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Diabetes mellitus represents a significant global health problem. The number of people suffering from this metabolic disease is constantly rising and although the incidence is heterogeneous depending on region, country, economic situation, lifestyle, diet and level of medical care, it is increasing worldwide, especially among youths and children, mainly due to lifestyle and environmental changes. The pathogenesis of the two most common subtypes of diabetes mellitus, type 1 (T1DM) and type 2 (T2DM), is substantially different, so each form is characterized by a different causation, etiology, pathophysiology, presentation, and treatment. Research in recent decades increasingly indicates the potential role of the gut microbiome in the initiation, development, and progression of this disease. Intestinal microbes and their fermentation products have an important impact on host metabolism, immune system, nutrient digestion and absorption, gut barrier integrity and protection against pathogens. This review summarizes the current evidence on the changes in gut microbial populations in both types of diabetes mellitus. Attention is focused on changes in the abundance of specific bacterial groups at different taxonomic levels in humans, and microbiome shift is also assessed in relation to geographic location, age, diet and antidiabetic drug. The causal relationship between gut bacteria and diabetes is still unclear, and future studies applying new methodological approaches to a broader range of microorganisms inhabiting the digestive tract are urgently needed. This would not only provide a better understanding of the role of the gut microbiome in this metabolic disease, but also the use of beneficial bacterial species in the form of probiotics for the treatment of diabetes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2025 Fliegerová, Mahayri, Sechovcová, Mekadim, Mrázek, Jarošíková, Dubský and Fejfarová.)

Diabetes mellitus is a chronic disease affecting glucose metabolism. The pathophysiological reactions underpinning the disease can lead to the development of late diabetes complications. The gut microbiota plays important roles in weight regulation and the maintenance of a healthy digestive system. Obesity, diabetes mellitus, diabetic retinopathy, diabetic nephropathy and diabetic neuropathy are all associated with a microbial imbalance in the gut. Modern technical equipment and advanced diagnostic procedures, including xmolecular methods, are commonly used to detect both quantitative and qualitative changes in the gut microbiota. This review summarises collective knowledge on the role of the gut microbiota in both types of diabetes mellitus and their late complications, with a particular focus on diabetic foot syndrome., (© 2023. Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i.)

Stress increases plasma concentrations of corticosteroids, however, their tissue levels are unclear. Using a repeated social defeat paradigm, we examined the impact of chronic stress on tissue levels of corticosterone (CORT), progesterone (PROG), 11-deoxycorticosterone (11DOC) and 11-dehydrocorticosterone (11DHC) and on gut microbiota, which may reshape the stress response. Male BALB/c mice, liquid chromatography-tandem mass spectrometry and 16S RNA gene sequencing were used to screen steroid levels and fecal microbiome, respectively. Stress induced greater increase of CORT in the brain, liver, and kidney than in the colon and lymphoid organs, whereas 11DHC was the highest in the colon, liver and kidney and much lower in the brain and lymphoid organs. The CORT/11DHC ratio in plasma was similar to the brain but much lower in other organs. Stress also altered tissue levels of PROG and 11DOC and the PROG/11DOC ratio was much higher in lymphoid organs that in plasma and other organs. Stress impacted the β- but not the α-diversity of the gut microbiota and LEfSe analysis revealed several biomarkers associated with stress treatment. Our data indicate that social defeat stress modulates gut microbiota diversity and induces tissue-dependent changes in local levels of corticosteroids, which often do not reflect their systemic levels., (© 2023. The Author(s).)

The present study investigated whether neonatal exposure to the proinflammatory endotoxin lipopolysaccharide (LPS) followed by an antibiotic (ATB)-induced dysbiosis in early adulthood could induce neurodevelopmental disorders-like behavioral changes in adult male rats. Combining these two stressors resulted in decreased weight gain, but no significant behavioral abnormalities were observed. LPS treatment resulted in adult rats' hypoactivity and induced anxiety-like behavior in the social recognition paradigm, but these behavioral changes were not exacerbated by ATB-induced gut dysbiosis. ATB treatment seriously disrupted the gut bacterial community, but dysbiosis did not affect locomotor activity, social recognition, and acoustic reactivity in adult rats. Fecal bacterial community analyses showed no differences between the LPS challenge exposed/unexposed rats, while the effect of ATB administration was decisive regardless of prior LPS exposure. ATB treatment resulted in significantly decreased bacterial diversity, suppression of Clostridiales and Bacteroidales, and increases in Lactobacillales, Enterobacteriales, and Burkholderiales. The persistent effect of LPS on some aspects of behavior suggests a long-term effect of early toxin exposure that was not observed in ATB-treated animals. However, an anti-inflammatory protective effect of ATB cannot be assumed because of the increased abundance of pro-inflammatory, potentially pathogenic bacteria ( Proteus , Suttrella ) and the elimination of the bacterial families Ruminococcaceae and Lachnospiraceae , which are generally considered beneficial for gut health., Competing Interests: The authors declare the following conflict of interests: Tomaš Paleniček declares to have shares in „Psyon s. r.o”., has founded „PSYRES - Psychedelic Research Foundation” and has shares in “Společnost pro podporu neurovědního výzkumu s. r.o”. He reports consulting fees from GH Research and CB21-Pharma outside the submitted work. He is involved in Compass Pathways trials with psilocybin and MAPS clinical trial with MDMA outside the submitted work.TP declare to have shares in „Psyon s. r.o”., has founded „PSYRES - Psychedelic Research Foundation” and has shares in “Společnost pro podporu neurovědního výzkumu s. r.o”. TP reports consulting fees from GH Research and CB21-Pharma outside the submitted work. TP is involved in Compass Pathways trials with psilocybin and MAPS clinical trial with MDMA outside the submitted work., (© 2023 Published by Elsevier Ltd.)

The aim of this study was to compare the diversity and composition of fecal bacteria in goats and cows offered the same diet and to evaluate the influence of animal species on the gut microbiome. A total of 17 female goats (Blond Adamellan) and 16 female cows (Brown Swiss) kept on an organic farm were fed pasture and hay. Bacterial structure in feces was examined by high-throughput sequencing using the V4-V5 region of the 16S rRNA gene. The Alpha diversity measurements of the bacterial community showed no statistical differences in species richness and diversity between the two groups of ruminants. However, the Pielou evenness index revealed a significant difference and showed higher species evenness in cows compared to goats. Beta diversity measurements showed statistical dissimilarities and significant clustering of bacterial composition between goats and cows. Firmicutes were the dominant phylum in both goats and cows, followed by Bacteroidetes, Proteobacteria, and Spirochaetes. Linear discriminant analysis with effect size (LEfSe) showed a total of 36 significantly different taxa between goats and cows. Notably, the relative abundance of Ruminococcaceae UCG-005, Christensenellaceae R-7 group, Ruminococcaceae UCG-010, Ruminococcaceae UCG-009, Ruminococcaceae UCG-013, Ruminococcaceae UCG-014, Ruminococcus 1, Ruminococcaceae UCG-002, Lachnospiraceae NK4A136 group, Treponema 2, Lachnospiraceae AC2044 group, and Bacillus was higher in goats compared to cows. In contrast, the relative abundance of Turicibacter , Solibacillus , Alloprevotella , Prevotellaceae UCG-001, Negativibacillus , Lachnospiraceae UCG-006, and Eubacterium hallii group was higher in cows compared with goats. Our results suggest that diet shapes the bacterial community in feces, but the host species has a significant impact on community structure, as reflected primarily in the relative abundance of certain taxa.

This work investigated the changes of the rumen microbiome of goats switched from a forage to a concentrate diet with special attention to anaerobic fungi (AF). Female goats were fed an alfalfa hay (AH) diet (0% grain; n = 4) for 20 days and were then abruptly shifted to a high-grain (HG) diet (40% corn grain, 60% AH; n = 4) and treated for another 10 days. Rumen content samples were collected from the cannulated animals at the end of each diet period (day 20 and 30). The microbiome structure was studied using high-throughput sequencing for bacteria, archaea (16S rRNA gene) and fungi (ITS2), accompanied by qPCR for each group. To further elucidate unclassified AF, clone library analyses were performed on the ITS1 spacer region. Rumen pH was significantly lower in HG diet fed goats, but did not induce subacute ruminal acidosis. HG diet altered prokaryotic communities, with a significant increase of Bacteroidetes and a decrease of Firmicutes. On the genus level Prevotella 1 was significantly boosted. Methanobrevibacter and Methanosphaera were the most abundant archaea regardless of the diet and HG induced a significant augmentation of unclassified Thermoplasmatales. For anaerobic fungi, HG triggered a considerable rise in Feramyces observed with both ITS markers, while a decline of Tahromyces was detected by ITS2 and decrease of Joblinomyces by ITS1 only. The uncultured BlackRhino group revealed by ITS1 and further elucidated in one sample by LSU analysis, formed a considerable part of the AF community of goats fed both diets. Results strongly indicate that the rumen ecosystem still acts as a source for novel microorganisms and unexplored microbial interactions and that initial rumen microbiota of the host animal considerably influences the reaction pattern upon diet change.

A 1000-cow study across four European countries was undertaken to understand to what extent ruminant microbiomes can be controlled by the host animal and to identify characteristics of the host rumen microbiome axis that determine productivity and methane emissions. A core rumen microbiome, phylogenetically linked and with a preserved hierarchical structure, was identified. A 39-member subset of the core formed hubs in co-occurrence networks linking microbiome structure to host genetics and phenotype (methane emissions, rumen and blood metabolites, and milk production efficiency). These phenotypes can be predicted from the core microbiome using machine learning algorithms. The heritable core microbes, therefore, present primary targets for rumen manipulation toward sustainable and environmentally friendly agriculture.

Background: The rumen microbiota is one of the most complex consortia of anaerobes, involving archaea, bacteria, protozoa, fungi and phages. They are very effective at utilizing plant polysaccharides, especially cellulose and hemicelluloses. The most important hemicellulose decomposers are clustered with the genus Butyrivibrio . As the related species differ in their range of hydrolytic activities and substrate preferences, Butyrivibrio fibrisolvens was selected as one of the most effective isolates and thus suitable for proteomic studies on substrate comparisons in the extracellular fraction. The B. fibrisolvens genome is the biggest in the butyrivibria cluster and is focused on "environmental information processing" and "carbohydrate metabolism"., Methods: The study of the effect of carbon source on B. fibrisolvens 3071 was based on cultures grown on four substrates: xylose, glucose, xylan, xylan with 25% glucose. The enzymatic activities were studied by spectrophotometric and zymogram methods. Proteomic study was based on genomics, 2D electrophoresis and nLC/MS (Bruker Daltonics) analysis., Results: Extracellular β-endoxylanase as well as xylan β-xylosidase activities were induced with xylan. The presence of the xylan polymer induced hemicellulolytic enzymes and increased the protein fraction in the interval from 40 to 80 kDa. 2D electrophoresis with nLC/MS analysis of extracellular B. fibrisolvens 3071 proteins found 14 diverse proteins with significantly different expression on the tested substrates., Conclusion: The comparison of four carbon sources resulted in the main significant changes in B. fibrisolvens proteome occurring outside the fibrolytic cluster of proteins. The affected proteins mainly belonged to the glycolysis and protein synthesis cluster., Competing Interests: Competing interestsThe authors declare that they have no competing interests.

Gram-stain-positive, catalase and oxidase-negative and short rod-shaped bacterium C10 with occasional branching was isolated under strictly anaerobic conditions from the rumen fluid of a red deer (Cervus elaphus) in the course of study attempting to uncover new xylanolytic and cellulolytic rumen bacteria inhabiting the digestive tract of wild ruminants in the Czech Republic. The anaerobic M10 medium containing bovine rumen fluid and carboxymethylcellulose as a defined source of organic carbon was used in the process of bacterial isolation. The 16S rRNA gene similarity revealed recently characterized new species Actinomyces succiniciruminis Am4 T (GenBank accession number of the gene retrieved from the complete genome: LK995506) and Actinomyces glycerinitolerans G10 T (GenBank accession number from the complete genome: NZFQTT01000017) as the closest relatives (99.7 and 99.6% gene pairwise identity, respectively), followed by the Actinomyces ruminicola DSM 27982 T (97.2%, in all compared fragment of 41468 pb). Due to the taxonomic affinity of the examined strain to both species A. succiniciruminis and A. glycerinitolerans, its taxonomic status towards these species was evaluated using variable regions of rpsA (length of 519 bp) and rplB (597 bp) gene sequences amplified based on specific primers designed so as to be applicable in differentiation, classification, and phylogeny of Actinomyces species/strains. Comparative analyses using rpsA and rplB showed 98.5 and 97.9% similarities of C10 to A. succiniciruminis, respectively, and 97.5 and 97.6% similarities to A. glycerinitolerans, respectively. Thus, gene identities revealed that the evaluated isolate C10 (=DSM 100236 = LMG 28777) is a little more related to the species A. succiniciruminis isolated from the rumen of a Holstein-Friesian cow than A. glycerinitolerans. Phylogenetic analyses confirmed affinity of strain C10 to both recently characterized species. Unfortunately, they did not allow the bacterial strain to be classified into a particular species. Phenotypic characterization suggested similar conclusions. This brief contribution is aimed at classification and detailed phenotypic characterization of bacterial strain C10 isolated from the rumen of a wild red deer exhibiting, from the point of view of Actinomyces species, noteworthy cellulolytic and xylanolytic activities.

Bark beetles reproduce and overwinter under the bark of trees, and are associated with bacteria that may influence the fitness of their hosts. As regard the aim of this study was to test the metabolic potential of bacterial strains, isolated from the bark beetle species Cryphalus piceae, Ips typographus and Pityophthorus pityophthorus and collected in the Czech Republic from fir, spruce and pine trees, respectively, to degrade plant cell compounds. The bacterial strains were identified as belonging to the genera Curtobacterium, Erwinia, Pantoea, Pseudomonas, Rahnella, Staphylococcus, and Yersinia. Several activities related to the degradation of lignocellulosic materials, such as cellulose, xylan and starch, were found. Moreover, the genomes of three of these strains were sequenced and analyzed, and the presence of the enzymatic machinery required for biomass hydrolysis was discovered. This finding supports the idea that bacteria aid in the provision of nutrients to the beetle from the hydrolysis of tree compounds, results that are relevant for studying the ecological implication of bacterial strains in the bark beetle life cycle. In addition, the activities found in association with the bacterial strains could be useful in biotechnological processes, such as the production of biofuels from biomass, colorant degradation, in the textile industry and for wastewater treatments. Furthermore, the gene sequences of the lignocellulolytic enzymes found within the genomes serve as a basis for future studies regarding the potential application of these bacteria, and their metabolic machinery, in processes such as biomass hydrolysis and bioremediation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A slightly irregular, short rod-shaped bacterial strain, MOZIV/2T, showing activity of fructose 6-phosphate phosphoketolase was isolated from the oral cavity of a home-bred guinea-pig. Based on comparative 16S rRNA gene sequence analyses, its closest relatives were Alloscardovia omnicolens DSM 21503T and Alloscardovia criceti DSM 17774T with 96.0 and 95.6 % pairwise similarities, respectively. Completeness of the compared sequences was 97.3 and 96.9 %, respectively. Growth was found only under anaerobic conditions. Activities of α- and β-gluco(galacto)sidases were detected in strain MOZIV/2T, which is characteristic for almost all members of the family Bifidobacteriaceae. Sequencing of other molecular markers (fusA, gyrB and xfp) revealed low gene sequence similarities to A. omnicolens DSM 21503T ranging from 72.7 to 87.5 %. Strain MOZIV/2T differed from other species within the genus Alloscardovia by the presence of C18 : 1ω9t. In addition, much higher proportions of C8 : 0, C11 : 0, C12 : 0, C14 : 1, C16 : 1 and C17 : 0 fatty acids were found in cells of strain MOZIV/2T. The peptidoglycan structure was of type A4α [l-Lys(l-Orn)-d-Asp], which is consistent with its classification within the genus Alloscardovia. The DNA G+C content (45.8 mol%) was lower than those found in other alloscardovia. Phylogenetic studies and evaluation of phenotypic characteristics including the results of biochemical, physiological and chemotaxonomic analyses confirmed the novel species status for strain MOZIV/2T, for which the name Alloscardovia venturai sp. nov. is proposed. The type strain is MOZIV/2T (=DSM 100237T=CCM 8604T=LMG 28781T).

Three strains of a butyrate-producing bacterium were isolated from the rumen contents of grazing sheep and cows. The strains were anaerobic, with Gram-positive cell walls, straight-to-slightly-curved, rod-shaped, non-spore-forming and single flagellate. C 14 : 1 , C 14 : 0 , C 16 : 0 and C 16 : 1 were the predominant fatty acids. The cell-wall peptidoglycan type was A1 γ . The DNA G+C content varied from 41.4 to 42.2 mol%. 16S rRNA gene sequence similarities between the isolates and Eubacterium rectale , Roseburia hominis and Roseburia intestinalis were found to be 96, 95 and 95 %, respectively. The phylogenetic tree showed that the strains constituted a different taxon, separate from other taxa with validly published names and forming a cluster with strains of Eubacterium rectale. On the basis of phenotypic, chemotaxonomic and phylogenetic results (16S RNA, dnaK , groEL , atpA genes), the isolates are considered to represent a novel species of a new genus of the family Lachnospiraceae , for which the name Agathobacter ruminis gen. nov., sp. nov. is proposed (type strain JK623 T  = DSM 29029 T  = LMG 28559 T ). We also propose the transfer of Eubacterium rectale to the new genus as Agathobacter rectalis gen. nov., comb nov. This new genus represents saccharoclastic, chemo-organotrophic and obligatory anaerobic, non-spore-forming rods with Gram-positive membrane. The main fermentation products on peptone yeast glucose (PYG) medium were butyrate, acetate, hydrogen and lactate. The type species of the genus is Agathobacter rectalis gen. nov., comb nov. (Prévot, 1938) with type strain ATCC 33656 T ( = JCM 17463 T ).