Bacteriophages are promising antibacterial agents for managing acne vulgaris caused by Cutibacterium acnes, particularly given increasing antibiotic resistance. Here, we isolated and characterized two lytic Cutibacterium phages, NS-ph1 and NS-ph2, from acne lesions. Both bacteriophages exhibited a broad lytic spectrum, with a high activity against 27 C. acnes strains. Adsorption assays indicated rapid attachment and one-step growth experiments revealed latent periods of 4 h (NS-ph1) and 2 h (NS-ph2) and burst sizes of 70 and 59 PFU per infected cell, respectively. After long-term storage at room temperature, both phages retained infectivity for 3 months. Genome sequencing revealed linear dsDNA genomes of 29,490 bp (NS-ph1) and 29,189 bp (NS-ph2) with 51 and 46 predicted ORFs, respectively, and no tRNAs. No genes associated with lysogeny, toxins, or antibiotic resistance were detected. Comparative genomics placed both phages within the genus Pahexavirus. Together, these data expand the diversity of Pahexavirus and provide two well-characterized lytic candidates for further evaluation in anti-acne phage therapy.

Enterococcus faecalis is an important opportunistic pathogen associated with persistent oral infections, biofilm formation, and antimicrobial tolerance, which makes phages targeting this species of both therapeutic and evolutionary interest. Here, we describe the isolation and characterization of Abitsa, a novel lytic Enterococcus phage representing a new species within the genus Efquatrovirus. Abitsa formed small plaques and displayed siphovirus-like morphology. It showed an optimal multiplicity of infection of 0.01, a short latent period of 10 min and a burst size of 28 ± 5 virions per infected cell. The phage efficiently suppressed planktonic growth of E. faecalis over a broad multiplicity of infection (MOI) range and significantly disrupted pre-formed biofilms, with the strongest effect observed at MOI 0.1, resulting in an 82.14% reduction in biofilm biomass. Abitsa remained stable at pH 4–8, at 5–50 °C for 1 h, and in up to 75% chloroform, but exhibited a narrow host range, lysing only one additional clinical E. faecalis isolate among 34 tested enterococcal isolates. Genome analysis showed that Abitsa has a 41,581-bp linear genome lacking lysogeny-associated genes and represents a novel Efquatrovirus species. Comparative structural and phylogenetic analyses additionally supported mosaic evolution and extensive domain shuffling in receptor-binding and lysis-related proteins of Efquatrovirus-like phages. Together, these results identify Abitsa as a biologically unusual and evolutionarily informative lytic phage with antibiofilm activity.

The genus Parabacteroides comprises widespread gastrointestinal commensals, known to produce immunomodulatory molecules and extracellular vesicles, yet its full diversity is incompletely cataloged. This study describes strain ASD2025T, isolated from healthy child feces, using a polyphasic taxonomic approach including phenotypic profiling, chemotaxonomy, and comparative genomics. Cells were non-motile, polymorphic rods that produced extracellular vesicles. Phylogenomic analysis placed ASD2025T within the genus Parabacteroides within a species complex consisting of P. acidifaciens, P. hominis, "P. massiliensis", P. merdae, and P. johnsonii, with average nucleotide identities to the type strains of 85.5-89.9%. The large genome (5.16 Mbp, 46.2% GC content) contained integrative conjugative elements harboring antibiotic resistance genes and hankyphage-related prophage. The strain produced succinate as the major metabolic end product, and its major fatty acids were anteiso-C15:0, iso-C17:0 3-OH, and C15:0. Conditioned medium from ASD2025T antagonized the interleukin-8 response caused by E. coli lipopolysaccharide in HT29 cells. The majority of related metagenome-assembled genomes originate from mouse microbiomes. Based on these distinct characteristics, strain ASD2025T (=VKM B-3926T = JCM 37967T) represents a novel species of the genus Parabacteroides, for which the name Parabacteroides vesiculifaciens sp. nov. is proposed.

BackgroundThe immunomodulatory effects of gut Bacteroides are typically attributed to surface polysaccharides signaling through TLR2 and TLR4, and to outer membrane vesicles (OMVs) that traffic effector molecules to host cells. However, these bacteria also secrete a wide array of metabolites, including short-chain fatty acids (SCFAs), medium-chain fatty acids (MCFAs), phenolic compounds, and aldehydes, whose contributions to immune modulation remain underexplored. Moreover, it is unclear whether different Bacteroides and Phocaeicola species share similar immunomodulatory profiles or display species- and strain-specific activities.MethodsWe cultivated 18 strains of Bacteroides and Phocaeicola, collected their conditioned media, and applied them to HT-29 intestinal epithelial cells. TLR2 and TLR4 gene expression and IL-8 secretion were measured under basal and LPS-stimulated conditions. The volatile metabolome was characterized using HS-GC/MS, and the data were integrated with cellular responses.ResultsThe strains induced strikingly divergent effects, ranging from strong suppression to marked induction of TLR2/TLR4 expression and IL-8 production. Metabolomic profiling revealed that while SCFAs and MCFAs were associated with anti-inflammatory outcomes, the presence of phenolic compounds and aldehydes correlated with pro-inflammatory effects. Integration of metabolomic and cellular data allowed us to classify the strains into three functional categories: anti-inflammatory (e.g., B. uniformis EBA 5-20), pro-inflammatory (e.g., B. thetaiotaomicron 6-237), and strains with context-dependent mixed effects.ConclusionThe immunomodulatory activity of gut Bacteroides and Phocaeicola cannot be predicted solely by their taxonomic affiliation; rather, it depends on the specific repertoire of secreted metabolites and their interplay with host pathways. Evaluating both metabolomic profiles and receptor-mediated responses provides a rational basis for selecting candidate probiotics for personalized microbiome modulation.

An obligate anaerobic, Gram-negative rod-shaped bacterial strain designated AD58T was isolated from the feces of a 3-year-old boy with atopic dermatitis. The closest species is Parabacteroides fecalis with 96.98

Antibiotic-resistant Pseudomonas aeruginosa presents a critical global health challenge, particularly in hospital-acquired infections. Bacteriophages offer a promising therapeutic avenue due to their ability to target and lyse resistant strains. This study characterizes Pseudomonas phage Banzai, a newly isolated Pbunavirus (family Lindbergviridae) with lytic activity against multiple P. aeruginosa isolates, including multidrug-resistant strains. Genomic analysis revealed a 66,189 bp genome, lacking antibiotic resistance or virulence factors, and suggested a headful packaging mechanism and the presence of a bidirectional component in the replication. In vivo experiments using Galleria mellonella showed therapeutic potential, significantly improving larval survival (87% at 24 h). Host range analysis revealed activity against 13 of 30 P. aeruginosa isolates, including members of O1, O3, O5 and O6 in silico predicted serogroups. Phylogenomic analyses place phage Banzai within the genus Pbunavirus, sharing 94.8% intergenomic similarity with its closest relatives, supporting its classification as a novel species. These findings highlight phage Banzai as a potential candidate for phage therapy, demonstrating genomic stability, a strictly lytic lifestyle, and in vivo efficacy.

Inflammatory bowel disease (IBD) is highly prevalent globally and, in the majority of cases, remains asymptomatic during its initial stages. The gastrointestinal microbiota secretes volatile organic compounds (VOCs), and their composition alters in IBD. The examination of VOCs could prove beneficial in complementing diagnostic techniques to facilitate the early identification of IBD risk. In this protocol, a model of sodium dextran sulfate (DSS)-induced colitis in rats was successfully implemented for the non-invasive metabolomic assessment of different stages of inflammation. Headspace-gas chromatography-mass spectrometry (HS-GC-MS) was used as a non-invasive method for inflammation assessment at early and remission stages. The disease activity index (DAI) and histological method were employed to assess intestinal inflammation. The HS-GC-MS method demonstrated high sensitivity to intestine inflammation, confirmed by DAI and histology assay, in the acute and remission stages, identifying changes in the relative content of VOCs in stools. HS-GC-MS may be a useful and non-invasive method for IBD diagnostics and therapy effectiveness control. Key features • Experiments performed in vivo to better control DSS-induced colon damage and to aid the study of IBD development in humans. • Optimized for the following organisms: Wistar rats and C57BL/6 mice. • An easily assessed disease activity index (DAI) (weight loss, stool consistency, degree of fecal occult blood) and histopathological examination are suggested for additional IBD confirmation. • Enables VOC testing with relatively small stool samples.

Bulleidia extructa strain PP_925, isolated from the periodontal pocket of a patient with periodontitis, is a Gram-positive Bacillota with an unusually compact genome of 1.38 Mb. Phylogenomic analyses place PP_925 within Erysipelotrichales and show close relatedness of Bulleidia to Solobacterium and Lactimicrobium, as well as the existence of previously undescribed related clades. The metabolic repertoire of PP_925 is strongly reduced: it retains glycolysis, the phosphotransacetylase-acetate kinase pathway, and arginine catabolism but lacks the tricarboxylic acid cycle and most de novo biosynthetic pathways for amino acids, nucleotides, fatty acids, cofactors, and vitamins, implying reliance on salvage and cross-feeding. Phylogenetic inference indicates independent peptidoglycan losses in multiple mycoplasma Erysipelotrichia-related lineages, while PP_925 has retained an ancestral Gram-positive cell wall despite extensive genomic reduction. The genome preserves systems crucial for host interaction and adaptability, including a horizontally acquired tad locus encoding type IV pili, a comG competence system, and several adherence-associated virulence factors. Defense mechanisms are diverse and include a CRISPR-Cas II-A system, a type II restriction-modification module adjacent to Gao_Qat-like genes, and the Wadjet system in a genome without prophages; CRISPR spacers indicate repeated encounters with Bacillota phages. Comparative genomics of PP_925 and related strains reveals a small core genome with lineage-specific adhesion and defense modules, indicating recent shared ancestry combined with adaptive flexibility under substantial genome reduction.

IntroductionBacteroides fragilis (Bf)’s T6SS locus has been characterized and shown to have functional activity in competition experiments. It has been demonstrated that symbiont nontoxigenic Bf strains have a more effective “weapon” effect on pathogenic Bf, which is realized through the activity of effector-immune (E-I) protein pairs. Intensive study of the T6SS structure has led to an understanding of certain issues related to its functional activity, but the exact regulatory mechanisms of E-I protein pair activity remain unclear. Proteomic annotation of T6SS components and detailed descriptions of all immune-effector pairs are currently available. In this research, we performed detailed proteogenomic analysis and subsequent proteomic annotation of the T6SS components of the toxigenic Bf BOB25.Material and methodsFractionated cells, cultivated media and vesicles were prepared for proteome analysis by HPLC-MS/MS. Proteogenomic annotation and comparative genomic study of the T6SS loci of the toxigenic Bf BOB25 were carried out by comparison with the reference genomes of the following Bf strains: JIM10, NCTC 9343 and 638R.ResultsAccording to the data obtained, T6SS components were represented in all types of the analysed samples. The following components of the T6SS were identified in culture media and cells: ClpV (TssH), TssK, TssC, TssB, Hcp (TssD), and TetR. The predicted effector protein AKA51715.1 (VU15_08315) was also detected in media. The greatest amount of T6SS proteins, including the Hcp protein, was detected in the vesicle samples, which was also observed by TEM. Potential effectors, including AKA51715.1 (VU15_08315), AKA51716.1 (VU15_08320), AKA51728.1 (VU15_08385) and the immune protein AKA51727.1 (VU15_08380), were detected in vesicles.DiscussionThe presence of the immune and effector proteins in the Bf secretome indicates the high activity of the T6SS without bacterial competition. It is possible that the T6SS is also used by bacteria to regulate population size by altering the activity of different repertoires of E-I pairs.

Bacteriophages are powerful drivers of microbial evolution and are increasingly explored as alternatives to antibiotics against multidrug-resistant pathogens such as Pseudomonas aeruginosa. Here, we describe the isolation, phenotypic characterization and genomic, structural and evolutionary analysis of Pseudomonas phage Adele, a lytic myovirus representing a novel species within the genus Pakpunavirus (family Vandenendeviridae). Phage Adele exhibits a short latent period of 20 min, a burst size of 59 ± 11 virions per infected cell and a high virulence index, efficiently lysing non-O11 Pseudomonas aeruginosa strains and reducing biofilm biomass. In vivo, Adele confers marked protection in a Galleria mellonella infection model. Phylogenetic reconstruction, synteny analysis and structural modeling demonstrate the relatedness of Vandenendeviridae to phages of the Andersonviridae and Vequintavirinae clades, pointing to a stable, ancestral virion architecture that has undergone lineage-specific elaborations, including the duplication and divergence of tail tube proteins. The tail assembly chaperone gene employs a conserved −1 programmed ribosomal frameshift. Phage Adele encodes an elaborate set of metabolic reprogramming and anti-defense systems, reflecting extensive horizontal gene transfer. The combination of a conserved structural architecture and mosaic genome establishes Adele as an exemplary system for studying modular evolution in phages, alongside its demonstrated therapeutic efficacy.

Vakcinaciya yavlyaetsya effektivnym sredstvom preduprezhdeniya zabolevaniya koklyushnoj infekciej. Cel'yu raboty bylo usovershenstvovanie vakcinnyh preparatov v RF, v tom chisle aktualizaciya proizvodstvennyh vakcinnyh shtammov. Izuchali shtammy B. pertussis, vydelennye v g. Moskve, Voronezhskoj, Novosibirskoj, Ul'yanovskoj i CHelyabinskoj oblastyah, i vosem' proizvodstvennyh shtammov dlya adsorbirovannoj koklyushno-difterijno-stolbnyachnoj (AKDS) vakciny. Dlya genotipirovaniya ispol'zovali mul'tilokusnoe antigennoe sikvens-tipirovanie (MAST) i polnogenomnoe mul'tilokusnoe sikvens-tipirovanie (wgMLST). Izucheny kul'tural'no-morfologicheskie, fermentantivnye, serologicheskie i genotipicheskie svojstva shtammov B. pertussis — kandidatov v proizvodstvennye vakcinnye shtammy i proveden sravnitel'nyj analiz genotipicheskih svojstv etih shtammov i proizvodstvennyh vakcinnyh shtammov B. pertussis dlya vakciny AKDS. Kandidatnye shtammy yavlyayutsya predstavitelyami chetyrekh genotipov — ptxA1/ptxV2/ptxS2/ptxR3/fim2-2/fim3-2/prn2, ptxA1/ptxV2/ptxS2/ptxR3/fim2-2/fim3-2/prn9, ptxA1/ptxV2/ptxS2/ptxR3/fim2-1/fim3-1/prn1 i ptxA1/ptxV2/ptxS2/ptxR3/fim2-2/fim3-1/prn2. Proizvodstvennye vakcinnye shtammy prinadlezhali k drugim shesti genotipam: ptxA2/ptxV1/ptxS1/ptxR1/ fim2-1/fim3-1/prn1, ptxA2/ptxV2/ptxS1/ptxR2/fim2-1/fim3-1/prn1, ptxA4/ptxV1/ptxS1/ptxR2/fim2-1/fim3-1/prn1, ptxA2/ptxV2/ptxS1/ptxR1/fim2-1/fim3-1/prn1, ptxA4/ptxV2/ptxS1/ptxR2/fim2-1/fim3-1/prn1 i ptxA1/ptxV2/ptxS1/ptxR1/fim2-1/fim3-1/prn1. S pomoshch'yu wgMLST ustanovlena prinadlezhnost' vsekh kandidatnyh shtammov B. pertussis k ST2.

Inflammatory bowel diseases are characterized by chronic intestinal inflammation and alterations in the gut microbiota composition. Bacteroides fragilis, which secretes outer membrane vesicles (OMVs) with polysaccharide A (PSA), can moderate the inflammatory response and possibly alter the microbiota composition. In this study, we created a murine model of chronic sodium dextran sulfate (DSS)-induced intestinal colitis and treated it with B. fragilis OMVs. We monitored the efficiency of OMV therapy by determining the disease activity index (DAI) and performing histological examination (HE) of the intestine before and after vesicle exposure. We also analyzed the microbiota composition using 16S rRNA gene sequencing. Finally, we evaluated the volatile compound composition in the animals' stools by HS-GC/MS to assess the functional activity of the microbiota. We observed more effective intestinal repair after OMV treatment according to the DAI and HE. A metabolomic study also revealed changes in the functional activity of the microbiota, with a predominance of phenol and pentanoic acid in the control group compared to the group treated with DSS and the group treated with OMVs (DSS OMVs). We also observed a positive correlation of these metabolites with Saccharibacteria and Acetivibrio in the control group, whereas in the DSS group, there was a negative correlation of phenol and pentanoic acid with Lactococcus and Romboutsia. According to the metabolome and sequencing data, the microbiota composition of the DSS-treated OMV group was intermediate between that of the control and DSS groups. OMVs not only have an anti-inflammatory effect but also contribute to the recovery of the microbiota composition.IMPORTANCEBacteroides fragilis vesicles contain superficially localized polysaccharide A (PSA), which has unique immune-modulating properties. Isolated PSA can prevent chemically induced colitis in a murine model. Outer membrane vesicles (OMVs) also contain digestive enzymes and volatile metabolites that can complement the anti-inflammatory properties of PSA. OMVs showed high therapeutic activity against sodium dextran sulfate-induced colitis, as confirmed by histological assays. 16S rRNA sequencing of fecal samples from different inflammatory stages, supplemented with comprehensive metabolome analysis of volatile compounds conducted by HS-GC/MS, revealed structural and functional alterations in the microbiota composition under the influence of OMVs. Correlation analysis of the OMV-treated and untreated experimental animal groups revealed associations of phenol and pentanoic acid with Lactococcus, Romboutsia, Saccharibacteria, and Acetivibrio.

Vaccination is an effective means of preventing pertussis infection. The purpose of this work was to improve vaccines available in the Russian Federation in general and actualize vaccine strains used for the production thereof in particular. We studied B. pertussis strains isolated in Moscow, Voronezh, Novosibirsk, Ulyanovsk and Chelyabinsk regions, and eight production strains part of the adsorbed diphtheria-pertussis-tetanus (DPT) vaccine. Multilocus antigenic sequence typing (MAST) and whole genome multilocus sequence typing (wgMLST) were used for genotyping. We studied cultural morphological, enzymatic, serological, and genotypic properties of the candidate B. pertussis strains, and compared their genotypic properties to those of B. pertussis vaccine strains from the current composition of the DPT vaccine. Candidate strains belong to four genotypes: ptxА1/ptxВ2/ptxС2/ptxР3/fim2-2/fim3-2/prn2, ptxА1/ptxВ2/ptxС2/ptxР3/fim2-2/fim3-2/prn9, ptxА1/ptxВ2/ptxС2/ptxР3/fim2-1/fim3-1/prn1 and ptxА1/ptxВ2/ptxС2/ptxР3/fim2-2/fim3-1/prn2. Current vaccine strains were from other six genotypes: ptxА2/ptxВ1/ptxС1/ptxР1/fim2-1/fim3-1/prn1, ptxА2/ptxВ2/ptxС1/ptxР2/fim2-1/fim3-1/prn1, ptxА4/ptxВ1/ptxС1/ptxР2/fim2-1/fim3-1/prn1, ptxА2/ptxВ2/ptxС1/ptxР1/fim2-1/fim3-1/prn1, ptxА4/ptxВ2/ptxС1/ptxР2/fim2-1/fim3-1/prn1 and ptxА1/ptxВ2/ptxС1/ptxР1/fim2-1/fim3-1/prn1. With the help of wgMLST, we established affiliation of all candidate strains of B. pertussis to ST2.

Microorganisms and their hosts communicate with each other by secreting numerous components. This cross-kingdom cell-to-cell signaling involves proteins and small molecules, such as metabolites. These compounds can be secreted across the membrane via numerous transporters and may also be packaged in outer membrane vesicles (OMVs). Among the secreted components, volatile compounds (VOCs) are of particular interest, including butyrate and propionate, which have proven effects on intestinal, immune, and stem cells. Besides short fatty acids, other groups of volatile compounds can be either freely secreted or contained in OMVs. As vesicles might extend their activity far beyond the gastrointestinal tract, study of their cargo, including VOCs, is even more pertinent. This paper is devoted to the VOCs secretome of the Bacteroides genus. Although these bacteria are highly presented in the intestinal microbiota and are known to influence human physiology, their volatile secretome has been studied relatively poorly. The 16 most well-represented Bacteroides species were cultivated; their OMVs were isolated and characterized by NTA and TEM to determine particle morphology and their concentration. In order to analyze the VOCs secretome, we propose a headspace extraction with GC–MS analysis as a new tool for sample preparation and analysis of volatile compounds in culture media and isolated bacterial OMVs. A wide range of released VOCs, both previously characterized and newly described, have been revealed in media after cultivation. We identified more than 60 components of the volatile metabolome in bacterial media, including fatty acids, amino acids, and phenol derivatives, aldehydes and other components. We found active butyrate and indol producers among the analyzed Bacteroides species. For a number of Bacteroides species, OMVs have been isolated and characterized here for the first time as well as volatile compounds analysis in OMVs. We observed a completely different distribution of VOC in vesicles compared to the bacterial media for all analyzed Bacteroides species, including almost complete absence of fatty acids in vesicles. This article provides a comprehensive analysis of the VOCs secreted by Bacteroides species and explores new perspectives in the study of bacterial secretomes in relation the intercellular communication.

Bakterii roda Aerococcus chasto associirovany s infekciyami mochevyvodyashchih putej i krovotoka u cheloveka. SHtamm Aerococcus sp. 1KP-2016, vydelennyj iz lejkocitarnogo sloya krovi, obladal posledovatel'nost'yu 16S rRNK, sovpadayushchej na 98,7% i menee s ranee opisannymi predstavitelyami dannogo roda. Cel'yu raboty bylo provesti polnogenomnoe sekvenirovanie Aerococcus 1KP-2016 s posleduyushchej filogeneticheskoj rekonstrukciej. Pokazano, chto Aerococcus 1KP-2016 yavlyaetsya predstavitelem novogo vida roda Aerococcus, naibolee blizkogo k Aerococcus viridans i Aerococcus urinaeequi. Genomnaya posledovatel'nost', imeyushchaya dlinu 2,042 mln p.n. i GC-sostav 38,5%, deponirovana v DBJ/EMBL/GenBank pod identifikatorom NEEY00000000.

Aerococcus genus bacteria are often associated with human urinary tract and bloodstream infections. The Aerococcus sp. 1KP-2016 strain isolated from the buffy coat had the 16S rRNA sequence that was a 98.7% (and less) match with the previously described members of this genus. The purpose of this study was to perform whole genome sequencing of Aerococcus 1KP-2016 followed by phylogenetic reconstruction. We have shown that Aerococcus 1KP-2016 belongs to the new species of the Aerococcus genus that is closest to Aerococcus viridans and Aerococcus urinaeequi. The genomic sequence, which consists of 2.042 million bps with GC content at 38.5%, was deposited in the DBJ/EMBL/GenBank under identifier NEEY00000000.

Nechuvstvitel'nye k antibiotikam shtammy Pseudomonas aeruginosa predstavlyayut soboj global'nuyu problemu v zdravoohranenii. Issledovanie mekhanizmov vozniknoveniya rezistentnosti lezhit v osnove razrabotki sposobov bor'by s P. aeruginosa. Cel'yu raboty bylo issledovat' vozniknovenie kross-rezistentnosti u P. aeruginosa v processe adaptacii k populyarnomu antibiotiku meropenemu. Ob"ektami issledovaniya byli obrazcy P. aeruginosa, poluchennye pri roste referentnogo shtamma P. aeruginosa ATCC 27853 na srede s vozrastayushchej koncentraciej meropenema. CHuvstvitel'nost' izolyatov k karbapenemam i kolistinu opredelyali pri pomoshchi razvedeniya v agare, chuvstvitel'nost' k kolistinu ocenivali metodom serijnyh razvedenij. Bylo polucheno 93 izolyata P. aeruginosa, dva iz kotoryh imeli snizhennuyu chuvstvitel'nost' odnovremenno k karbapenemam (meropenem, imipenem) i kolistinu. Genomy izolyatov sekvenirovali na polnogenomnom sekvenatore MGISEQ-2000; obnaruzheny missens-mutacii v genah oprD i mexD i nonsens-mutaciya v phoQ. Poluchnnye rezul'taty pokazyvayut, chto pri vozdejstvii meropenema na shtammy P. aeruginosa mozhet razvivat'sya kross-rezistentnost' k kolistinu — preparatu rezerva dlya lecheniya sinegnojnoj infekcii.

Rezistentnyye k karbapenemam shtammy Pseudomonas aeruginosa rastsenivayut v kachestve kriticheski opasnykh patogenov pervogo urovnya prioriteta. Rasshifrovka mekhanizmov formirovaniya ustoychivosti k karbapenemam yavlyayetsya aktual'noy zadachey sovremennoy meditsinskoy nauki. Tsel'yu raboty bylo opisat' raznoobraziye i zakrepleniye mutatsiy, assotsiirovannykh s formirovaniyem karbapenemrezistentnosti v protsesse adaptatsii P. aeruginosa k povyshayushchimsya kontsentratsiyam meropenema. Ob"yektami issledovaniya byli izolyaty P. aeruginosa, poluchennyye pri roste referentnogo shtamma P. aeruginosa ATCC 27853 v gradiyente vozrastayushchikh kontsentratsiy meropenema. Otsenku chuvstvitel'nosti izolyatov k meropenemu vypolnyali pri pomoshchi ye-testov (epsilometricheskiy metod) s meropenemom i pri pomoshchi metoda dilyutsii antibiotika v agare. Genomy izolyatov byli sekvenirovany na polnogenomnom sekvenatore MGISEQ-2000. Poluchennyye rezul'taty pokazali, chto formirovaniye vysokikh urovney rezistentnosti k meropenemu u P. aeruginosa v eksperimente proiskhodit v korotkiye sroki (6 sutok). Evolyutsiya rezistentnosti sopryazhena s protsessom klonirovaniya, pri kotorom proiskhodit vozniknoveniye mnozhestva klonov s razlichnymi genotipami. Osnovoy klonirovaniya yavlyayetsya mutagenez, v kotoryy vovlecheny 11 genov, vklyuchaya oprD, pbuE, nalD, nalC, spoT, mlaA, mexD, mexR, oprM, mraY, pbp3. Chast' obrazovavshikhsya klonov, nezavisimo ot urovnya ikh rezistentnosti k meropenemu, ne poluchayut progressivnogo razvitiya i vytesnyayutsya boleye uspeshnymi klonami.

The carbapenem-resistant strains of Pseudomonas aeruginosa are considered as the dangerous pathogens of critical priority. Deciphering the mechanisms underlying the development of carbopenem resistance is an urgent challenge faced by modern medical science. The study was aimed to describe the diversity and fixation of mutations associated with the development of carbapenem resistance during the P. aeruginosa adaptation to the increasing meropenem concentrations. The objects of the study were P. aeruginosa isolates obtained by growing the ATCC 27853 P. aeruginosa reference strain exposed to increasing concentrations of meropenem. The isolates were tested for meropenem susceptibility using E-tests (Epsilometer tests) and by the agar dilution method. Genomes of the isolates were sequenced in the MGISEQ-2000 whole-genome sequencer. The findings show that in experimental settings P. aeruginosa develops high meropenem resistance very quickly (in 6 days). Evolution of resistance is associated with cloning involving the emergence of multiple clones with various genotypes. Mutagenesis that involves 11 genes, including oprD, pbuE, nalD, nalC, spoT, mlaA, mexD, mexR, oprM, mraY, pbp3, provides the basis for cloning. Regardless of the levels of their meropenem resistance, some of the emerging clones do not progressively develop and are replaced by more successful clones.

Three novel strains of Gram-stain-negative, obligately anaerobic, spore-forming straight or slightly curved rods with pointed ends occurring singly or in pairs were isolated from the faeces of healthy human children. The strains were characterized by mesophilic fermentative metabolism and production of acetate, ethanol and H2 as the end metabolic products. Strains ASD3451 and ASD5720T were motile, fermented lactose and raffinose, and weakly fermented maltose. Strain ASD4241T was non-motile and did not ferment the carbohydrates listed above but fermented starch. Strains ASD3451 and ASD5720T shared average nucleotide identity higher than 98.5 % with each other, while ASD4241T had only 88.5-89 % identity to them. Based on phylogenetic and chemotaxonomic analyses, we propose Diplocloster agilis gen. nov., sp. nov. (ASD5720T=JCM 34353T=VKM B-3497T) and Diplocloster modestus sp. nov. (ASD4241T=JCM 34351T=VKM B-3498T) within the family Lachnospiraceae.