Fibrobacter sp. HC4, a newly isolated strain, demonstrates a high cellulolytic activity as revealed by enzymatic measurements and in vitro assay.
Abstract: Despite their low quantity and abundance, the cellulolytic bacteria that inhabit the equine large intestine are vital to their host, as they enable the crucial use of forage-based diets. Fibrobacter succinogenes is one of the most important intestinal cellulolytic bacteria. In this study, Fibrobacter sp. HC4, one cellulolytic strain newly isolated from the horse cecum, was characterized for its ability to utilize plant cell wall fibers. Fibrobacter sp. HC4 consumed only cellulose, cellobiose, and glucose and produced succinate and acetate in equal amounts. Among genes coding for CAZymes, 26% of the detected glycoside hydrolases (GHs) were involved in cellulolysis. These cellulases belong to the GH5, GH8, GH9, GH44, GH45, and GH51 families. Both carboxymethyl cellulase and xylanase activities of Fibrobacter sp. HC4 were detected using the Congo red method and were higher than those of F. succinogenes S85, the type strain. The in vitro addition of Fibrobacter sp. HC4 to a fecal microbial ecosystem of horses with large intestinal acidosis significantly enhanced fibrolytic activity as measured by the increase in gas and volatile fatty acids production during the first 48 h. According to this, the pH decreased and the disappearance of dry matter increased at a faster rate with Fibrobacter sp. HC4. Our data suggest a high specialization of the new strain in cellulose degradation. Such a strain could be of interest for future exploitation of its probiotic potential, which needs to be further determined by in vivo studies.IMPORTANCECellulose is the most abundant of plant cell wall fiber and can only be degraded by the large intestine microbiota, resulting in the production of volatile fatty acids that are essential for the host nutrition and health. Consequently, cellulolytic bacteria are of major importance to herbivores. However, these bacteria are challenged by various factors, such as high starch diets, which acidify the ecosystem and reduce their numbers and activity. This can lead to an imbalance in the gut microbiota and digestive problems such as colic, a major cause of mortality in horses. In this work, we characterized a newly isolated cellulolytic strain, Fibrobacter sp. HC4, from the equine intestinal microbiota. Due to its high cellulolytic capacity, reintroduction of this strain into an equine fecal ecosystem stimulates hay fermentation in vitro. Isolating and describing cellulolytic bacteria is a prerequisite for using them as probiotics to restore intestinal balance.
Publication Date: 2024-07-31 PubMed ID: 39082812PubMed Central: PMC11337828DOI: 10.1128/aem.00514-24Google Scholar: Lookup
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Summary
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The research focuses on a newly isolated bacteria strain named Fibrobacter sp. HC4 which has been proven to have high cellulolytic activity, meaning it breaks down cellulose effectively. This could be beneficial for horses on high-starch diets, which often lead to digestive issues due to a reduction in the normal cellulolytic bacteria in the gut.
Importance of Cellulosic Bacteria in Equine Gut
- The researchers highlight the importance of cellulolytic bacteria in the equine large intestine, despite their small quantity and abundance, primarily for enabling the efficient use of forage-based diets.
- Equine health can be significantly impacted by imbalances in cellulolytic bacteria, often resulting in digestive issues such as colic, a leading cause of equine mortality. Cellulolytic imbalances can be brought on by factors like high-starch diets, which both acidify the microbiotic ecosystem and reduce existing bacteria numbers and activity level.
Detailed Insights on Fiberobacter sp. HC4
- The Fibrobacter sp. HC4 strain, derived from the horse cecum, was found to only consume cellulose, cellobiose, and glucose, while producing succinate and acetate in equal quantities.
- Of the enzymes coded by this strain, 26% were glycoside hydrolases (GHs) involved directly in cellulolysis or the breakdown of cellulose. The cellulases from this strain belonged to six identified families: GH5, GH8, GH9, GH44, GH45, and GH51.
- The enzymatic activity of Fibrobacter sp. HC4, specifically its carboxymethyl cellulase and xylanase activities, were reportedly higher than those of Fibrobacter sp. S85, the standard strain.
Potential Use of Fiberobacter sp. HC4 as a Probiotic
- Adding this newly isolated strain to the fecal microbiotic ecosystem of horses with significant intestinal acidosis showed noticeable improvement in fibrolytic activity. This was measured by an increase in gas and volatile fatty acid production in the initial 48 hours.
- Promising results such as a decrease in pH levels and a quickened rate of dry matter disappearance were also observed with the use of Fibrobacter sp. HC4, implying the strain’s strong specialization in cellulose degradation.
- The authors suggest that these properties make Fibrobacter sp. HC4 of interest for future study and potential use as a probiotic to restore gut health in horses and other herbivores. However, more in vivo studies are required to determine the full potential of this strain.
Cite This Article
APA
Froidurot A, Jacotot E, Julliand S, Grimm P, Julliand V.
(2024).
Fibrobacter sp. HC4, a newly isolated strain, demonstrates a high cellulolytic activity as revealed by enzymatic measurements and in vitro assay.
Appl Environ Microbiol, 90(8), e0051424.
https://doi.org/10.1128/aem.00514-24 Publication
Researcher Affiliations
- Univ. Bourgogne Franche-Comté, L'Institut Agro Dijon, PAM UMR A 02.102, Dijon, France.
- Univ. Bourgogne Franche-Comté, L'Institut Agro Dijon, PAM UMR A 02.102, Dijon, France.
- Lab To Field, Dijon, France.
- Lab To Field, Dijon, France.
- Univ. Bourgogne Franche-Comté, L'Institut Agro Dijon, PAM UMR A 02.102, Dijon, France.
MeSH Terms
- Animals
- Cellulose / metabolism
- Fibrobacter / genetics
- Fibrobacter / enzymology
- Fibrobacter / isolation & purification
- Fibrobacter / metabolism
- Horses
- Feces / microbiology
- Cellulase / metabolism
- Cellulase / genetics
- Cecum / microbiology
- Bacterial Proteins / genetics
- Bacterial Proteins / metabolism
- Gastrointestinal Microbiome
- Glycoside Hydrolases / metabolism
- Glycoside Hydrolases / genetics
- Cellobiose / metabolism
Grant Funding
- FEDER-FSE
Conflict of Interest Statement
The authors declare no conflict of interest.
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This article has been cited 3 times.- Dockman RL, Ottesen EA. Niche specialization and cross-feeding interactions shaping gut microbial fiber degradation in a model omnivore. bioRxiv 2026 Jan 22;.
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