Pub Date : 2025-02-01DOI: 10.1016/j.anaerobe.2025.102939
Benjamin Lewis , Adenrele Oludiran , Ann Progulske-Fox , William Dunn
The probing of live bacteria via the incorporation of fluorescent D-amino acids (FDAAs) during peptidoglycan synthesis has been shown to be practical for visualizing both gram-positive and gram-negative bacterial species. This study demonstrates the reliability and applications of FDAA labelling for the fluorescent imaging of an obligate anaerobe.
{"title":"Labelling of a live obligate anaerobe using fluorescent D-amino acids","authors":"Benjamin Lewis , Adenrele Oludiran , Ann Progulske-Fox , William Dunn","doi":"10.1016/j.anaerobe.2025.102939","DOIUrl":"10.1016/j.anaerobe.2025.102939","url":null,"abstract":"<div><div>The probing of live bacteria via the incorporation of fluorescent D-amino acids (FDAAs) during peptidoglycan synthesis has been shown to be practical for visualizing both gram-positive and gram-negative bacterial species. This study demonstrates the reliability and applications of FDAA labelling for the fluorescent imaging of an obligate anaerobe.</div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"91 ","pages":"Article 102939"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142998883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.anaerobe.2024.102924
Yanyan Wang , Juan Wen , Binxin Guo , Wenqi Zheng , Junrui Wang
Objective
Strains of carbapenem-resistant Bacteroides fragilis have frequently emerged in recent years. In China, data on the genotypic and phenotypic characteristics of these antimicrobial-resistant anaerobic bacteria are scarce. Thus, the aim of this study was to characterize clinical isolates of carbapenem-resistant B. fragilis collected from a tertiary hospital in China using whole genome sequencing (WGS), phenotypic susceptibility tests, and a biofilm formation assay.
Methods
We analyzed 49 B. fragilis strains with different antimicrobial resistance profiles. Antimicrobial susceptibility was determined using the agar dilution method and biofilm formation using a crystal violet assay. Genomic characteristics were analyzed using WGS, and the transcription level of cfiA, which is responsible for carbapenem resistance, was determined using quantitative reverse transcription polymerase chain reaction (PCR). Carbapenem-sensitive isolates were used as controls.
Results
All 49 B. fragilis isolates were biofilm producers and the percentage of carbapenem-resistant isolates was 42.86 % (21/49). The percentage of carbapenem-resistant isolates with medium-to-strong biofilm production ability was significantly lower than that of carbapenem-sensitive isolates (19.1 % vs. 88.9 %, p < 0.01). None of the carbapenem-resistant B. fragilis isolates carried bft. In contrast, 53.6 % (15/28) of the carbapenem-sensitive isolates carried bft, and all of them were fpn(+). All carbapenem-resistant isolates (21/21, 100 %) harbored cfiA and its upstream insertion sequence (IS) element. Three isolates (BF058, BF059, and BF060) carried the IS613 element, which was not immediately adjacent upstream to cfiA but was separated by a 1000-kb sequence encoding vatD. The quantitative PCR assay results revealed the elevated expression of cfiA mRNA among carbapenem-resistant isolates, although the relative expression levels varied greatly among isolates. However, a significant correlation between the relative expression level of cfiA mRNA and phenotypic carbapenem resistance was observed.
Conclusions
Carbapenem-resistant B. fragilis isolates carried a low frequency of virulence-related genes and showed weaker biofilm formation ability compared with carbapenem-sensitive B. fragilis isolates. CfiA was the dominant mediator of carbapenem resistance in B. fragilis. This study was the first to identify the structural plasticity of the cfiA-IS element, emphasizing the diverse and complex evolution of carbapenem resistance in B. fragilis, which warrants further investigation.
{"title":"Genotypic and phenotypic diversity of carbapenem-resistant Bacteroides fragilis strains collected from different clinical origins","authors":"Yanyan Wang , Juan Wen , Binxin Guo , Wenqi Zheng , Junrui Wang","doi":"10.1016/j.anaerobe.2024.102924","DOIUrl":"10.1016/j.anaerobe.2024.102924","url":null,"abstract":"<div><h3>Objective</h3><div>Strains of carbapenem-resistant <em>Bacteroides fragilis</em> have frequently emerged in recent years. In China, data on the genotypic and phenotypic characteristics of these antimicrobial-resistant anaerobic bacteria are scarce. Thus, the aim of this study was to characterize clinical isolates of carbapenem-resistant <em>B. fragilis</em> collected from a tertiary hospital in China using whole genome sequencing (WGS), phenotypic susceptibility tests, and a biofilm formation assay.</div></div><div><h3>Methods</h3><div>We analyzed 49 <em>B. fragilis</em> strains with different antimicrobial resistance profiles. Antimicrobial susceptibility was determined using the agar dilution method and biofilm formation using a crystal violet assay. Genomic characteristics were analyzed using WGS, and the transcription level of <em>cfiA</em>, which is responsible for carbapenem resistance, was determined using quantitative reverse transcription polymerase chain reaction (PCR). Carbapenem-sensitive isolates were used as controls.</div></div><div><h3>Results</h3><div>All 49 <em>B. fragilis</em> isolates were biofilm producers and the percentage of carbapenem-resistant isolates was 42.86 % (21/49). The percentage of carbapenem-resistant isolates with medium-to-strong biofilm production ability was significantly lower than that of carbapenem-sensitive isolates (19.1 % vs. 88.9 %, <em>p</em> < 0.01). None of the carbapenem-resistant <em>B. fragilis</em> isolates carried <em>bft</em>. In contrast, 53.6 % (15/28) of the carbapenem-sensitive isolates carried <em>bft</em>, and all of them were <em>fpn</em>(+). All carbapenem-resistant isolates (21/21, 100 %) harbored <em>cfiA</em> and its upstream insertion sequence (IS) element. Three isolates (BF058, BF059, and BF060) carried the IS613 element, which was not immediately adjacent upstream to <em>cfiA</em> but was separated by a 1000-kb sequence encoding <em>vatD</em>. The quantitative PCR assay results revealed the elevated expression of <em>cfiA</em> mRNA among carbapenem-resistant isolates, although the relative expression levels varied greatly among isolates. However, a significant correlation between the relative expression level of <em>cfiA</em> mRNA and phenotypic carbapenem resistance was observed.</div></div><div><h3>Conclusions</h3><div>Carbapenem-resistant <em>B. fragilis</em> isolates carried a low frequency of virulence-related genes and showed weaker biofilm formation ability compared with carbapenem-sensitive <em>B. fragilis</em> isolates. <em>CfiA</em> was the dominant mediator of carbapenem resistance in <em>B. fragilis</em>. This study was the first to identify the structural plasticity of the <em>cfiA</em>-IS element, emphasizing the diverse and complex evolution of carbapenem resistance in <em>B. fragilis</em>, which warrants further investigation.</div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"91 ","pages":"Article 102924"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142791057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.anaerobe.2025.102942
Christiane Gruetzmacher , Marilena Nakaguma , Raquel Soares Jallad , Flora Ladeira Craveiro , Ana Paula da Silva Tenorio , Mario Padula , Rafael Loch Batista
Lemierre's syndrome (LS) is a rare complication of oropharyngeal infections, often causing sepsis, internal jugular vein thrombosis, and metastatic infections. We present a unique case of a 48-year-old male with LS complicated by an internal carotid artery pseudoaneurysm compressing the pituitary gland, resulting in panhypopituitarism. Diagnosis was confirmed via imaging and detection of Fusobacterium nucleatum. Treatment included antibiotics, anticoagulation, and hormone replacement. Although the patient recovered from pituitary deficiencies, growth hormone deficiency persisted. This case emphasizes the importance of recognizing endocrine dysfunctions in LS and highlights the need for multidisciplinary management to address vascular and neuroendocrine complications.
{"title":"Hypopituitarism secondary to internal carotid artery pseudoaneurysm following Lemierre's syndrome caused by Fusobacterium nucleatum","authors":"Christiane Gruetzmacher , Marilena Nakaguma , Raquel Soares Jallad , Flora Ladeira Craveiro , Ana Paula da Silva Tenorio , Mario Padula , Rafael Loch Batista","doi":"10.1016/j.anaerobe.2025.102942","DOIUrl":"10.1016/j.anaerobe.2025.102942","url":null,"abstract":"<div><div>Lemierre's syndrome (LS) is a rare complication of oropharyngeal infections, often causing sepsis, internal jugular vein thrombosis, and metastatic infections. We present a unique case of a 48-year-old male with LS complicated by an internal carotid artery pseudoaneurysm compressing the pituitary gland, resulting in panhypopituitarism. Diagnosis was confirmed via imaging and detection of <em>Fusobacterium nucleatum</em>. Treatment included antibiotics, anticoagulation, and hormone replacement. Although the patient recovered from pituitary deficiencies, growth hormone deficiency persisted. This case emphasizes the importance of recognizing endocrine dysfunctions in LS and highlights the need for multidisciplinary management to address vascular and neuroendocrine complications.</div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"92 ","pages":"Article 102942"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143122029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Paeniclostridium sordellii is responsible for severe infections in horses, cattle, and sheep, however, conventional vaccines exhibit limitations in production and immunogenicity. This study assessed the immunogenicity of a recombinant bacterin composed of a chimera (rQTcsHL) that combines segments from the lethal (TcsL) and hemorrhagic (TcsH) toxins in mice and sheep. Both immunized animal groups exhibited elevated levels of IgG, with the mice demonstrating moderate protection (<50 %) against lethal challenges, comparable to that of the conventional vaccine. Further molecular optimization is essential to enhance its efficacy.
{"title":"Immunogenicity of a recombinant chimera composed of CROP domain segments from the hemorrhagic and lethal toxins of Paeniclostridium sordellii","authors":"Rafael Rodrigues Rodrigues , Neida Conrad , Marcos Roberto Alves Ferreira , Clóvis Moreira Júnior , Mariliana Luiza Ferreira Alves , Pamela Aristimunho Sedrez , Vitória Müller , Alessandra Neis , Miguel Andrade Bilhalva , Cleideanny Cancela Galvão , Fábio Pereira Leivas Leite , Fabricio Rochedo Conceição","doi":"10.1016/j.anaerobe.2025.102938","DOIUrl":"10.1016/j.anaerobe.2025.102938","url":null,"abstract":"<div><div><em>Paeniclostridium sordellii</em> is responsible for severe infections in horses, cattle, and sheep, however, conventional vaccines exhibit limitations in production and immunogenicity. This study assessed the immunogenicity of a recombinant bacterin composed of a chimera (rQTcsHL) that combines segments from the lethal (TcsL) and hemorrhagic (TcsH) toxins in mice and sheep. Both immunized animal groups exhibited elevated levels of IgG, with the mice demonstrating moderate protection (<50 %) against lethal challenges, comparable to that of the conventional vaccine. Further molecular optimization is essential to enhance its efficacy.</div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"91 ","pages":"Article 102938"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142963283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Parvimonas micra is a gram-positive coccus which is an obligate anaerobe. It is a commensal in the oropharyngeal cavity and the gastrointestinal tract. The genus Parvimonas has only a single species, P. micra. Although there are several reports of infections due to P. micra involving various body sites, cases of brain abscess due to this organism have been under-reported in the literature. Here we present a rare case of cerebellar abscess caused by P. micra in a nine-year-old boy with complex cyanotic heart disease.
{"title":"A rare isolation of Parvimonas micra from cerebellar abscess in a patient with complex cyanotic heart disease","authors":"Praveen Ravichandran , Ramit Kundu , Rakhi Biswas , Sathiaprabhu Anbazhagan","doi":"10.1016/j.anaerobe.2025.102943","DOIUrl":"10.1016/j.anaerobe.2025.102943","url":null,"abstract":"<div><div><em>Parvimonas micra</em> is a gram-positive coccus which is an obligate anaerobe. It is a commensal in the oropharyngeal cavity and the gastrointestinal tract. The genus <em>Parvimonas</em> has only a single species, <em>P. micra</em>. Although there are several reports of infections due to <em>P. micra</em> involving various body sites, cases of brain abscess due to this organism have been under-reported in the literature. Here we present a rare case of cerebellar abscess caused by <em>P. micra</em> in a nine-year-old boy with complex cyanotic heart disease<strong>.</strong></div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"93 ","pages":"Article 102943"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143078484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.anaerobe.2024.102920
Md Kamrul Hasan, Oluchi Alaribe, Revathi Govind
Clostridioides difficile has been recognized as an important nosocomial pathogen that causes diarrheal disease as a consequence of antibiotic exposure and costs the healthcare system billions of dollars every year. C. difficile enters the host gut as dormant spores, germinates into vegetative cells, colonizes the gut, and produces toxins TcdA and/or TcdB, leading to diarrhea and inflammation. Spores are the primary transmission vehicle, while the toxins A and B directly contribute to the disease. Thus, toxin production and sporulation are the key traits that determine the success of C. difficile as a pathogen. Both toxins and spores are produced during the late stationary phase in response to various stimuli. This review provides a comprehensive analysis of the current knowledge on the molecular mechanisms, highlighting the regulatory pathways that interconnect toxin gene expression and sporulation in C. difficile. The roles of carbohydrates, amino acids and other nutrients and signals, in modulating these virulence traits through global regulatory networks are discussed. Understanding the links within the gene regulatory network is crucial for developing effective therapeutic strategies against C. difficile infections, potentially leading to targeted interventions that disrupt the co-regulation of toxin production and sporulation.
艰难梭菌已被公认为一种重要的院内病原体，它因接触抗生素而导致腹泻，每年给医疗系统造成数十亿美元的损失。艰难梭菌以休眠孢子的形式进入宿主肠道，发芽成为无性细胞，在肠道内定植，并产生毒素 TcdA 和/或 TcdB，导致腹泻和炎症。孢子是主要的传播媒介，而毒素 A 和毒素 B 则直接导致疾病。因此，产生毒素和孢子是决定艰难梭菌能否成为病原体的关键特征。在静止后期，毒素和孢子都会在各种刺激下产生。本综述全面分析了有关分子机制的现有知识，重点介绍了艰难梭菌毒素基因表达和孢子产生之间的调控途径。文中讨论了碳水化合物、氨基酸和其他营养物质及信号在通过全球调控网络调节这些毒力特征方面的作用。了解基因调控网络内部的联系对于开发针对艰难梭菌感染的有效治疗策略至关重要，有可能导致有针对性的干预措施，破坏毒素生产和孢子生成的共同调控。
{"title":"Regulatory networks: Linking toxin production and sporulation in Clostridioides difficile","authors":"Md Kamrul Hasan, Oluchi Alaribe, Revathi Govind","doi":"10.1016/j.anaerobe.2024.102920","DOIUrl":"10.1016/j.anaerobe.2024.102920","url":null,"abstract":"<div><div><em>Clostridioides difficile</em> has been recognized as an important nosocomial pathogen that causes diarrheal disease as a consequence of antibiotic exposure and costs the healthcare system billions of dollars every year. <em>C. difficile</em> enters the host gut as dormant spores, germinates into vegetative cells, colonizes the gut, and produces toxins TcdA and/or TcdB, leading to diarrhea and inflammation. Spores are the primary transmission vehicle, while the toxins A and B directly contribute to the disease. Thus, toxin production and sporulation are the key traits that determine the success of <em>C. difficile</em> as a pathogen. Both toxins and spores are produced during the late stationary phase in response to various stimuli. This review provides a comprehensive analysis of the current knowledge on the molecular mechanisms, highlighting the regulatory pathways that interconnect toxin gene expression and sporulation in <em>C. difficile</em>. The roles of carbohydrates, amino acids and other nutrients and signals, in modulating these virulence traits through global regulatory networks are discussed. Understanding the links within the gene regulatory network is crucial for developing effective therapeutic strategies against <em>C. difficile</em> infections, potentially leading to targeted interventions that disrupt the co-regulation of toxin production and sporulation.</div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"91 ","pages":"Article 102920"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142613602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.anaerobe.2024.102925
Helena Rodrigues Oliveira , Thuane Mendes Anacleto , Fernanda Abreu , Alex Enrich-Prast
Introduction
Anaerobic digestion integrates waste treatment, energy generation, and nutrient recycling, producing methane mainly through acetoclastic (AM) and hydrogenotrophic methanogenesis (HM). Methanogenic pathway management can improve biogas productivity and quality. The balance between pathways is influenced by environmental and physicochemical conditions, with conflicting results on the effect of different factors often reported. This systematic review aims to clarify the influence of various parameters on methanogenic pathways in anaerobic digesters.
Methods
Literature search was conducted in the Web of Science and Scopus databases. The effects of different parameters on the predominant methanogenic pathway were evaluated using Kruskal-Wallis tests and Spearman's rank correlation.
Results
Thermophilic temperatures and high free ammonia nitrogen concentrations (>300 mg L−1) increase HM, with a strong combined effect of these variables. Conversely, under moderate temperature and ammonia concentrations, the primary feedstock influences the methanogenic pathway, with algae biomass, pig manure, and food industry wastewater showing the lowest contribution of hydrogenotrophic methanogens. pH effect varied with temperature, with acidic and alkaline pH favoring HM in mesophilic and thermophilic digesters, respectively. Furthermore, higher levels of volatile fatty acids (>2000 mg L−1), carbohydrates (>10 g/L) and lipids (>10 g/L) also appeared to favor HM over AM, while most metals – especially Cr, Se and W – promoted AM.
Conclusion
This study emphasizes the role of various factors in methanogenic pathway selection, highlighting the impact of previously overlooked parameters, such as inorganic elements and organic matter composition. These insights are essential for understanding the methanogenic pathway balance and optimizing biogas processes.
简介：厌氧消化集废物处理、能量生成和营养物质循环为一体，主要通过醋酸破酯（AM）和氢营养产甲烷（HM）产生甲烷。产甲烷途径管理可以提高沼气产量和质量。途径之间的平衡受环境和物理化学条件的影响，不同因素的影响结果往往相互矛盾。本文旨在阐明厌氧消化池中各种参数对产甲烷途径的影响。方法：在Web of Science和Scopus数据库中进行文献检索。采用Kruskal-Wallis检验和Spearman秩相关法评价不同参数对主要产甲烷途径的影响。结果：嗜热温度和高游离氨氮浓度（约300 mg/L）使HM升高，且具有较强的综合效应。相反，在中等温度和氨浓度下，主要原料对产甲烷途径有影响，藻类生物质、猪粪和食品工业废水对氢营养型产甲烷菌的贡献最小。pH值的影响随温度的变化而变化，酸性和碱性pH值分别有利于中温消化器和嗜热消化器中的HM。此外，较高水平的挥发性脂肪酸（2000 mg/L）、碳水化合物（10 g/L）和脂质（10 g/L）似乎也有利于HM而不是AM，而大多数金属——尤其是Cr、Se和W——促进AM。结论：本研究强调了多种因素在产甲烷途径选择中的作用，突出了以前被忽视的参数，如无机元素和有机质组成的影响。这些见解对于理解产甲烷途径平衡和优化沼气过程至关重要。
{"title":"New insights into the factors influencing methanogenic pathways in anaerobic digesters","authors":"Helena Rodrigues Oliveira , Thuane Mendes Anacleto , Fernanda Abreu , Alex Enrich-Prast","doi":"10.1016/j.anaerobe.2024.102925","DOIUrl":"10.1016/j.anaerobe.2024.102925","url":null,"abstract":"<div><h3>Introduction</h3><div>Anaerobic digestion integrates waste treatment, energy generation, and nutrient recycling, producing methane mainly through acetoclastic (AM) and hydrogenotrophic methanogenesis (HM). Methanogenic pathway management can improve biogas productivity and quality. The balance between pathways is influenced by environmental and physicochemical conditions, with conflicting results on the effect of different factors often reported. This systematic review aims to clarify the influence of various parameters on methanogenic pathways in anaerobic digesters.</div></div><div><h3>Methods</h3><div>Literature search was conducted in the Web of Science and Scopus databases. The effects of different parameters on the predominant methanogenic pathway were evaluated using Kruskal-Wallis tests and Spearman's rank correlation.</div></div><div><h3>Results</h3><div>Thermophilic temperatures and high free ammonia nitrogen concentrations (>300 mg L<sup>−1</sup>) increase HM, with a strong combined effect of these variables. Conversely, under moderate temperature and ammonia concentrations, the primary feedstock influences the methanogenic pathway, with algae biomass, pig manure, and food industry wastewater showing the lowest contribution of hydrogenotrophic methanogens. pH effect varied with temperature, with acidic and alkaline pH favoring HM in mesophilic and thermophilic digesters, respectively. Furthermore, higher levels of volatile fatty acids (>2000 mg L<sup>−1</sup>), carbohydrates (>10 g/L) and lipids (>10 g/L) also appeared to favor HM over AM, while most metals – especially Cr, Se and W – promoted AM.</div></div><div><h3>Conclusion</h3><div>This study emphasizes the role of various factors in methanogenic pathway selection, highlighting the impact of previously overlooked parameters, such as inorganic elements and organic matter composition. These insights are essential for understanding the methanogenic pathway balance and optimizing biogas processes.</div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"91 ","pages":"Article 102925"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142765749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.anaerobe.2024.102923
Miyuki Kodera , Kohei Nakamura , S. Yokoyama
Objectives
Equol is a metabolite of isoflavone. Here, we investigated the effect of dietary fiber on equol-producing microbiota.
Methods
Human feces was anaerobically cultured in Gifu Anaerobic Medium (GAM) containing 1 mg/L daidzein supplemented with 1 % (w/v) dietary fiber (pectin, chitin, or resistant starch [RS]). The equol conversion rate, number of equol-producing bacteria, pH, short-chain fatty acids (SCFAs), and microbial composition were measured in fecal cultures.
Results
Equol conversion significantly increased by 2.7-fold in the chitin group compared with the control group. Conversely, the conversion rate decreased to one-tenth in the pectin group and one-third in the RS group. The number of equol-producing bacteria also significantly increased in the chitin group compared with the control group. Whereas pH values and acetate/propionate concentrations decreased in the pectin and RS groups compared with the control group, no significant differences were observed in the chitin group. Microbiota analysis indicated that the relative abundances of Bifidobacterium and Lactobacillus increased, whereas those of Dorea, Lachnoclostridium, and Eggerthella decreased in the pectin and RS groups. In contrast, these abundances remained stable in the chitin group. The relative abundances of Adlercreutzia and Slackia remained unchanged across all groups. In vitro cultures of Eggerthella sp. strain YY7918 and Adlercreutzia equolifaicens JCM14793 demonstrated that equol conversion from daidzein was stimulated by the addition of 0.5–1% (w/v) n-acetylglucosamine, a breakdown product of chitin, but not chitin itself.
Conclusions
Our findings suggest that equol production is stimulated by n-acetylglucosamine, derived from decomposed chitin, in certain equol-producing bacteria without affecting their growth.
{"title":"Chitin promotes equol production via n-acetylglucosamine in human fecal cultures","authors":"Miyuki Kodera , Kohei Nakamura , S. Yokoyama","doi":"10.1016/j.anaerobe.2024.102923","DOIUrl":"10.1016/j.anaerobe.2024.102923","url":null,"abstract":"<div><h3>Objectives</h3><div>Equol is a metabolite of isoflavone. Here, we investigated the effect of dietary fiber on equol-producing microbiota.</div></div><div><h3>Methods</h3><div>Human feces was anaerobically cultured in Gifu Anaerobic Medium (GAM) containing 1 mg/L daidzein supplemented with 1 % (w/v) dietary fiber (pectin, chitin, or resistant starch [RS]). The equol conversion rate, number of equol-producing bacteria, pH, short-chain fatty acids (SCFAs), and microbial composition were measured in fecal cultures.</div></div><div><h3>Results</h3><div>Equol conversion significantly increased by 2.7-fold in the chitin group compared with the control group. Conversely, the conversion rate decreased to one-tenth in the pectin group and one-third in the RS group. The number of equol-producing bacteria also significantly increased in the chitin group compared with the control group. Whereas pH values and acetate/propionate concentrations decreased in the pectin and RS groups compared with the control group, no significant differences were observed in the chitin group. Microbiota analysis indicated that the relative abundances of <em>Bifidobacterium</em> and <em>Lactobacillus</em> increased, whereas those of <em>Dorea</em>, <em>Lachnoclostridium</em>, and <em>Eggerthella</em> decreased in the pectin and RS groups. In contrast, these abundances remained stable in the chitin group. The relative abundances of <em>Adlercreutzia</em> and <em>Slackia</em> remained unchanged across all groups. <em>In vitro</em> cultures of <em>Eggerthella</em> sp. strain YY7918 and <em>Adlercreutzia equolifaicens</em> JCM14793 demonstrated that equol conversion from daidzein was stimulated by the addition of 0.5–1% (w/v) <span><em>n</em></span>-acetylglucosamine, a breakdown product of chitin, but not chitin itself.</div></div><div><h3>Conclusions</h3><div>Our findings suggest that equol production is stimulated by <span><em>n</em></span>-acetylglucosamine, derived from decomposed chitin, in certain equol-producing bacteria without affecting their growth.</div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"91 ","pages":"Article 102923"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142738151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.anaerobe.2025.102940
Liam Wood , Bunmi B. Omorotionmwan , Adam M. Blanchard , Adam Dowle , David Tooth , Tom S. Bailey , Ruth Griffin
Objectives
Clostridium butyricum ferments non-digested dietary fibre in the colon to produce butyric acid. Butyrate is a four-carbon, short-chain fatty acid (SCFA) which has multiple health benefits. Many microbial products of pharmaceutical or industrial interest, such as butyrate, are produced in low quantities due to rate-limiting steps in their metabolic pathway, including low abundance or low activity of one or more enzymes in the pathway. By identifying the former, appropriate enzymes can be over-expressed to increase product yields, however, methods to determine these enzymes are laborious. To improve butyrate production in C. butyricum probiotic strain, CBM588, a novel rapid genome-proteome approach was deployed.
Methods
First, whole genome sequencing was performed and the 8 genes involved in butyrate production identified on the chromosome. Second, the relative abundance of these enzymes was investigated by liquid chromatography-mass spectrometry (LC-MS) analysis of total cytosolic proteins from early stationary phase cultures.
Results
Phosphotransbutyrylase (Ptb), butyrate kinase (Buk) and crotonase (Crt) were found to be the least abundant. Over-expression episomally of the corresponding genes individually or of the ptb-buk bicistron led to significant increases in butyrate titre per density of culture from 10 to 24 h, compared to the wild type.
Conclusions
Our findings pave the way for over-expressing these genes chromosomally to generate a recombinant probiotic with improved butyrate production and potentially enhanced gut health properties.
{"title":"A rapid genome-proteome approach to identify rate-limiting steps in the butyrate production pathway in probiotic Clostridium butyricum, CBM588","authors":"Liam Wood , Bunmi B. Omorotionmwan , Adam M. Blanchard , Adam Dowle , David Tooth , Tom S. Bailey , Ruth Griffin","doi":"10.1016/j.anaerobe.2025.102940","DOIUrl":"10.1016/j.anaerobe.2025.102940","url":null,"abstract":"<div><h3>Objectives</h3><div><em>Clostridium butyricum</em> ferments non-digested dietary fibre in the colon to produce butyric acid. Butyrate is a four-carbon, short-chain fatty acid (SCFA) which has multiple health benefits. Many microbial products of pharmaceutical or industrial interest, such as butyrate, are produced in low quantities due to rate-limiting steps in their metabolic pathway, including low abundance or low activity of one or more enzymes in the pathway. By identifying the former, appropriate enzymes can be over-expressed to increase product yields, however, methods to determine these enzymes are laborious. To improve butyrate production in <em>C. butyricum</em> probiotic strain, CBM588, a novel rapid genome-proteome approach was deployed.</div></div><div><h3>Methods</h3><div>First, whole genome sequencing was performed and the 8 genes involved in butyrate production identified on the chromosome. Second, the relative abundance of these enzymes was investigated by liquid chromatography-mass spectrometry (LC-MS) analysis of total cytosolic proteins from early stationary phase cultures.</div></div><div><h3>Results</h3><div>Phosphotransbutyrylase (Ptb), butyrate kinase (Buk) and crotonase (Crt) were found to be the least abundant. Over-expression episomally of the corresponding genes individually or of the <em>ptb-buk</em> bicistron led to significant increases in butyrate titre per density of culture from 10 to 24 h, compared to the wild type.</div></div><div><h3>Conclusions</h3><div>Our findings pave the way for over-expressing these genes chromosomally to generate a recombinant probiotic with improved butyrate production and potentially enhanced gut health properties.</div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"92 ","pages":"Article 102940"},"PeriodicalIF":2.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143073401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-31DOI: 10.1016/j.anaerobe.2025.102941
Robert Knop, Simon Keweloh, Johanna Pukall, Silvia Dittmann, Daniela Zühlke, Susanne Sievers
Objectives
The microaerophilic conditions in the large intestine and reactive oxygen species (ROS) produced by the immune system represent a challenge for the strictly anaerobic pathogen Clostridioides difficile, which protects itself by a variety of oxidative stress proteins. Four of these are encoded in an operon that has been implicated in the detoxification of H2O2 and O2●-. In this study, proteins of this operon, i. e. a rubrerythrin (Rbr), a superoxide reductase (Sor) and a putative glutamate dehydrogenase (CD630_08280) were investigated for their ROS detoxifying activity in vitro.
Methods
Recombinant proteins were overexpressed in C. difficile and purified anaerobically by affinity chromatography. The H2O2-reductase activity was determined by measuring the NADH consumption after peroxide addition. Superoxide detoxification potential of Sor was detected colorimetrically using a xanthine/xanthine oxidase system with cytochrome c as analytical probe.
Results
Proposed roles of the investigated proteins in the detoxification pathways of ROS could partially be demonstrated. Specifically, Rbr and glutamate dehydrogenase synergistically detoxify H2O2, although with a very low turnover. Furthermore, Sor was shown to scavenge O2●- by superoxide dismutase activity and its activity was compared to superoxide dismutase of Escherichia coli.
Conclusions
The investigated gene locus codes for an oxidative stress operon whose members have the potential to neutralize O2●- and H2O2 to water and thus complements the arsenal of ROS detoxifying mechanisms that are already known in C. difficile. However, full activity with adequate physiological electron transfer partners still needs to be demonstrated.
{"title":"A rubrerythrin locus of Clostridioides difficile encodes enzymes that efficiently detoxify reactive oxygen species","authors":"Robert Knop, Simon Keweloh, Johanna Pukall, Silvia Dittmann, Daniela Zühlke, Susanne Sievers","doi":"10.1016/j.anaerobe.2025.102941","DOIUrl":"10.1016/j.anaerobe.2025.102941","url":null,"abstract":"<div><h3>Objectives</h3><div>The microaerophilic conditions in the large intestine and reactive oxygen species (ROS) produced by the immune system represent a challenge for the strictly anaerobic pathogen <em>Clostridioides difficile</em>, which protects itself by a variety of oxidative stress proteins. Four of these are encoded in an operon that has been implicated in the detoxification of H<sub>2</sub>O<sub>2</sub> and O<sub>2</sub><sup>●-</sup>. In this study, proteins of this operon, i. e. a rubrerythrin (Rbr), a superoxide reductase (Sor) and a putative glutamate dehydrogenase (CD630_08280) were investigated for their ROS detoxifying activity <em>in vitro</em>.</div></div><div><h3>Methods</h3><div>Recombinant proteins were overexpressed in <em>C. difficile</em> and purified anaerobically by affinity chromatography. The H<sub>2</sub>O<sub>2</sub>-reductase activity was determined by measuring the NADH consumption after peroxide addition. Superoxide detoxification potential of Sor was detected colorimetrically using a xanthine/xanthine oxidase system with cytochrome <em>c</em> as analytical probe.</div></div><div><h3>Results</h3><div>Proposed roles of the investigated proteins in the detoxification pathways of ROS could partially be demonstrated. Specifically, Rbr and glutamate dehydrogenase synergistically detoxify H<sub>2</sub>O<sub>2</sub>, although with a very low turnover. Furthermore, Sor was shown to scavenge O<sub>2</sub><sup>●-</sup> by superoxide dismutase activity and its activity was compared to superoxide dismutase of <em>Escherichia coli</em>.</div></div><div><h3>Conclusions</h3><div>The investigated gene locus codes for an oxidative stress operon whose members have the potential to neutralize O<sub>2</sub><sup>●-</sup> and H<sub>2</sub>O<sub>2</sub> to water and thus complements the arsenal of ROS detoxifying mechanisms that are already known in <em>C. difficile</em>. However, full activity with adequate physiological electron transfer partners still needs to be demonstrated.</div></div>","PeriodicalId":8050,"journal":{"name":"Anaerobe","volume":"92 ","pages":"Article 102941"},"PeriodicalIF":2.5,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143078486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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