Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society for Microbiology  

ABSTRACT

Spiroplasma phoeniceum is a plant pathogen and a mesophilic microaerophile. Here, we report the metagenome-assembled genome (MAG) sequence of S. phoeniceum binned from hindgut contents of the wild-type male Locusta migratoria , a grasshopper species. The MAG sequence comprises 1,059,205 bp in 91 contigs with a 26.3% of GC content.

DOI： 10.1128/mra.00353-24

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To quantify the biases introduced during human gut microbiome studies, analyzing an artificial mock community as the reference microbiome is indispensable. However, there are still limited resources for a mock community which well represents the human gut microbiome. Here, we constructed a novel mock community comprising the type strains of 18 major bacterial species in the human gut and assessed the influence of experimental and bioinformatics procedures on the 16S rRNA gene and shotgun metagenomic sequencing. We found that DNA extraction methods greatly affected the DNA yields and taxonomic composition of sequenced reads, and that some of the commonly used primers for 16S rRNA genes were prone to underestimate the abundance of some gut commensal taxa such as Erysipelotrichia, Verrucomicrobiota and Methanobacteriota. Binning of the assembled contigs of shotgun metagenomic sequences by MetaBAT2 produced phylogenetically consistent, less-contaminated bins with varied completeness. The ensemble approach of multiple binning tools by MetaWRAP can improve completeness but sometimes increases the contamination rate. Our benchmark study provides an important foundation for the interpretation of human gut microbiome data by providing means for standardization among gut microbiome data obtained with different methodologies and will facilitate further development of analytical methods.

DOI： 10.1093/dnares/dsad010

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Commensal microbes in animals have a profound impact on tissue homeostasis, stress resistance, and ageing. We previously showed in Drosophila melanogaster that Acetobacter persici is a member of the gut microbiota that promotes ageing and shortens fly lifespan. However, the molecular mechanism by which this specific bacterial species changes lifespan and physiology remains unclear. The difficulty in studying longevity using gnotobiotic flies is the high risk of contamination during ageing. To overcome this technical challenge, we used a bacteria-conditioned diet enriched with bacterial products and cell wall components. Here, we demonstrate that an A. persici-conditioned diet shortens lifespan and increases intestinal stem cell (ISC) proliferation. Feeding adult flies a diet conditioned with A. persici, but not with Lactiplantibacillus plantarum, can decrease lifespan but increase resistance to paraquat or oral infection of Pseudomonas entomophila, indicating that the bacterium alters the trade-off between lifespan and host defence. A transcriptomic analysis using fly intestine revealed that A. persici preferably induces antimicrobial peptides (AMPs), while L. plantarum upregulates amidase peptidoglycan recognition proteins (PGRPs). The specific induction of these Imd target genes by peptidoglycans from two bacterial species is due to the stimulation of the receptor PGRP-LC in the anterior midgut for AMPs or PGRP-LE from the posterior midgut for amidase PGRPs. Heat-killed A. persici also shortens lifespan and increases ISC proliferation via PGRP-LC, but it is not sufficient to alter the stress resistance. Our study emphasizes the significance of peptidoglycan specificity in determining the gut bacterial impact on healthspan. It also unveils the postbiotic effect of specific gut bacterial species, which turns flies into a "live fast, die young" lifestyle.

DOI： 10.1371/journal.pgen.1010709

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Two strictly anaerobic, Gram-stain-positive, non-motile bacteria (strains OPF53T and TOC12T) were isolated from mouse intestines. Strains OPF53T and TOC12T grew at pH 5.5-9.0 and 5.0-9.0, respectively, and at temperatures of 30-45 °C. The cell morphologies of these strains were short rods and rods, respectively, and the cells possessed intracellular granules. The major cellular fatty acids of OPF53T were C18  :  1 cis 9 and C18  :  1 cis 9 dimethyl acetal, whereas those of TOC12T were C18  :  0 and C18  :  1 cis 9. In OPF53T, the main end-products of modified peptone-yeast extract-glucose (PYG) fermentation were lactate, formate and butyrate, whereas, in addition to these acids, TOC12T also produced hydrogen. The genomes of OPF53T and TOC12T were respectively 2.2 and 2.0 Mbp in size with a DNA G+C contents of 69.1 and 58.7 %. The 16S rRNA gene sequences of OPF53T and TOC12T showed the highest similarity to members of the family Atopobiaceae, namely, Olsenella phocaeensis Marseille-P2936T (94.3 %) and Olsenella umbonata KCTC 15140T (93.2 %), respectively. Phylogenetic analyses revealed that both isolates formed distinct lineages from other genera of the family Atopobiaceae. In addition, the two strains were characterized by relatively low 16S rRNA gene sequence similarity (93.4 %) and can be distinguished by their distinctive traits (including cell shape, DNA G+C content, and major fatty acids profiles). On the basis of their polyphasic taxonomic properties, these isolates represent two noel species of two novel genera within the family Atopobiaceae, for which the names Granulimonas faecalis gen. nov., sp. nov. (OPF53T=JCM 35015T=KCTC 25474T) and Leptogranulimonas caecicola gen. nov., sp. nov. (TOC12T=JCM 35017T=KCTC 25472T) are proposed.

DOI： 10.1099/ijsem.0.005596

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Clostridioides difficile causes nosocomial antibiotic-associated diarrhea on a global scale. Susceptibility to C. difficile infection (CDI) is influenced by the composition and metabolism of gut microbiota, which in turn are affected by diet. However, the mechanism underlying the interplay between diet and gut microbiota that modulates susceptibility to CDI remains unclear. Here, we show that a soy protein diet increases the mortality of antibiotic-treated, C. difficile-infected mice while also enhancing the intestinal levels of amino acids (aas) and relative abundance of Lactobacillus genus. Indeed, Ligilactobacillus murinus-mediated fermentation of soy protein results in the generation of aas, thereby promoting C. difficile growth, and the process involves the anchored cell wall proteinase PrtP. Thus, mutual interaction between dietary protein and the gut microbiota is a critical factor affecting host susceptibility to CDI, suggesting that dietary protein sources can be an important determinant in controlling the disease.

DOI： 10.1016/j.celrep.2022.111332

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Background

Cryoconite granules are mineral–microbial aggregates found on glacier surfaces worldwide and are hotspots of biogeochemical reactions in glacier ecosystems. However, despite their importance within glacier ecosystems, the geographical diversity of taxonomic assemblages and metabolic potential of cryoconite communities around the globe remain unclear. In particular, the genomic content of cryoconite communities on Asia’s high mountain glaciers, which represent a substantial portion of Earth’s ice masses, has rarely been reported. Therefore, in this study, to elucidate the taxonomic and ecological diversities of cryoconite bacterial consortia on a global scale, we conducted shotgun metagenomic sequencing of cryoconite acquired from a range of geographical areas comprising Polar (Arctic and Antarctic) and Asian alpine regions.

Results

Our metagenomic data indicate that compositions of both bacterial taxa and functional genes are particularly distinctive for Asian cryoconite. Read abundance of the genes responsible for denitrification was significantly more abundant in Asian cryoconite than the Polar cryoconite, implying that denitrification is more enhanced in Asian glaciers. The taxonomic composition of Cyanobacteria, the key primary producers in cryoconite communities, also differs between the Polar and Asian samples. Analyses on the metagenome-assembled genomes and fluorescence emission spectra reveal that Asian cryoconite is dominated by multiple cyanobacterial lineages possessing phycoerythrin, a green light-harvesting component for photosynthesis. In contrast, Polar cryoconite is dominated by a single cyanobacterial species Phormidesmis priestleyi that does not possess phycoerythrin. These findings suggest that the assemblage of cryoconite bacterial communities respond to regional- or glacier-specific physicochemical conditions, such as the availability of nutrients (e.g., nitrate and dissolved organic carbon) and light (i.e., incident shortwave radiation).

Conclusions

Our genome-resolved metagenomics provides the first characterization of the taxonomic and metabolic diversities of cryoconite from contrasting geographical areas, highlighted by the distinct light-harvesting approaches of Cyanobacteria and nitrogen utilization between Polar and Asian cryoconite, and implies the existence of environmental controls on the assemblage of cryoconite communities. These findings deepen our understanding of the biodiversity and biogeochemical cycles of glacier ecosystems, which are susceptible to ongoing climate change and glacier decline, on a global scale.

DOI： 10.1186/s40168-022-01238-7

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Other Link： https://link.springer.com/article/10.1186/s40168-022-01238-7/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Microbiology Society  

Two obligately anaerobic, Gram-stain-positive, rod-shaped bacteria were isolated from faecal samples of healthy humans in Japan. 16S rRNA gene sequence analysis indicated that these two strains (8CFCBH1^T and 9CBH6) belonged to the genus Adlercreutzia, which is known as an equol-producing bacterium. The closest neighbours of strain 8CFCBH1^T were Adlercreutzia equolifaciens subsp. equolifaciens DSM 19450^T (98.6%), Adlercreutzia equolifaciens subsp. celatus do03^T (98.4%), Adlercreutzia muris WCA-131-CoC-2^T (96.6%), Parvibacter caecicola NR06^T (96.4%), Adlercreutzia caecimuris B7^T (95.3%) and Adlercreutzia mucosicola Mt1B8^T (95.3%). The closest relatives to strain 9CBH6 were A. equolifaciens subsp. equolifaciens DSM 19450^T (99.8%), A. equolifaciens subsp. celatus do03^T (99.6%) and A. muris WCA-131-CoC-2^T (96.8%). Strain 8CFCBH1^T showed 22.3–53.5% digital DNA–DNA hybridization (dDDH) values with its related species. In addition, the average nucleotide identity (ANI) values between strain 8CFCBH1^T and its related species ranged from 75.4 to 93.3%. On the other hand, strain 9CBH6 was considered as A. equolifaciens based on the dDDH and ANI values (>70% dDDH and >95–96% ANI). Strain 9CBH6 showed daidzein-converting activity, as expected from the result of genome analysis. The genome of strain 8CFCBH1^T lacked four genes involved in equol production. Growing cells of strain 8CFCBH1^T were not capable of converting daidzein. Based on the collected data, strain 8CFCBH1^T represents a novel species in the genus Adlercreutzia, for which the name Adlercreutzia hattorii sp. nov. is proposed. The type strain of A. hattorii is 8CFCBH1^T (=JCM 34083^T=DSM 112284^T).

DOI： 10.1099/ijsem.0.005121

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

An obligately anaerobic, Gram-stain-negative, rod-shaped bacterium, designated strain 2CBH44T , was isolated from the fecal sample of a healthy Japanese man. This strain was initially assigned as a novel species of the genus Coprobacter based on the 16S rRNA gene sequence similarities compared with other Coprobacter species. The 16S rRNA gene sequence analysis revealed strain 2CBH44T had relatively low 16S rRNA gene sequence similarity (97.5%) to Coprobacter secundus 177T . However, strain 2CBH44T showed 96.9% average nucleotide identity value with C. secundus 177T , indicating that strain 2CBH44T and C. secundus 177T belong to the same species. On the other hand, the digital DNA-DNA hybridization value between strain 2CBH44T and C. secundus 177T was 73.5%, indicating that strain 2CBH44T is a subspecies of C. secundus. Another anaerobic, Gram-stain-variable, rod-shaped bacterium, designated strain 12CBH8T , was also isolated from human feces. Strain 12CBH8T had significantly low 16S rRNA gene sequence similarities (<92.0%) to the validated bacterial species within the family Oscillospiraceae. The percentage of conserved protein values between the genome of strain 12CBH8T and that of the validated related taxa were <50%, suggesting that strain 12CBH8T belongs to a novel genus. On the basis of the collected data, strain 2CBH44T represents a novel subspecies of C. secundus, for which the name Coprobacter secundus subsp. similis subsp. nov. (type strain 2CBH44T  = JCM 34079T  = DSM 111570T ) is proposed. Strain 12CBH8T represents a novel species of a novel genus, for which the name Solibaculum mannosilyticum gen. nov., sp. nov. (type strain 12CBH8T  = JCM 34081T  = DSM 111571T ) is proposed.

DOI： 10.1111/1348-0421.12886

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/1348-0421.12886

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society for Microbiology  

Here, we report the complete genome sequence of
<italic>Faecalibacillus intestinalis</italic>
JCM 34082, a member of the family
<italic>Erysipelotrichaceae</italic>
that was isolated from feces from a healthy Japanese woman. The genome assembly comprised 2,869,982 bp, with a G+C content of 29.8%.

DOI： 10.1128/mra.01160-20

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A large variety of microbes are present in the human gut, some of which are considered to interact with each other. Most of these interactions involve bacterial metabolites. Phascolarctobacterium faecium hardly uses carbohydrates for growth and instead uses succinate as a substrate. This study investigated the growth behavior of the co-culture of the succinate-specific utilizer P. faecium and the succinogenic gut commensal Bacteroides thetaiotaomicron. Succinate production by B. thetaiotaomicron supported the growth of P. faecium and concomitant propionate production via the succinate pathway. The succinate produced was completely converted to propionate. This result was comparable with the monoculture of P. faecium in the medium supplemented with 1% (w/v) succinate. We analyzed the transcriptional response (RNA-Seq) between the mono- and co-culture of P. faecium and B. thetaiotaomicron. Comparison of the expression levels of genes of P. faecium between the mono- and co-cultured conditions highlighted that the genes putatively involved in the transportation of succinate were notably expressed under the co-cultured conditions. Differential expression analysis showed that the presence of P. faecium induced changes in the B. thetaiotaomicron transcriptional pattern, for example, expression changes in the genes for vitamin B12 transporters and reduced expression of glutamate-dependent acid resistance system-related genes. Also, transcriptome analysis of P. faecium suggested that glutamate and succinate might be used as sources of succinyl-CoA, an intermediate in the succinate pathway. This study revealed some survival strategies of asaccharolytic bacteria, such as Phascolarctobacterium spp., in the human gut.

DOI： 10.1002/mbo3.1111

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Several Trichonympha protist species in the termite gut have independently acquired Desulfovibrio ectosymbionts in apparently different stages of symbiosis. Here, we obtained the near-complete genome sequence of Desulfovibrio phylotype ZnDsv-02, which attaches to the surface of Trichonympha collaris cells, and compared it with a previously obtained genome sequence of 'Candidatus Desulfovibrio trichonymphae' phylotype Rs-N31, which is almost completely embedded in the cytoplasm of Trichonympha agilis. Single-nucleotide polymorphism analysis indicated that although Rs-N31 is almost clonal, the ZnDsv-02 population on a single host cell is heterogeneous. Despite these differences, the genome of ZnDsv-02 has been reduced to 1.6 Mb, which is comparable to that of Rs-N31 (1.4 Mb), but unlike other known ectosymbionts of protists with a genome similar in size to their free-living relatives. Except for the presence of a lactate utilization pathway, cell-adhesion components and anti-phage defense systems in ZnDsv-02, the overall gene-loss pattern between the two genomes is very similar, including the loss of genes responsive to environmental changes. Our study suggests that genome reduction can occur in ectosymbionts, even when they can be transmitted horizontally and obtain genes via lateral transfer, and that the symbiont genome size depends heavily on their role in the symbiotic system.

DOI： 10.1038/s41396-020-0688-1

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Four strains (9CBEGH2T, 9BBH35, 6BBH38 and 6EGH11) of Gram-stain-positive, obligately anaerobic, rod-shaped bacteria were isolated from faecal samples from healthy Japanese humans. The results of 16S rRNA gene sequence analysis indicated that the four strains represented members of the family Erysipelotrichaceae and formed a monophyletic cluster with 'Absiella argi' strain N6H1-5 (99.4% sequence similarity) and Eubacterium sp. Marseille-P5640 (99.3 %). Eubacterium dolichum JCM 10413T (94.2 %) and Eubacterium tortuosum ATCC 25548T (93.7 %) were located near this monophyletic cluster. The isolates, 9CBEGH2T, 'A. argi' JCM 30884 and Eubacterium sp. Marseille-P5640 shared 98.7-99.1% average nucleotide identity (ANI) with each other. Moreover, the in silico DNA-DNA hybridization (DDH) values among three strains were 88.4-90.6%, indicating that these strains represent the same species. Strain 9CBEGH2T showed 21.5-24.1 % in silico DDH values with other related taxa. In addition, the ANI values between strain 9CBEGH2T and other related taxa ranged from 71.2 % to 73.5 %, indicating that this strain should be considered as representing a novel species on the basis of whole-genome relatedness. Therefore, we formally propose a novel name for 'A. argi' strains identified because the name 'A. argi' has been effectively, but not validly, published since 2017. On the basis of the collected data, strain 9CBEGH2T represents a novel species of a novel genus, for which the name Amedibacterium intestinale gen. nov., sp. nov. is proposed. The type strain of A. intestinale is 9CBEGH2T (=JCM 33778T=DSM 110575T).

DOI： 10.1099/ijsem.0.004215

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Gut microbiota impacts the host metabolome and affects its health span. How bacterial species in the gut influence age-dependent metabolic alteration has not been elucidated. Here we show in Drosophila melanogaster that allantoin, an end product of purine metabolism, is increased during aging in a microbiota-dependent manner. Allantoin levels are low in young flies but are commonly elevated upon lifespan-shortening dietary manipulations such as high-purine, high-sugar, or high-yeast feeding. Removing Acetobacter persici in the Drosophila microbiome attenuated age-dependent allantoin increase. Mono-association with A. persici, but not with Lactobacillus plantarum, increased allantoin in aged flies. A. persici increased allantoin via activation of innate immune signaling IMD pathway in the renal tubules. On the other hand, analysis of bacteria-conditioned diets revealed that L. plantarum can decrease allantoin by reducing purines in the diet. These data together demonstrate species-specific regulations of host purine levels by the gut microbiome.

DOI： 10.1016/j.isci.2020.101477

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Necrotic cells elicit an inflammatory response through their endogenous factors with damage-associated molecular patterns. Blocking apoptosis in Drosophila wings leads to the necrosis-driven systemic immune response by unknown mechanisms. Here, we demonstrate that immune activation in response to necrotic cells is mediated by commensal gut microbiota. Removing the microbiome attenuates hyperactivation of the innate immune signaling IMD pathway in necrosis-induced flies. Necrotic cells in wings trigger Gluconobacter expansion in the gut. An isolated Gluconobacter sp. strain is sufficient for pathological IMD activation in necrosis-induced flies, while it is not inflammatory for control animals. In addition, bacterial colonization shifts the host metabolome and shortens the lifespan of necrosis-induced flies. This study shows that local necrosis triggers a pathological systemic inflammatory response through interaction between the host and the dysbiotic gut microbiome.

DOI： 10.1016/j.celrep.2020.107938

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An obligately anaerobic, Gram-stain-negative, rod or coccobacilli organism was isolated from a faecal sample of a healthy Japanese woman. In the 16S rRNA gene sequence analysis, strain 5BBH33T showed the highest 16S rRNA gene sequence similarity to Dialister succinatiphilus YIT 11850T (95.9 %), Dialister propionicifaciens ADV 1053.03T (94.3 %), Dialister micraerophilus DSM 19965T (93.1 %), Dialister invisus DSM 15470T (92.5 %) and Dialister pneumosintes ATCC 33048T (91.4 %). The hsp60 gene sequence analysis also revealed strain 5BBH33T had relatively low hsp60 gene sequence similarities (74.4-85.3 %) to other Dialister species. Strain 5BBH33T showed 21.8-23.9 % in silico DNA-DNA hybridization values with other Dialister species. In addition, the average nucleotide identity values between strain 5BBH33T and other Dialister species ranged from 68.7-74.2 %, indicating that this strain should be considered as new species based on whole-genome relatedness. Strain 5BBH33T was asaccharolytic and largely unreactive for commercial kit. However, its growth was enhanced by adding 1 % (w/v) succinate to the medium; strain 5BBH33T was able to decarboxylate succinate to propionate. The strain 5BBH33T genome contained the enzymes involved in succinate utilization. These results improve our understanding of succinate-utilizing bacteria. On the basis of the collected data, strain 5BBH33T represents a novel species in the genus Dialister, for which the name Dialister hominis sp. nov. is proposed. The type strain of D. hominis is 5BBH33T (=JCM 33369T=DSM 109768T).

DOI： 10.1099/ijsem.0.003797

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Authorship：Lead author  

DOI： 10.1128/MRA.01630-18

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1038/s41396-018-0297-4

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Other Link： http://www.nature.com/articles/s41396-018-0297-4.pdf

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/femsec/fiy238

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DOI： 10.1099/ijsem.0.003283

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Microbial Ecology  

DOI： 10.1264/jsme2.ME17137

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

The glacier stonefly Andiperla willinki is the largest metazoan inhabiting the Patagonian glaciers. In this study, we analysed the gut microbiome of the aquatic nymphs by 16S rRNA gene amplicon and metagenomic sequencing. The bacterial gut community was consistently dominated by taxa typical of animal digestive tracts, such as Dysgonomonadaceae and Lachnospiraceae, as well as those generally indigenous to glacier environments, such as Polaromonas. Interestingly, the dominant Polaromonas phylotypes detected in the stonefly gut were almost never detected in the glacier surface habitat. Fluorescence in situ hybridization analysis revealed that the bacterial lineages typical of animal guts colonized the gut wall in a co-aggregated form, while Polaromonas cells were not included in the aggregates. Draft genomes of several dominant bacterial lineages were reconstructed from metagenomic datasets and indicated that the predominant Dysgonomonadaceae bacterium is capable of degrading various polysaccharides derived from host-ingested food, such as algae, and that other dominant bacterial lineages ferment saccharides liberated by the polysaccharide degradation. Our results suggest that the gut bacteria-host association in the glacier stonefly contributes to host nutrition as well as material cycles in the glacier environment.

DOI： 10.1111/1462-2920.14420

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1264/jsme2.ME16158

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/femsec/fiv003

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