{"title":"<i>Fibrobacter</i> sp. HC4, a newly isolated strain, demonstrates a high cellulolytic activity as revealed by enzymatic measurements and <i>in vitro</i> assay.","authors":"Alicia Froidurot, Emmanuel Jacotot, Samy Julliand, Pauline Grimm, Véronique Julliand","doi":"10.1128/aem.00514-24","DOIUrl":null,"url":null,"abstract":"<p><p>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. <i>Fibrobacter succinogenes</i> is one of the most important intestinal cellulolytic bacteria. In this study, <i>Fibrobacter</i> sp. HC4, one cellulolytic strain newly isolated from the horse cecum, was characterized for its ability to utilize plant cell wall fibers. <i>Fibrobacter</i> 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 <i>Fibrobacter</i> sp. HC4 were detected using the Congo red method and were higher than those of <i>F. succinogenes</i> S85, the type strain. The <i>in vitro</i> addition of <i>Fibrobacter</i> 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 <i>Fibrobacter</i> 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 <i>in vivo</i> 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, <i>Fibrobacter</i> 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 <i>in vitro</i>. Isolating and describing cellulolytic bacteria is a prerequisite for using them as probiotics to restore intestinal balance.</p>","PeriodicalId":8002,"journal":{"name":"Applied and Environmental Microbiology","volume":null,"pages":null},"PeriodicalIF":3.9000,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11337828/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Applied and Environmental Microbiology","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1128/aem.00514-24","RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/7/31 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"BIOTECHNOLOGY & APPLIED MICROBIOLOGY","Score":null,"Total":0}
引用次数: 0
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.
期刊介绍:
Applied and Environmental Microbiology (AEM) publishes papers that make significant contributions to (a) applied microbiology, including biotechnology, protein engineering, bioremediation, and food microbiology, (b) microbial ecology, including environmental, organismic, and genomic microbiology, and (c) interdisciplinary microbiology, including invertebrate microbiology, plant microbiology, aquatic microbiology, and geomicrobiology.