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1.
Methods Mol Biol ; 2839: 113-130, 2024.
Article in English | MEDLINE | ID: mdl-39008251

ABSTRACT

Traditional studies of cellular metabolism have relied on the use of radioisotopes. These have clear disadvantages associated with safety and waste generation. Furthermore, detection of the labeled species by scintillation counting provides only a quantification of its presence or absence. The use of stable isotopes, by contrast, allows the application of powerful, orthogonal spectroscopic approaches such as nuclear magnetic resonance spectroscopy (NMR) and various mass spectrometric methods. Using stable isotope labeling to study heme metabolism requires integrating methods for (a) generating the heme in labeled forms, (b) cultivating and quantifying the organism of choice in chemically defined media, to which labeled compounds can be added, (c) recovering cellular components and/or spent growth media, and (d) analyzing these materials for the labeled species using spectroscopic and mass spectrometric methods. These methods are summarized here in the context of Bacteroides thetaiotaomicron, a generally nonpathogenic anaerobe and heme auxotroph.


Subject(s)
Bacteroides thetaiotaomicron , Heme , Mass Spectrometry , Heme/metabolism , Mass Spectrometry/methods , Bacteroides thetaiotaomicron/metabolism , Bacteroides thetaiotaomicron/growth & development , Magnetic Resonance Spectroscopy/methods , Isotope Labeling/methods , Culture Media/chemistry
2.
BMC Infect Dis ; 24(1): 677, 2024 Jul 08.
Article in English | MEDLINE | ID: mdl-38977947

ABSTRACT

BACKGROUND: Hoylesella marshii can be isolated from human oral cavities affected by dental pulp and periodontal infections, as well as from the dental plaque of healthy individuals, making it a common bacterium within the oral microbiota. However, its role in causing pleural infections in humans is rare. CASE PRESENTATION: A case of purulent pleural effusion occurred shortly after discharge in an elderly patient who had undergone surgery for gastric cancer. The infection was identified as being caused by an obligate anaerobe through laboratory culture, and was further identified as Hoylesella marshii causing pleural infection through 16 S rRNA gene sequence analysis. Susceptibility testing guided precise treatment with cefoperazone-sulbactam and metronidazole. The patient's clinical symptoms improved rapidly, laboratory test indicators gradually returned to normal, and the patient ultimately recovered. CONCLUSION: Hoylesella marshii can cause pleural infections in humans. Clinical microbiology laboratories should pay special attention to the cultivation of obligate anaerobes when routine aerobic cultures do not show bacterial growth but bacteria are visible on smear staining, and when conventional identification methods fail to identify the bacterium, analysis based on the highly conserved 16 S rRNA gene sequence can accurately and specifically identify the bacterium, guiding clinicians in formulating precise anti-infection strategies.


Subject(s)
Anti-Bacterial Agents , RNA, Ribosomal, 16S , Humans , RNA, Ribosomal, 16S/genetics , Anti-Bacterial Agents/therapeutic use , Male , Aged , Pleural Effusion/microbiology , Microbial Sensitivity Tests , Metronidazole/therapeutic use , Pleural Diseases/microbiology , Pleural Diseases/diagnosis
3.
Article in English | MEDLINE | ID: mdl-38967634

ABSTRACT

An anaerobic, mesophilic, syntrophic, archaeon strain MK-D1T, was isolated as a pure co-culture with Methanogenium sp. strain MK-MG from deep-sea methane seep sediment. This organism is, to our knowledge, the first cultured representative of 'Asgard' archaea, an archaeal group closely related to eukaryotes. Here, we describe the detailed physiology and phylogeny of MK-D1T and propose Promethearchaeum syntrophicum gen. nov., sp. nov. to accommodate this strain. Cells were non-motile, small cocci, approximately 300-750 nm in diameter and produced membrane vesicles, chains of blebs and membrane-based protrusions. MK-D1T grew at 4-30 °C with optimum growth at 20 °C. The strain grew chemoorganotrophically with amino acids, peptides and yeast extract with obligate dependence on syntrophy with H2-/formate-utilizing organisms. MK-D1T showed the fastest growth and highest maximum cell yield when grown with yeast extract as the substrate: approximately 3 months to full growth, reaching up to 6.7×106 16S rRNA gene copies ml-1. MK-D1T had a circular 4.32 Mb chromosome with a DNA G+C content of 31.1 mol%. The results of phylogenetic analyses of the 16S rRNA gene and conserved marker proteins indicated that the strain is affiliated with 'Asgard' archaea and more specifically DHVC1/DSAG/MBG-B and 'Lokiarchaeota'/'Lokiarchaeia'. On the basis of the results of 16S rRNA gene sequence analysis, the most closely related isolated relatives were Infirmifilum lucidum 3507LTT (76.09 %) and Methanothermobacter tenebrarum RMAST (77.45 %) and the closest relative in enrichment culture was Candidatus 'Lokiarchaeum ossiferum' (95.39 %). The type strain of the type species is MK-D1T (JCM 39240T and JAMSTEC no. 115508). We propose the associated family, order, class, phylum, and kingdom as Promethearchaeaceae fam. nov., Promethearchaeales ord. nov., Promethearchaeia class. nov., Promethearchaeota phyl. nov., and Promethearchaeati regn. nov., respectively. These are in accordance with ICNP Rules 8 and 22 for nomenclature, Rule 30(3)(b) for validation and maintenance of the type strain, and Rule 31a for description as a member of an unambiguous syntrophic association.


Subject(s)
Base Composition , DNA, Archaeal , Phylogeny , RNA, Ribosomal, 16S , Sequence Analysis, DNA , RNA, Ribosomal, 16S/genetics , DNA, Archaeal/genetics , Geologic Sediments/microbiology , Anaerobiosis , Seawater/microbiology , Vitamin K 2/analogs & derivatives
4.
Biotechnol Bioeng ; 2024 Jul 02.
Article in English | MEDLINE | ID: mdl-38956879

ABSTRACT

Acetogenic Clostridia are obligate anaerobes that have emerged as promising microbes for the renewable production of biochemicals owing to their ability to efficiently metabolize sustainable single-carbon feedstocks. Additionally, Clostridia are increasingly recognized for their biosynthetic potential, with recent discoveries of diverse secondary metabolites ranging from antibiotics to pigments to modulators of the human gut microbiota. Lack of efficient methods for genomic integration and expression of large heterologous DNA constructs remains a major challenge in studying biosynthesis in Clostridia and using them for metabolic engineering applications. To overcome this problem, we harnessed chassis-independent recombinase-assisted genome engineering (CRAGE) to develop a workflow for facile integration of large gene clusters (>10 kb) into the human gut acetogen Eubacterium limosum. We then integrated a non-ribosomal peptide synthetase gene cluster from the gut anaerobe Clostridium leptum, which previously produced no detectable product in traditional heterologous hosts. Chromosomal expression in E. limosum without further optimization led to production of phevalin at 2.4 mg/L. These results further expand the molecular toolkit for a highly tractable member of the Clostridia, paving the way for sophisticated pathway engineering efforts, and highlighting the potential of E. limosum as a Clostridial chassis for exploration of anaerobic natural product biosynthesis.

5.
Syst Appl Microbiol ; 47(5): 126528, 2024 Jun 28.
Article in English | MEDLINE | ID: mdl-38959749

ABSTRACT

A novel facultatively anaerobic moderately thermophilic bacteria, strains 4137-MeT and 4148-MeT, were isolated from hot springs of Karmadon and Ursdon, respectively (North Ossetia, Russian Federation). Gram-negative, motile rods were present singly, in pairs, rosettes, and aggregates, or formed biofilms. Both strains grew optimally at 50-55 °C, pH 7.0 and did not require sodium chloride or yeast extract for growth. They were chemoorganoheterotrophs, growing on mono-, di- and polysaccharides (cellulose, starch, xylan, lichenan, galactan, xyloglucan, mannan, xanthan gum, guar gum) as well as proteinaceous substrates (gelatin, peptone, beef and yeast extract). Growth under anaerobic conditions was observed in presence and absence of external electron acceptors. Sulfur, thiosulfate, arsenate, Fe-citrate, and ferrihydrite were reduced with acetate, starch, or yeast extract as electron donors. The respiratory quinone was MK-7. Major cellular fatty acids of both strains were iso-C15:0, anteiso-C17:0, C15:0, iso-C16:0 and additionally iso-C17:0 for strain 4137-MeT. The size of the genome and genomic DNA G + C content of strain 4137-MeT were 3.24 Mb. and 29.9 %, respectively; for strain 4148-MeT - 3.33 Mb and 30.7 %. According to the 16S rRNA gene sequence and conserved protein sequences phylogenies, strains 4137-MeT and 4148-MeT represented a distinct lineage of the family Melioribacteraceae within the class Ignavibacteria. Based on phylogenetic analysis and phenotypic features, the novel isolates were assigned to a novel genus, for which the name Rosettibacter gen. nov. is proposed. Strain 4148-MeT represents its type species Rosettibacter primus sp. nov., while strain 4137-MeT represents a new species Rosettibacter firmus sp. nov.

6.
EBioMedicine ; 105: 105216, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38924841

ABSTRACT

BACKGROUND: This study aimed to characterise the infant penile (coronal sulcus) microbiome and the effects of early infant male circumcision (EIMC), following a standard surgical method (Mogen Clamp) and a non-surgical alternative (ShangRing). METHODS: We collected coronal sulcus swabs at baseline and on days 7 and 14 post-circumcision from infants assigned to receive EIMC by Mogen Clamp (n = 15) or ShangRing (n = 15), in a randomised trial in Rakai and Kakuuto, Uganda. We used 16S rRNA gene-based sequencing and broad-coverage qPCR to characterise the infant penile microbiome and assess the effects of EIMC in both study arms. FINDINGS: Prior to EIMC, the infant penile microbiome had a mixture of facultative and strict anaerobes. In both study arms, EIMC caused penile microbiome proportional abundance changes characterised by decreases in penile anaerobes [ShangRing Prevotella: -15.0%, (SD = 19.1); Mogen clamp Prevotella: -3.6% (11.2); ShangRing Veillonella: -11.3% (17.2); Mogen clamp Veillonella: -2.6% (11.8)] and increases in skin-associated facultative anaerobes [ShangRing Corynebacterium: 24.9%, (22.4); Mogen clamp Corynebacterium: 4.7% (21.3); ShangRing Staphylococcus: 21.1% (20.5); Mogen clamp Staphylococcus: 18.1% (20.1)]. Clostridium tetani was not detected during the study. INTERPRETATION: Mogen Clamp and ShangRing EIMC both changed the composition of the infant penile microbiome by reducing the proportional abundances of anaerobes and uropathogens, which is consistent with medical male circumcision findings in adults. C. tetani was not increased by either EIMC method. FUNDING: Bill and Melinda Gates Foundation.


Subject(s)
Circumcision, Male , Microbiota , Penis , RNA, Ribosomal, 16S , Humans , Male , Penis/microbiology , Infant , RNA, Ribosomal, 16S/genetics , Infant, Newborn , Uganda , Bacteria/genetics , Bacteria/classification , Bacteria/isolation & purification
7.
J Infect Chemother ; 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38825001

ABSTRACT

We present a case of tubo-ovarian abscess (TOA) caused by Clostridioides difficile (CD) in a 43-year-old female. Despite lacking a history of sexually transmitted diseases, the patient had undergone paraovarian cystectomy nine months before admission. Transvaginal ultrasonography performed eight months post-surgery revealed left ovarian enlargement, accompanied by subsequent lower abdominal pain and fever exceeding 38 °C. As oral antibiotic treatment was ineffective, the patient was admitted to our hospital. Computed tomography upon admission revealed a massive TOA. Surgical drainage of the abscess was performed, and CD was identified in the culture from the pus. The TOA was treated with a three-month course of metronidazole and oral amoxicillin/clavulanic acid. While CD is commonly associated with colitis, extraintestinal manifestations are exceptionally rare. This case represents the inaugural report of TOA resulting from CD. A literature review on abdominal and pelvic CD abscesses found that patients undergoing surgical drainage had a favorable prognosis. Therefore, surgical intervention plays an important role in the management of CD abscesses.

8.
Int J Mol Sci ; 25(12)2024 Jun 13.
Article in English | MEDLINE | ID: mdl-38928209

ABSTRACT

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.


Subject(s)
Amino Acids , Chickens , Gastrointestinal Microbiome , Type VI Secretion Systems , Animals , Chickens/microbiology , Amino Acids/metabolism , Type VI Secretion Systems/metabolism , Type VI Secretion Systems/genetics , Carbohydrate Metabolism , Cecum/microbiology , Cecum/metabolism , Bacteria/classification , Bacteria/metabolism , Bacteria/genetics
9.
Food Res Int ; 190: 114610, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38945575

ABSTRACT

Spore-forming bacteria are the most complex group of microbes to eliminate from the dairy production line due to their ability to withstand heat treatment usually used in dairy processing. These ubiquitous microorganisms have ample opportunity for multiple points of entry into the milk chain, creating issues for food quality and safety. Certain spore-formers, namely bacilli and clostridia, are more problematic to the dairy industry due to their possible pathogenicity, growth, and production of metabolites and spoilage enzymes. This research investigated the spore-forming population from raw milk reception at two Norwegian dairy plants through the cheesemaking stages until ripening. Samples were collected over two years and examined by amplicon sequencing in a culture independent manner and after an anaerobic spore-former enrichment step. In addition, a total of 608 isolates from the enriched samples were identified at the genus or species level using MALDI-TOF analysis. Most spore-forming isolates belong to the genera Bacillus or Clostridium, with the latter dominating the enriched MPN tubes of raw milk and bactofugate. Results showed a great variation among the clostridia and bacilli detected in the enriched MPN tubes. However, B. licheniformis and C. tyrobutyricum were identified in all sample types from both plants throughout the 2-year study. In conclusion, our results shed light on the fate of different spore-formers at different processing stages in the cheese production chain, which could facilitate targeted actions to reduce quality problems.


Subject(s)
Cheese , Food Microbiology , Spores, Bacterial , Norway , Cheese/microbiology , Spores, Bacterial/isolation & purification , Milk/microbiology , Clostridium/isolation & purification , Clostridium/genetics , Animals , Bacillus/isolation & purification , Bacillus/genetics , Bacillus/classification , Food Handling/methods , Dairying
10.
Front Oral Health ; 5: 1348946, 2024.
Article in English | MEDLINE | ID: mdl-38774039

ABSTRACT

This review explores the results of research on oral health concerning cardiovascular diseases and some forms of cancer and is based on results from published systematic reviews and some studies. The research results will have a strong focus on exploring the relationship between different aspects of oral infections. The relationship between oral health parameters, cardiovascular diseases (CVD), and certain cancers was examined from different angles, including prospective analyses, in a population-based health study in Oslo from the year 2000 (Oslo II study). A major finding was that low levels of antibodies to the oral anaerobe Tannerella forsythia predict both CVD mortality in men with a history of myocardial infarction and incidence of bladder cancer in a random sample of men in the study. Low levels of antibodies to Treponea denticola predict the incidence of bladder and colon cancer in a random sample of men in the study. Both anaerobe bacteria are part of the so-called red complex of bacteria in chronic periodontitis together with Pophyromonas gingivalis. These three bacteria have different properties and are causal in chronic periodontitis. They migrate into the local tissues by adhering to the oral epithelium, break down soft and hard tissues, and spread via the circulation to organs distant from the mouth. This paper will give an overview of which oral health measures have been explored and associated with different CVD and cancer diagnoses and what scientific literature supports or contravenes our hypothesis. The oral microbiome is described with the most relevant bacteria related to microbiology, serum, autopsies, and associated causes such as alcohol. There will be a mention of the possibilities and limitations of different study designs. There seems to be a causal relationship between oral anaerobe bacteria and systemic diseases regulated by the immune system. This is seen alongside other well-known risk factors, especially for CVD. The prospective finding of a relation to the incidence of certain cancers and CVD is particularly intriguing. However, further research is needed to determine the biological mechanisms underpinning these associations.

11.
Life (Basel) ; 14(5)2024 Apr 26.
Article in English | MEDLINE | ID: mdl-38792585

ABSTRACT

A novel aerotolerant anaerobic bacterium (strain M4AhT) was isolated from a terrestrial mud volcano (Taman Peninsula, Russia). Cells were small, cell-wall-less, non-motile cocci, 0.32-0.65 µm in diameter. The isolate was a mesophilic, neutrophilic chemoorganoheterotroph, growing on carbohydrates (D-glucose, D-trehalose, D-ribose, D-mannose, D-xylose, D-maltose, D-lactose, D-cellobiose, D-galactose, D-fructose, and D-sucrose), proteinaceous compounds (yeast extract, tryptone), and pyruvate. Strain M4AhT tolerated 2% oxygen in the gas phase, was catalase-positive, and showed sustainable growth under microaerobic conditions. The dominant cellular fatty acids of strain M4AhT were C16:0 and C18:0. The G+C content of the genomic DNA was 32.42%. The closest phylogenetic relative of strain M4AhT was Mariniplasma anaerobium from the family Acholeplasmataceae (order Acholeplasmatales, class Mollicutes). Based on the polyphasic characterization of the isolate, strain M4AhT is considered to represent a novel species of a new genus, for which the name Peloplasma aerotolerans gen. nov., sp. nov. is proposed. The type strain of Peloplasma aerotolerans is M4AhT (=DSM 112561T = VKM B-3485T = UQM 41475T). This is the first representative of the order Acholeplasmatales, isolated from a mud volcano.

12.
Syst Appl Microbiol ; 47(4): 126515, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38776610

ABSTRACT

A novel anaerobic, thermophilic bacterium of the class Atribacteria, strain M15T, was isolated from a high-temperature gas reservoir, Japan. Cells of strain M15T were gram-negative, short oval-shaped, and lacked flagella. Growth occurred at 45-75 °C (optimum 70-75 °C) and pH 6.5-8.5 (optimum pH 7.5-8.0) and was fast under optimal conditions (doubling time 11.4 h). Yeast extract was required for growth. Fermentative growth with glucose, arabinose, xylose, and cellobiose was observed. The major fermentative end products of glucose were acetate and hydrogen. The major cellular fatty acids were C16:0, iso-C15:0, and C18:0. The genomic G + C content was 46.0 mol%. Fluorescence and electron microscopy observations revealed the intracellular localization of genomic DNA surrounded by a membrane in the cells of strain M15T as reported in a sole validly described species of the class Atribacteria in the phylum Atribacterota, Atribacter laminatus strain RT761T, suggesting that the unique morphological traits are widely shared in this class. Phylogenetic analyses indicated that strain M15T belongs to a distinct family-level lineage in the class Atribacteria and shows low similarities to Atribacter laminatus strain RT761T (16S rRNA gene sequence identity of 90.1 %, average nucleotide identity [ANI] of 66.1 %, average amino acid identity [AAI] of 55.8 %). Phenotypic traits of strain M15T (thermophilic, fast-growing, relatively high G + C content, etc.) were clearly distinct from A. laminatus. Based on these phenotypic and genomic properties, we propose a novel genus and species, Atrimonas thermophila gen. nov., sp. nov. for strain M15T (=JCM39389T, =KCTC25731T) representing a novel family Atrimonadaceae fam., nov. in the class Atribacteria.


Subject(s)
Bacterial Typing Techniques , Base Composition , DNA, Bacterial , Fatty Acids , Phylogeny , RNA, Ribosomal, 16S , Sequence Analysis, DNA , RNA, Ribosomal, 16S/genetics , Fatty Acids/analysis , DNA, Bacterial/genetics , Japan , Hot Temperature , Fermentation , Oil and Gas Fields/microbiology
13.
Eur J Protistol ; 94: 126087, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38761673

ABSTRACT

Ciliates of the class Plagiopylea play a vital role in various anaerobic environments as consumers of prokaryotes. Yet, the diversity and phylogeny of this group of ciliates, especially marine representatives, remain poorly known. In this study, three Parasonderia species, viz., Parasonderia elongata spec. nov., and the already known P. cyclostoma and P. vestita, discovered in anaerobic sediments from various intertidal zones in China, were investigated based on their living morphology, infraciliature, and small subunit ribosomal rRNA gene sequences. Parasonderia elongata can be recognized by its larger body size, elongated body shape, oval oral opening, number of oral kineties, and significantly shortened leftmost postbuccal polykineties on the cell surface. Improved diagnosis and redescription of P. cyclostoma is provided for the first time, including data on infraciliature and molecular sequence. Phylogenetic analyses revealed that the three species cluster together and with the sequence of a Chinese population of P. vestita already present in the GenBank database, forming a robust clade.


Subject(s)
Ciliophora , Phylogeny , Species Specificity , Ciliophora/classification , Ciliophora/genetics , Ciliophora/cytology , China , RNA, Ribosomal, 18S/genetics , Geologic Sediments/parasitology
14.
Indian J Med Microbiol ; 49: 100595, 2024.
Article in English | MEDLINE | ID: mdl-38641008

ABSTRACT

Paeniclostridium sordellii, an anaerobic bacterium, causes hepatic infections in alcoholics and post-surgery (liver transplantation). While liver and brain abscesses are rare, drainage procedures and targeted antibiotic therapy assisted by early microbiological diagnosis have reduced mortality rates. We report a rare case of pyogenic liver abscess caused by Paeniclostridium sordellii in India, the early diagnosis of which has led to life saving outcome for the patient. Hence, the microbiological diagnosis and comprehensive medical-surgical treatment are vital for preventing mortality in Paeniclostridium sordellii infections.


Subject(s)
Anti-Bacterial Agents , Humans , India , Male , Anti-Bacterial Agents/therapeutic use , Liver Abscess, Pyogenic/microbiology , Liver Abscess, Pyogenic/diagnosis , Liver Abscess, Pyogenic/drug therapy , Treatment Outcome , Liver Abscess/microbiology , Middle Aged
15.
Microbiol Resour Announc ; 13(3): e0125923, 2024 Mar 12.
Article in English | MEDLINE | ID: mdl-38376195

ABSTRACT

Parabacteroides distasonis is an anaerobic bacterium with ambivalent health effects. P. distasonis strain GP102 was isolated from the cecum content of a morbid pregnant laboratory guinea pig (Cavia porcellus). The genome consists of one circular 5.39-Mbp chromosome with a G + C content of 44.79%.

16.
Eur J Protistol ; 93: 126052, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38302295

ABSTRACT

Psalteriomonadidae are a small family of anaerobic free-living protists belonging to Heterolobosea, Discoba. We cultured 74 new strains of mostly amoeboid Psalteriomonadidae obtained from mainly freshwater habitats and sequenced their 18S rRNA gene. Based on the phylogenetic analysis and genetic distances, we report multiple novel species, four of which we formally describe based on the light-microscopic morphology (Psalteriomonas minuta, P. australis, P. fimbriata, and P. parva). We also examined the ultrastructure of two Psalteriomonas species using transmission electron microscopy. We transfer Sawyeria marylandensis into the genus Psalteriomonas and synonymize Sawyeria with Psalteriomonas. In addition, we studied the flagellate stage of P. marylandensis comb. nov. for the first time, using light and scanning electron microscopy.


Subject(s)
Eukaryota , Lighting , Phylogeny , RNA, Ribosomal, 18S/genetics , Microscopy, Electron, Transmission , Sequence Analysis, DNA
17.
Mol Ecol ; 33(1): e16862, 2024 Jan.
Article in English | MEDLINE | ID: mdl-36786039

ABSTRACT

Different host species associate with distinct gut microbes in mammals, a pattern sometimes referred to as phylosymbiosis. However, the processes shaping this host specificity are not well understood. One model proposes that barriers to microbial transmission promote specificity by limiting microbial dispersal between hosts. This model predicts that specificity levels measured across microbes is correlated to transmission mode (vertical vs. horizontal) and individual dispersal traits. Here, we leverage two large publicly available gut microbiota data sets (1490 samples from 195 host species) to test this prediction. We found that host specificity varies widely across bacteria (i.e., there are generalist and specialist bacteria) and depends on transmission mode and dispersal ability. Horizontally-like transmitted bacteria equipped with traits that facilitate switches between host (e.g., tolerance to oxygen) were found to be less specific (more generalist) than microbes without those traits, for example, vertically-like inherited bacteria that are intolerant to oxygen. Altogether, our findings are compatible with a model in which limited microbial dispersal abilities foster host specificity.


Subject(s)
Gastrointestinal Microbiome , Animals , Mammals/microbiology , Host Specificity , Bacteria/genetics , Oxygen
19.
FEBS J ; 291(3): 596-608, 2024 02.
Article in English | MEDLINE | ID: mdl-37885325

ABSTRACT

Acetogenic bacteria such as the thermophilic anaerobic model organism Moorella thermoacetica reduce CO2 with H2 as a reductant via the Wood-Ljungdahl pathway (WLP). The enzymes of the WLP of M. thermoacetica require NADH, NADPH, and reduced ferredoxin as reductants. Whereas an electron-bifurcating ferredoxin- and NAD+ -reducing hydrogenase HydABC had been described, the enzyme that reduces NADP+ remained to be identified. A likely candidate is the HydABCDEF hydrogenase from M. thermoacetica. Genes encoding for the HydABCDEF hydrogenase are expressed during growth on glucose and dimethyl sulfoxide (DMSO), an alternative electron acceptor in M. thermoacetica, whereas expression of the genes hydABC encoding for the electron-bifurcating hydrogenase is downregulated. Therefore, we have purified the hydrogenase from cells grown on glucose and DMSO to apparent homogeneity. The enzyme had six subunits encoded by hydABCDEF and contained 58 mol of iron and 1 mol of FMN. The enzyme reduced methyl viologen with H2 as reductant and of the physiological acceptors tested, only NADP+ was reduced. Electron bifurcation with pyridine nucleotides and ferredoxin was not observed. H2 -dependent NADP+ reduction was optimal at pH 8 and 60 °C; the specific activity was 8.5 U·mg-1 and the Km for NADP+ was 0.086 mm. Cell suspensions catalyzed H2 -dependent DMSO reduction, which is in line with the hypothesis that the NADP+ -reducing hydrogenase HydABCDEF is involved in electron transfer from H2 to DMSO.


Subject(s)
Hydrogenase , Moorella , Hydrogenase/genetics , Ferredoxins/metabolism , NADP/metabolism , Bacterial Proteins/metabolism , Reducing Agents , Dimethyl Sulfoxide , Glucose/metabolism
20.
Biotechnol Bioeng ; 121(1): 219-227, 2024 01.
Article in English | MEDLINE | ID: mdl-37807712

ABSTRACT

Methods for culturing oxygen-sensitive cells and organisms under anaerobic conditions are vital to biotechnology research. Here, we report a biomaterial-based platform for anaerobic culture that consists of glucose oxidase (GOX) functionalized alginate microparticles (ALG-GOX), which are designed to deplete dissolved [O2 ] through enzymatic activity. ALG-GOX microparticles were synthesized via a water-in-oil emulsion and had a size of 132.0 ± 51.4 µm. Despite having a low storage modulus, the microparticles remained stable under aqueous conditions due to covalent crosslinking through amide bonds. Enzyme activity was tunable based on the loaded GOX concentration, with a maximum activity of 3.6 ± 0.3 units/mg of microparticles being achieved at an initial loading concentration of 5 mg/mL of GOX in alginate precursor solution. High enzyme activity in ALG-GOX microparticles resulted in rapid oxygen depletion, producing a suitable environment for anaerobic culture. Microparticles loaded with both GOX and catalase (ALG-GOX-CAT) to reduce H2 O2 buildup exhibited sustained activity for potential long-term anaerobic culture. ALG-GOX-CAT microparticles were highly effective for the anaerobic culture of Bacteroides thetaiotaomicron, with 10 mg/mL of ALG-GOX-CAT microparticles supporting the same level of growth in an aerobic environment compared to an anaerobic chamber after 16 h (8.70 ± 0.96 and 10.03 ± 1.03 million CFU, respectively; N.S. p = 0.07). These microparticles could be a valuable tool for research and development in biotechnology.


Subject(s)
Alginates , Cell Culture Techniques , Alginates/chemistry , Anaerobiosis , Glucose Oxidase/chemistry
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