilyticus demonstrated that increased levels of this organism were associated with weight gain.  This illustrates the nuanced nature of digestive health.  

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.  [20.]

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., 9., 10., 16.] 

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).  [4.] 

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.

Treatments for B. cellulosilyticus

Common Antibiotic Therapies [5.] 

Treatments for Bacteroides infections commonly center on treatment for B. fragilis infections, which is the most common organism associated with serious Bacteroides infections.  

Bacteroides spp. can cause serious infections if it breaches the mucosal barrier due to inflammation, trauma, or surgery. Proper specimen collection and prompt lab processing are crucial to avoid contamination. 

‍Bacteroides spp. are part of the normal colon flora but can cause significant morbidity when the mucosal lining is breached.  This is frequently seen in infections post-surgery or trauma, and in patients with malignancies. 

The bacterium is resistant to penicillin due to beta-lactamase production, with effective antibiotics including metronidazole, Piperacillin/tazobactam, and meropenem. 

However, resistance to metronidazole is emerging, with mechanisms involving nim genes, while newer antibiotics like eravacycline and tazobactam/ceftolozane show promise in treating complex infections.

The overall mortality rate for Bacteroides fragilis bacteremia is high, particularly in patients with comorbid conditions like malignancy, and complications can include sepsis and abscess formation in various tissues. 

In conclusion, while Bacteroides fragilis is normally harmless in the colon, it can cause serious infections if it spreads to other tissues. Prompt evaluation, appropriate antibiotic use, and interprofessional management are crucial to improving patient outcomes.

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 cellulosilyticus

Bacteroides cellulosilyticus is a species of bacteria that plays an important role in the human gut microbiome and environmental ecosystems. This FAQ section addresses common questions about Bacteroides cellulosilyticus, its significance, and its role in health and environmental processes.

What is Bacteroides cellulosilyticus?

Bacteroides cellulosilyticus is a type of Gram-negative, anaerobic bacterium that belongs to the Bacteroides genus. 

It is known for its ability to break down complex carbohydrates, particularly cellulose, making it an important player in the digestive processes of the human gut and environmental decomposition.

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

In the gut microbiome, Bacteroides cellulosilyticus helps in the digestion of complex carbohydrates, including cellulose, which the human body cannot break down on its own. 

By decomposing these carbohydrates, it produces short-chain fatty acids that are beneficial for gut health and overall metabolic functions.

How is Bacteroides cellulosilyticus Detected?

Bacteroides cellulosilyticus can be detected using various 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 cellulosilyticus in the gut microbiome or environmental samples.

What Are the Benefits of Bacteroides cellulosilyticus?

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

Can Bacteroides cellulosilyticus Be Harmful?

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

However, an imbalance in the gut microbiome (dysbiosis) can sometimes lead to an overgrowth of Bacteroides species, potentially contributing to gastrointestinal disorders such as inflammatory bowel disease (IBD) or weight gain.

How Does Bacteroides cellulosilyticus Contribute to Environmental Processes?

In the environment, Bacteroides cellulosilyticus plays a role in the decomposition of plant material, particularly cellulose. 

This process is essential for nutrient cycling and maintaining soil health. The bacterium's ability to break down complex carbohydrates makes it valuable in composting and waste treatment processes.

How Can I Support the Growth of Beneficial Bacteria like Bacteroides cellulosilyticus?

Supporting the growth of beneficial bacteria like Bacteroides cellulosilyticus involves:

• Eating a balanced diet rich in dietary fiber, especially 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

How does Bacteroides cellulosilyticus interact with other gut bacteria?

Bacteroides cellulosilyticus 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.

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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