Anaerobes Dotaz Zobrazit nápovědu
The cultivation and investigation of strictly anaerobic microorganisms belong to the fields of anaerobic microbial physiology, microbiology, and biotechnology. Anaerobic cultivation methods differ from classic microbiological techniques in several aspects. The requirement for special instruments, which are designed to prevent the contact of the specimen with air/molecular oxygen by different means of manipulation, makes this field more challenging for general research compared to working with aerobic microorganisms. Anaerobic microbiological methods are required for many purposes, such as for the isolation and characterization of new species and their physiological examination, as well as for anaerobic biotechnological applications or medical indications. This review presents the historical development of methods for the cultivation of strictly anaerobic microorganisms focusing on methanogenic archaea, anaerobic cultivation methods that are still widely used today, novel methods for anaerobic cultivation, and almost forgotten, but still relevant, techniques.
- Klíčová slova
- anaerobes, biogas, cultivation methods, methane, methanogens,
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
BACKGROUND: In order to start to understand the function of individual members of gut microbiota, we cultured, sequenced and analysed bacterial anaerobes from chicken caecum. RESULTS: Altogether 204 isolates from chicken caecum were obtained in pure cultures using Wilkins-Chalgren anaerobe agar and anaerobic growth conditions. Genomes of all the isolates were determined using the NextSeq platform and subjected to bioinformatic analysis. Among 204 sequenced isolates we identified 133 different strains belonging to seven different phyla - Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, Verrucomicrobia, Elusimicrobia and Synergistetes. Genome sizes ranged from 1.51 Mb in Elusimicrobium minutum to 6.70 Mb in Bacteroides ovatus. Clustering based on the presence of protein coding genes showed that isolates from phyla Proteobacteria, Verrucomicrobia, Elusimicrobia and Synergistetes did not cluster with the remaining isolates. Firmicutes split into families Lactobacillaceae, Enterococcaceae, Veillonellaceae and order Clostridiales from which the Clostridium perfringens isolates formed a distinct sub-cluster. All Bacteroidetes isolates formed a separate cluster showing similar genetic composition in all isolates but distinct from the rest of the gut anaerobes. The majority of Actinobacteria clustered closely together except for the representatives of genus Gordonibacter showing that the genome of this genus differs from the rest of Actinobacteria sequenced in this study. Representatives of Bacteroidetes commonly encoded proteins (collagenase, hemagglutinin, hemolysin, hyaluronidase, heparinases, chondroitinase, mucin-desulfating sulfatase or glutamate decarboxylase) that may enable them to interact with their host. Aerotolerance was recorded in Akkermansia and Cloacibacillus and was also common among representatives of Bacteroidetes. On the other hand, Elusimicrobium and the majority of Clostridiales were highly sensitive to air exposure despite their potential for spore formation. CONCLUSIONS: Major gut microbiota members utilise different strategies for gut colonisation. High oxygen sensitivity of Firmicutes may explain their commonly reported decrease after oxidative burst during gut inflammation.
- Klíčová slova
- Anaerobe, Butyrate, Chicken, Host-microbiota interactions, Metabolic pathway, Microbiome, Microbiota, Propionate, Whole genome sequencing,
- MeSH
- anaerobní bakterie genetika izolace a purifikace MeSH
- cékum mikrobiologie MeSH
- délka genomu MeSH
- DNA bakterií genetika MeSH
- fylogeneze MeSH
- kur domácí * MeSH
- sekvenování celého genomu metody MeSH
- střevní mikroflóra MeSH
- vysoce účinné nukleotidové sekvenování MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- DNA bakterií MeSH
Cryoconite holes are small ponds present on the surface of most glaciers filled with meltwater and sediment at the bottom. Although they are characterized by extreme conditions, they host bacterial communities with high taxonomic and functional biodiversity. Despite that evidence for a potential niche for anaerobic microorganisms and anaerobic processes has recently emerged, the composition of the microbial communities of the cryoconite reported so far has not shown the relevant presence of anaerobic taxa. We hypothesize that this is due to the lower growth yield of anaerobes compared to aerobic microorganisms. In this work, we aim at evaluating whether the anaerobic bacterial community represents a relevant fraction of the biodiversity of the cryoconite and at describing its structure and functions. We collected sediment samples from cryoconite holes on the Forni Glacier (Italy) and sequenced both 16S rRNA amplicon genes and 16S rRNA amplicon transcripts at different times of the day along a clear summer day. Results showed that a relevant fraction of taxa has been detected only by 16S rRNA transcripts and was undetectable in 16S rRNA gene amplicons. Furthermore, in the transcript approach, anaerobic taxa were overrepresented compared with DNA sequencing. The metatranscriptomics approach was used also to investigate the expression of the main metabolic functions. Results showed the occurrence of syntrophic and commensalism relationships among fermentative bacteria, hydrogenothrophs, and consumers of fermentation end products, which have never been reported so far in cryoconite. IMPORTANCE Recent evidence disclosed the presence of a potential niche for anaerobic microorganisms and anaerobic processes in supraglacial sediments (cryoconite), but a detailed description of the structure and functions of the anaerobic population is still lacking. This work used rRNA and mRNA sequencing and demonstrated that anaerobes are very active in these environments and represent a relevant albeit neglected part of the ecosystem functions in these environments.
- Klíčová slova
- cryoconite, extremophiles, metatranscriptomics,
- Publikační typ
- časopisecké články MeSH
INTRODUCTION: Despite being implicated in a wide spectrum of community- and healthcare-acquired infections, anaerobes have not yet been incorporated into systematic surveillance programs in Europe. METHODS: We conducted a multicentre retrospective observational study analysing all anaerobic strains isolated from blood cultures in 44 European Hospital Centres over a 4-y period (2020-2023). Diagnostic approach, epidemiology, and antimicrobial susceptibility according to EUCAST v. 15.0 were investigated. RESULTS: Our study included 14,527 anaerobes, most of which were Gram-positive (45%) or Gram-negative (40%) bacilli. MALDI-TOF coupled to mass spectrometry was the most widely used tool for species identification (98%). Antimicrobial susceptibility testing was performed in the vast majority of centres, using mostly gradient diffusion strip (77%) and disk diffusion (45%) methods according to EUCAST guidelines. The most prevalent species were Cutibacterium acnes (18.7%), Bacteroides fragilis (16.3%), Clostridium perfringens (5.3%), Bacteroides thetaiotaomicron (4.2%), Fusobacterium nucleatum (3.5%), and Parvimonas micra (3.4%). C. acnes showed high resistance to benzylpenicillin (18%), clindamycin (39%), and imipenem (19% and 13% by MIC methods and disk diffusion, respectively). B. fragilis showed high resistance to amoxicillin/clavulanate (24%), piperacillin/tazobactam (22% and 14% by MIC methods and disk diffusion, respectively), clindamycin (22% by both MIC methods and disk diffusion), meropenem (13%), and metronidazole (10%, only by disk diffusion). A similar resistance pattern was observed in B. thetaiotaomicron, Bacteroides ovatus, and Parabacteroides distasonis. C. perfringens showed high resistance to clindamycin (69% and 45% by MIC methods and disk diffusion, respectively), while benzylpenicillin and metronidazole maintained over 90% activity. F. nucleatum showed high resistance to benzylpenicillin (11%), while Fusobacterium necrophorum showed alarming rates of resistance to clindamycin (12%), meropenem (16%) and metronidazole (11%). CONCLUSIONS: This study presented an up-to-date analysis of the diagnostics and epidemiology of anaerobic bacteria in Europe, providing insights for future comparative analyses and the development of antimicrobial diagnostic and management strategies, as well as the optimization of current antibiotic treatments.
- Klíčová slova
- Anaerobes, Antimicrobial resistance, Bacteroides, Blood culture, Clostridium, Sepsis,
- MeSH
- anaerobní bakterie * účinky léků izolace a purifikace klasifikace MeSH
- antibakteriální látky farmakologie MeSH
- bakteriální infekce * epidemiologie diagnóza mikrobiologie MeSH
- lidé MeSH
- mikrobiální testy citlivosti MeSH
- retrospektivní studie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- pozorovací studie MeSH
- Geografické názvy
- Evropa epidemiologie MeSH
- Názvy látek
- antibakteriální látky MeSH
Chicks in commercial production are highly sensitive to enteric infections and their resistance can be increased by administration of complex adult microbiota. However, it is not known which adult microbiota members are capable of colonising the caecum of newly hatched chicks. In this study, we therefore orally inoculated chicks with pure cultures of 76 different bacterial isolates originating from chicken caecum on day 1 of life and determined their ability to colonise seven days later. The caecum of newly hatched chickens could be colonised by bacteria belonging to phyla Bacteroidetes, Proteobacteria, Synergistetes, or Verrucomicrobia, and isolates from class Negativicutes (phylum Firmicutes). On the other hand, we did not record colonisation with isolates from phyla Actinobacteria and Firmicutes (except for Negativicutes), including isolates from families Lachnospiraceae, Ruminococcaceae, Erysipelotrichaceae, and Lactobacillaceae. Representatives of genera commonly used in probiotics such as Lactobacillus, Enterococcus, or Bacillus therefore did not colonise the chicken intestinal tract after a single dose administration. Following challenge with Salmonella enterica serovar Enteritidis, the best protecting isolates increased the chicken's resistance to S. Enteritidis only tenfold, which, however, means that none of the tested individual bacterial isolates on their own efficiently protected chicks against S. Enteritidis.
- Klíčová slova
- Bacteroidetes, Firmicutes, Salmonella, caecum, chicken, colonisation, oral inoculation,
- Publikační typ
- časopisecké články MeSH
The gut microbiota of warm-blooded vertebrates consists of bacterial species belonging to two main phyla; Firmicutes and Bacteroidetes. However, does it mean that the same bacterial species are found in humans and chickens? Here we show that the ability to survive in an aerobic environment is central for host species adaptation. Known bacterial species commonly found in humans, pigs, chickens and Antarctic gentoo penguins are those capable of extended survival under aerobic conditions, i.e., either spore-forming, aerotolerant or facultatively anaerobic bacteria. Such bacteria are ubiquitously distributed in the environment, which acts as the source of infection with similar probability in humans, pigs, chickens, penguins and likely any other warm-blooded omnivorous hosts. On the other hand, gut anaerobes with no specific adaptation for survival in an aerobic environment exhibit host adaptation. This is associated with their vertical transmission from mothers to offspring and long-term colonisation after administration of a single dose. This knowledge influences the design of next-generation probiotics. The origin of aerotolerant or spore-forming probiotic strains may not be that important. On the other hand, if Bacteroidetes and other host-adapted species are used as future probiotics, host preference should be considered.
- Klíčová slova
- chicken, endospore, environment, gut microbiota, host adaptation, human, penguin, pig, spread,
- Publikační typ
- časopisecké články MeSH
Altogether 52 tissue samples and swabs from the corium of the claw of diseased cattle were investigated. Microbiological examinations revealed the presence of 11 strictly anaerobic bacterial strains that belonged to the species Peptococcus asacharolyticus, Pc. sacharolyticus, Peptostreptococcus anaerobius, Bacteroides asacharolyticus and B. melaninogenicus. The remaining isolates were classified as Bacteroides, Fusobacterium, Streptococcus and Clostridium. In the above-mentioned strains observations of their biochemical, morphological and enzymatic properties (Tab. I) were carried out. Their resistance to antibiotics was evaluated from the qualitative viewpoint (Tab. II). Capillary isotachophoresis was used to determine the amounts of volatile fatty acids that developed during glucose fermentation (Tab. III). In the single clinical samples the above-mentioned strains occurred as association of microorganism. The anaerobic genera Bacteroides and Fusobacterium were found in 52% of the samples (Bacteroides sp. and Fusobacterium sp. were recorded in 25% and 12% of the samples, respectively, whereas in 15% of the samples both species occurred). According to our results the etiology of dermatitis digitalis et interdigitalis is closely connected with the incidence of anaerobes. Of the latter, those belonging to the genera Bacteroides and Fusobacterium are of major importance.
Complex gut microbiota increases chickens' resistance to enteric pathogens. However, the principles of this phenomenon are not understood in detail. One of the possibilities for how to decipher the role of gut microbiota in chickens' resistance to enteric pathogens is to systematically characterise the gene expression of individual gut microbiota members colonising the chicken caecum. To reach this aim, newly hatched chicks were inoculated with bacterial species whose whole genomic sequence was known. Total protein purified from the chicken caecum was analysed by mass spectrometry, and the obtained spectra were searched against strain-specific protein databases generated from known genomic sequences. Campylobacter jejuni, Phascolarctobacterium sp. and Sutterella massiliensis did not utilise carbohydrates when colonising the chicken caecum. On the other hand, Bacteroides, Mediterranea, Marseilla, Megamonas, Megasphaera, Bifidobacterium, Blautia, Escherichia coli and Succinatimonas fermented carbohydrates. C. jejuni was the only motile bacterium, and Bacteroides mediterraneensis expressed the type VI secretion system. Classification of in vivo expression is key for understanding the role of individual species in complex microbial populations colonising the intestinal tract. Knowledge of the expression of motility, the type VI secretion system, and preference for carbohydrate or amino acid fermentation is important for the selection of bacteria for defined competitive exclusion products.
- Klíčová slova
- anaerobe, caecum, chicken microbiota, gene expression, mass spectrometry, metabolism,
- MeSH
- aminokyseliny MeSH
- anaerobní bakterie * metabolismus MeSH
- cékum mikrobiologie MeSH
- kur domácí * mikrobiologie MeSH
- metabolismus sacharidů MeSH
- sekreční systém typu IV MeSH
- střevní mikroflóra * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- aminokyseliny MeSH
- sekreční systém typu IV MeSH
Microbially induced corrosion (MIC), caused by iron-cycling microorganisms that directly uptake electrons from metallic iron, is a serious economic and environmental problem. Iron corrosion is inhibited at pH above 9.0 in the presence of carbonate by the formation of a passivating film, but the possibility of direct oxidation of metallic iron by anaerobic alkaliphiles has not been thoroughly investigated. This bioinduced process may pose a serious environmental hazard under anaerobic alkaline conditions of underground radioactive waste disposal in metal containers with bentonite clays. We used Geoalkalibacter ferrihydriticus, an anaerobic iron-cycling bacterium capable of both dissimilatory iron reduction and anaerobic iron oxidation, as a model organism to investigate the microbial ability to utilize Fe0 from steel wire as an electron donor under anaerobic autotrophic conditions at pH 9.5. During bacterial growth, corrosion of the steel wire was induced and accompanied by intense H2 production and precipitation of a solid phase. Mössbauer spectroscopy revealed that green rust with siderite admixture was the major mineral formed during Fe oxidation. Protons appeared to be the only thermodynamically favorable electron acceptor for G. ferrihydriticus. Their reduction could lead to hydrogen production. Genomic analysis supported the proposal of such a metabolic mode for the organism. Thus, we have shown that MIC can be realized under anaerobic alkaline conditions by iron-cycling microorganisms in the absence of organic substrates. Microbial hydrogen production may facilitate the further development of authigenic microflora, which could further increase corrosion in radioactive waste repositories and reduce the barrier properties of bentonite clays.IMPORTANCEMicrobially induced corrosion (MIC) is a problem with significant economic damage. MIC processes occurring under anaerobic conditions at neutral pH have been actively studied over the last decades. Meanwhile, MIC processes under anaerobic alkaline conditions remain very poorly understood, although they represent a serious environmental problem, as such conditions are characteristic of the geological disposal of nuclear waste stored in metal containers isolated by clays. Our studies of the corrosion of steel by the anaerobic iron-cycling bacterium Geoalkalibacter ferrihydriticus at pH 9.5 in the absence of any organic matter have shown that this process is possible and can be accompanied by the active release of hydrogen. The formation of this gas can trigger the development of an authigenic anaerobic microflora that uses it as an electron donor and can negatively affect the insulating properties of the clay barrier through microbial metabolic activity.
- Klíčová slova
- Geoalkalibacter ferrihydriticus, alkaline environments, direct Fe0-oxidation, iron-cycling anaerobes, microbially induced corrosion, protons reduction, steel,
- MeSH
- anaerobióza MeSH
- autotrofní procesy MeSH
- koncentrace vodíkových iontů MeSH
- koroze MeSH
- ocel * chemie MeSH
- oxidace-redukce MeSH
- železo * metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- ocel * MeSH
- železo * MeSH
