Feather bacterial load affects key avian life-history traits such as plumage condition, innate immunity, and reproductive success. Investigating the interplay between life-history traits and feather microbial load is critical for understanding mechanisms of host-microbiome interactions. We hypothesize that spatiotemporal variation associated with migration and molting, body size affecting colonizable body surface area, and preening intensity could shape feather bacterial load. Integrating 16S rDNA-qPCR and flow cytometry, we examined total and viable bacterial loads in the feathers of 316 individuals of 24 Palearctic passerine species. We found that viable bacterial load in feathers was lower in larger species and higher in residents compared to migrants. In contrast, total bacterial load was not explained by any of the life-history traits but varied considerably among species, sampling sites, and years. By pinpointing main drivers of bacterial loads on avian body surfaces, we identify key mechanisms shaping host-microbiome interactions and open alternative research directions.

• Klíčová slova
• Evolutionary biology, Microbiology, Ornithology,
• Publikační typ
• časopisecké články MeSH

The decomposition of wood and detritus is challenging to most macroscopic organisms due to the recalcitrant nature of lignocellulose. Moreover, woody plants often protect themselves by synthesizing toxic or nocent compounds which infuse their tissues. Termites are essential wood decomposers in warmer terrestrial ecosystems and, as such, they have to cope with high concentrations of plant toxins in wood. In this paper, we evaluated the influence of wood age on the gut microbial (bacterial and fungal) communities associated with the termites Reticulitermes flavipes (Rhinotermitidae) (Kollar, 1837) and Microcerotermes biroi (Termitidae) (Desneux, 1905). We confirmed that the secondary metabolite concentration decreased with wood age. We identified a core microbial consortium maintained in the gut of R. flavipes and M. biroi and found that its diversity and composition were not altered by the wood age. Therefore, the concentration of secondary metabolites had no effect on the termite gut microbiome. We also found that both termite feeding activities and wood age affect the wood microbiome. Whether the increasing relative abundance of microbes with termite activities is beneficial to the termites is unknown and remains to be investigated. IMPORTANCE Termites can feed on wood thanks to their association with their gut microbes. However, the current understanding of termites as holobiont is limited. To our knowledge, no studies comprehensively reveal the influence of wood age on the termite-associated microbial assemblage. The wood of many tree species contains high concentrations of plant toxins that can vary with their age and may influence microbes. Here, we studied the impact of Norway spruce wood of varying ages and terpene concentrations on the microbial communities associated with the termites Reticulitermes flavipes (Rhinotermitidae) and Microcerotermes biroi (Termitidae). We performed a bacterial 16S rRNA and fungal ITS2 metabarcoding study to reveal the microbial communities associated with R. flavipes and M. biroi and their impact on shaping the wood microbiome. We noted that a stable core microbiome in the termites was unaltered by the feeding substrate, while termite activities influenced the wood microbiome, suggesting that plant secondary metabolites have negligible effects on the termite gut microbiome. Hence, our study shed new insights into the termite-associated microbial assemblage under the influence of varying amounts of terpene content in wood and provides a groundwork for future investigations for developing symbiont-mediated termite control measures.

• Klíčová slova
• Microcerotermes biroi, Reticulitermes flavipes, bacteria, core-microbiome, ectosymbionts, endosymbionts, fungi, plant defenses, terpenoids, wood-feeding termites,
• MeSH
• Bacteria genetika   MeSH
• dřevo * metabolismus   MeSH
• ekosystém MeSH
• Isoptera * mikrobiologie   MeSH
• RNA ribozomální 16S genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• RNA ribozomální 16S MeSH

BACKGROUND: Termites primarily feed on lignocellulose or soil in association with specific gut microbes. The functioning of the termite gut microbiota is partly understood in a handful of wood-feeding pest species but remains largely unknown in other taxa. We intend to fill this gap and provide a global understanding of the functional evolution of termite gut microbiota. RESULTS: We sequenced the gut metagenomes of 145 samples representative of the termite diversity. We show that the prokaryotic fraction of the gut microbiota of all termites possesses similar genes for carbohydrate and nitrogen metabolisms, in proportions varying with termite phylogenetic position and diet. The presence of a conserved set of gut prokaryotic genes implies that essential nutritional functions were present in the ancestor of modern termites. Furthermore, the abundance of these genes largely correlated with the host phylogeny. Finally, we found that the adaptation to a diet of soil by some termite lineages was accompanied by a change in the stoichiometry of genes involved in important nutritional functions rather than by the acquisition of new genes and pathways. CONCLUSIONS: Our results reveal that the composition and function of termite gut prokaryotic communities have been remarkably conserved since termites first appeared ~ 150 million years ago. Therefore, the "world's smallest bioreactor" has been operating as a multipartite symbiosis composed of termites, archaea, bacteria, and cellulolytic flagellates since its inception. Video Abstract.

• Klíčová slova
• Endosymbionts, Isoptera, Metagenomics, Vertical inheritance,
• MeSH
• fylogeneze MeSH
• Isoptera * MeSH
• metagenom MeSH
• půda MeSH
• střevní mikroflóra * genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• audiovizuální média MeSH
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• půda MeSH

Actinobacteria are important cave inhabitants, but knowledge of how anthropization and anthropization-related visual marks affect this community on cave walls is lacking. We compared Actinobacteria communities among four French limestone caves (Mouflon, Reille, Rouffignac, and Lascaux) ranging from pristine to anthropized, and within Lascaux Cave between marked (wall visual marks) and unmarked areas in different rooms (Sas-1, Passage, Apse, and Diaclase). In addition to the 16S rRNA gene marker, 441 bp fragments of the hsp65 gene were used and an hsp65-related taxonomic database was constructed for the identification of Actinobacteria to the species level by Illumina-MiSeq analysis. The hsp65 marker revealed higher resolution for species and higher richness (99% operational taxonomic units cutoff) versus the 16S rRNA gene; however, more taxa were identified at higher taxonomic ranks. Actinobacteria communities varied between Mouflon and Reille caves (both pristine), and Rouffignac and Lascaux (both anthropized). Rouffignac displayed high diversity of Nocardia, suggesting human inputs, and Lascaux exhibited high Mycobacterium relative abundance, whereas Gaiellales were typical in pristine caves and the Diaclase (least affected area of Lascaux Cave). Within Lascaux, Pseudonocardiaceae dominated on unmarked walls and Streptomycetaceae (especially Streptomyces mirabilis) on marked walls, indicating a possible role in mark formation. A new taxonomic database was developed. Although not all Actinobacteria species were represented, the use of the hsp65 marker enabled species-level variations of the Actinobacteria community to be documented based on the extent of anthropogenic pressure. This approach proved effective when comparing different limestone caves or specific conditions within one cave.

• Klíčová slova
• 16S rRNA gene sequencing, Actinobacteria, Paleolithic cave, cave anthropization, hsp65 sequencing, metabarcoding,
• MeSH
• Actinobacteria * genetika   MeSH
• Bacteria MeSH
• fylogeneze MeSH
• jeskyně * mikrobiologie   MeSH
• lidé MeSH
• RNA ribozomální 16S genetika   MeSH
• uhličitan vápenatý MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• RNA ribozomální 16S MeSH
• uhličitan vápenatý MeSH

Butyrate is formed in the gut during bacterial fermentation of dietary fiber and is attributed numerous beneficial effects on the host metabolism. We aimed to develop a method for the assessment of functional capacity of gut microbiota butyrate synthesis based on the qPCR quantification of bacterial gene coding butyryl-CoA:acetate CoA-transferase, the key enzyme of butyrate synthesis. In silico, we identified bacteria possessing but gene among human gut microbiota by searching but coding sequences in available databases. We designed and validated six sets of degenerate primers covering all selected bacteria, based on their phylogenetic nearness and sequence similarity, and developed a method for gene abundance normalization in human fecal DNA. We determined but gene abundance in fecal DNA of subjects with opposing dietary patterns and metabolic phenotypes-lean vegans (VG) and healthy obese omnivores (OB) with known fecal microbiota and metabolome composition. We found higher but gene copy number in VG compared with OB, in line with higher fecal butyrate content in VG group. We further found a positive correlation between the relative abundance of target bacterial genera identified by next-generation sequencing and groups of but gene-containing bacteria determined by specific primers. In conclusion, this approach represents a simple and feasible tool for estimation of microbial functional capacity.

• Klíčová slova
• butyrate, functional capacity, gut microbiota,
• MeSH
• bakteriální geny * MeSH
• butyráty metabolismus   MeSH
• DNA bakterií genetika   MeSH
• dospělí MeSH
• feces mikrobiologie   MeSH
• fenotyp MeSH
• fylogeneze MeSH
• genová dávka MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• neparametrická statistika MeSH
• obezita mikrobiologie   MeSH
• polymerázová řetězová reakce * MeSH
• reprodukovatelnost výsledků MeSH
• střevní mikroflóra genetika   MeSH
• vegani MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• butyráty MeSH
• DNA bakterií MeSH

The bacterial genus Sodalis is represented by insect endosymbionts as well as free-living species. While the former have been studied frequently, the distribution of the latter is not yet clear. Here, we present a description of a free-living strain, Sodalis ligni sp. nov., originating from decomposing deadwood. The favored occurrence of S. ligni in deadwood is confirmed by both 16S rRNA gene distribution and metagenome data. Pangenome analysis of available Sodalis genomes shows at least three groups within the Sodalis genus: deadwood-associated strains, tsetse fly endosymbionts and endosymbionts of other insects. This differentiation is consistent in terms of the gene frequency level, genome similarity and carbohydrate-active enzyme composition of the genomes. Deadwood-associated strains contain genes for active decomposition of biopolymers of plant and fungal origin and can utilize more diverse carbon sources than their symbiotic relatives. Deadwood-associated strains, but not other Sodalis strains, have the genetic potential to fix N2, and the corresponding genes are expressed in deadwood. Nitrogenase genes are located within the genomes of Sodalis, including S. ligni, at multiple loci represented by more gene variants. We show decomposing wood to be a previously undescribed habitat of the genus Sodalis that appears to show striking ecological divergence.

• Klíčová slova
• Sodalis, deadwood, free-living, insect symbionts, nitrogen fixation, non-symbiotic,
• Publikační typ
• časopisecké články MeSH

The estimation of oral microbiome (OM) taxonomic composition in periodontally healthy individuals can often be biased because the clinically periodontally healthy subjects for evaluation can already experience dysbiosis. Usually, they are included just based on the absence of clinical signs of periodontitis. Additionally, the age of subjects is used to be higher to correspond well with tested groups of patients with chronic periodontitis, a disorder typically associated with aging. However, the dysbiosis of the OM precedes the clinical signs of the disease by many months or even years. The absence of periodontal pockets thus does not necessarily mean also good periodontal health and the obtained image of "healthy OM" can be distorted.To overcome this bias, we taxonomically characterized the OM in almost a hundred young students of dentistry with precise oral hygiene and no signs of periodontal disease. We compared the results with the OM composition of older periodontally healthy individuals and also a group of patients with severe periodontitis (aggressive periodontitis according to former classification system). The clustering analysis revealed not only two compact clearly separated clusters corresponding to each state of health, but also a group of samples forming an overlap between both well-pronounced states. Additionally, in the cluster of periodontally healthy samples, few outliers with atypical OM and two major stomatotypes could be distinguished, differing in the prevalence and relative abundance of two main bacterial genera: Streptococcus and Veillonella. We hypothesize that the two stomatotypes could represent the microbial succession from periodontal health to starting dysbiosis. The old and young periodontally healthy subjects do not cluster separately but a trend of the OM in older subjects to periodontitis is visible. Several bacterial genera were identified to be typically more abundant in older periodontally healthy subjects.

• Klíčová slova
• aging, core microbiome, oral microbiome, periodontal health, periodontitis, stomatotype, taxonomic composition,
• MeSH
• agresivní parodontitida * MeSH
• chronická parodontitida * MeSH
• dysbióza MeSH
• lidé MeSH
• mikrobiota * MeSH
• parodontální chobot MeSH
• senioři MeSH
• Check Tag
• lidé MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The dysbiosis of oral microbiome (OM) precedes the clinical signs of periodontal disease. Its simple measure thus could indicate individuals at risk of periodontitis development; however, such a tool is still missing. Up to now, numerous microbial taxa were associated with periodontal health or periodontitis. The outputs of most studies could, nevertheless, be slightly biased from following two reasons: First, the healthy group is often characterized only by the absence of the disease, but the individuals could already suffer from dysbiosis without any visible signs. Second, the healthy/diseased OM characteristics are frequently determined based on average data obtained for whole groups of periodontally healthy persons versus patients. Especially in smaller sets of tested individuals the typical individual variability can thus complicate the unambiguous assignment of oral taxa to respective state of health. In this work the taxonomic composition of OM was evaluated for 20 periodontally healthy individuals and 15 patients with chronic periodontitis. The narrowed selection set of the most diseased patients (confirmed by clinical parameters) and the most distant group of healthy individuals with the lowest probability of dysbiosis was determined by clustering analysis and used for identification of marker taxa. Based on their representation in each individual oral cavity we proposed the numeric index of periodontal health called R/G value. Its diagnostic potential was further confirmed using independent set of 20 periodontally healthy individuals and 20 patients with periodontitis with 95 percent of samples assigned correctly. We also assessed the individual temporal OM dynamics in periodontal health and we compared it to periodontitis. We revealed that the taxonomic composition of the system changes dynamically but generally it ranges within values typical for periodontal health or transient state, but far from values typical for periodontitis. R/G value tool, formulated from individually evaluated data, allowed us to arrange individual OMs into a continuous series, instead of two distinct groups, thus mimicking the gradual transformation of a virtual person from periodontal health to disease. The application of R/G value index thus represents a very promising diagnostic tool for early prediction of persons at risk of developing periodontal disease.

• Klíčová slova
• core microbiome, diagnosis, oral microbiome, periodontal health, periodontitis, taxonomic composition, temporal dynamics,
• MeSH
• chronická parodontitida * MeSH
• dysbióza MeSH
• lidé MeSH
• mikrobiota * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Revealing the relationship between taxonomy and function in microbiomes is critical to discover their contribution to ecosystem functioning. However, while the relationship between taxonomic and functional diversity in bacteria and fungi is known, this is not the case for archaea. Here, we used a meta-analysis of 417 completely annotated extant and taxonomically unique archaeal genomes to predict the extent of microbiome functionality on Earth contained within archaeal genomes using accumulation curves of all known level 3 functions of KEGG Orthology. We found that intergenome redundancy as functions present in multiple genomes was inversely related to intragenome redundancy as multiple copies of a gene in one genome, implying the tradeoff between additional copies of functionally important genes or a higher number of different genes. A logarithmic model described the relationship between functional diversity and species richness better than both the unsaturated and the saturated model, which suggests a limited total number of archaeal functions in contrast to the sheer unlimited potential of bacteria and fungi. Using the global archaeal species richness estimate of 13,159, the logarithmic model predicted 4164.1 ± 2.9 KEGG level 3 functions. The non-parametric bootstrap estimate yielded a lower bound of 2994 ± 57 KEGG level 3 functions. Our approach not only highlighted similarities in functional redundancy but also the difference in functional potential of archaea compared to other domains of life.

• Klíčová slova
• archaea, functional diversity, microbiome functionality,
• Publikační typ
• časopisecké články MeSH

Sequencing 16S rRNA gene amplicons is the gold standard to uncover the composition of prokaryotic communities. The presence of multiple copies of this gene makes the community abundance data distorted and gene copy normalization (GCN) necessary for correction. Even though GCN of 16S data provided a picture closer to the metagenome before, it should also be compared with communities of known composition due to the fact that library preparation is prone to methodological biases. Here, we process 16S rRNA gene amplicon data from eleven simple mock communities with DADA2 and estimate the impact of GCN. In all cases, the mock community composition derived from the 16S sequencing differs from those expected, and GCN fails to improve the classification for most of the analysed communities. Our approach provides empirical evidence that GCN does not improve the 16S target sequencing analyses in real scenarios. We therefore question the use of GCN for metataxonomic surveys until a more comprehensive catalogue of copy numbers becomes available.

• Klíčová slova
• 16S rRNA, Gene, Metataxonomic surveys,
• MeSH
• genová dávka MeSH
• genová knihovna MeSH
• metagenom genetika   MeSH
• metagenomika normy   MeSH
• mikrobiota genetika   MeSH
• RNA ribozomální 16S genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• RNA ribozomální 16S MeSH