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, an oral pathobiont associated with colorectal cancer, epigenetically reprograms human colonocytes.Gut Microbes Dec 2023Recently, an intestinal dysbiotic microbiota with enrichment in oral cavity bacteria has been described in colorectal cancer (CRC) patients. Here, we characterize and...
Recently, an intestinal dysbiotic microbiota with enrichment in oral cavity bacteria has been described in colorectal cancer (CRC) patients. Here, we characterize and investigate one of these oral pathobionts, the Gram-positive anaerobic coccus . We identified two phylotypes (A and B) exhibiting different phenotypes and adhesion capabilities. We observed a strong association of phylotype A with CRC, with its higher abundance in feces and in tumoral tissue compared with the normal homologous colonic mucosa, which was associated with a distinct methylation status of patients. By developing an hypoxic co-culture system of human primary colonic cells with anaerobic bacteria, we show that phylotype A alters the DNA methylation profile promoters of key tumor-suppressor genes, oncogenes, and genes involved in epithelial-mesenchymal transition. In colonic mucosa of CRC patients carrying phylotype A, we found similar DNA methylation alterations, together with significant enrichment of differentially expressed genes in pathways involved in inflammation, cell adhesion, and regulation of actin cytoskeleton, providing evidence of possible role in the carcinogenic process.
Topics: Humans; Gastrointestinal Microbiome; Firmicutes; Bacteria; Colorectal Neoplasms
PubMed: 37842920
DOI: 10.1080/19490976.2023.2265138 -
MBio Aug 2023Polyphenols are abundant in nature, and their anaerobic biodegradation by gut and soil bacteria is a topic of great interest. The O requirement of phenol oxidases is...
Polyphenols are abundant in nature, and their anaerobic biodegradation by gut and soil bacteria is a topic of great interest. The O requirement of phenol oxidases is thought to explain the microbial inertness of phenolic compounds in anoxic environments, such as peatlands, termed the enzyme latch hypothesis. A caveat of this model is that certain phenols are known to be degraded by strict anaerobic bacteria, although the biochemical basis for this process is incompletely understood. Here, we report the discovery and characterization of a gene cluster in the environmental bacterium for the degradation phloroglucinol (1,3,5-trihydroxybenzene), a key intermediate in the anaerobic degradation of flavonoids and tannins, which constitute the most abundant polyphenols in nature. The gene cluster encodes the key C-C cleavage enzyme dihydrophloroglucinol cyclohydrolase, as well as ()-3-hydroxy-5-oxo-hexanoate dehydrogenase and triacetate acetoacetate-lyase, which enable phloroglucinol to be utilized as a carbon and energy source. Bioinformatics studies revealed the presence of this gene cluster in phylogenetically and metabolically diverse gut and environmental bacteria, with potential impacts on human health and carbon preservation in peat soils and other anaerobic environmental niches. IMPORTANCE This study provides novel insights into the microbiota's anaerobic metabolism of phloroglucinol, a critical intermediate in the degradation of polyphenols in plants. Elucidation of this anaerobic pathway reveals enzymatic mechanisms for the degradation of phloroglucinol into short-chain fatty acids and acetyl-CoA, which are used as a carbon and energy source for bacterium growth. Bioinformatics studies suggested the prevalence of this pathway in phylogenetically and metabolically diverse gut and environmental bacteria, with potential impacts on carbon preservation in peat soils and human gut health.
Topics: Humans; Phloroglucinol; Anaerobiosis; Bacteria; Bacteria, Anaerobic; Phenols; Polyphenols; Soil
PubMed: 37341492
DOI: 10.1128/mbio.01099-23 -
Environmental Science & Technology Nov 2023Peroxyacids (POAs) are a promising alternative to chlorine for reducing the formation of disinfection byproducts. However, their capacity for microbial inactivation and...
Peroxyacids (POAs) are a promising alternative to chlorine for reducing the formation of disinfection byproducts. However, their capacity for microbial inactivation and mechanisms of action require further investigation. We evaluated the efficacy of three POAs (performic acid (PFA), peracetic acid (PAA), and perpropionic acid (PPA)) and chlor(am)ine for inactivation of four representative microorganisms ( (Gram-negative bacteria), (Gram-positive bacteria), MS2 bacteriophage (nonenveloped virus), and Φ6 (enveloped virus)) and for reaction rates with biomolecules (amino acids and nucleotides). Bacterial inactivation efficacy (in anaerobic membrane bioreactor (AnMBR) effluent) followed the order of PFA > chlorine > PAA ≈ PPA. Fluorescence microscopic analysis indicated that free chlorine induced surface damage and cell lysis rapidly, whereas POAs led to intracellular oxidative stress through penetrating the intact cell membrane. However, POAs (50 μM) were less effective than chlorine at inactivating viruses, achieving only ∼1-log PFU removal for MS2 and Φ6 after 30 min of reaction in phosphate buffer without genome damage. Results suggest that POAs' unique interaction with bacteria and ineffective viral inactivation could be attributed to their selectivity toward cysteine and methionine through oxygen-transfer reactions and limited reactivity for other biomolecules. These mechanistic insights could inform the application of POAs in water and wastewater treatment.
Topics: Disinfectants; Virus Inactivation; Chlorine; Peracetic Acid; Disinfection; Bacteria; Water Purification
PubMed: 36995048
DOI: 10.1021/acs.est.2c09824 -
Therapeutics and Clinical Risk... 2023RFX, a rifamycin-based antibacterial agent obtained by the culture of the actinomycete Streptomyces mediterranei, has a broad antibacterial spectrum covering gram-... (Review)
Review
RFX, a rifamycin-based antibacterial agent obtained by the culture of the actinomycete Streptomyces mediterranei, has a broad antibacterial spectrum covering gram- positive, gram-negative, aerobic, and anaerobic bacteria. RFX is an antibiotic that elicits its effect by inhibiting bacterial RNA synthesis. When administered orally, its intestinal absorption is extremely low (<0.4%), restricting antibacterial activity mainly in the intestinal tract, with few systemic side effects. RFX has been recommended by the American Association for the Study of Liver Diseases and the European Association for the Study of the Liver guidelines for the treatment of HE. RFX may contribute to restore hepatic function and to decrease the development of liver fibrosis. Its efficacy has been shown in patients with previous hepatic encephalopathy and several complications, such as infections, including spontaneous bacterial peritonitis, ascites and oesophageal variceal bleeding. Thus, RFX has an outstanding role in the therapeutic arsenal in hepatic cirrhosis, under the concept of disease modifier.
PubMed: 37899985
DOI: 10.2147/TCRM.S425292 -
Journal of Medical Microbiology Mar 2024There is growing evidence that altered microbiota abundance of a range of specific anaerobic bacteria are associated with cancer, including spp., spp., spp., spp.,... (Review)
Review
There is growing evidence that altered microbiota abundance of a range of specific anaerobic bacteria are associated with cancer, including spp., spp., spp., spp., spp., spp spp and spp. linked to multiple cancer types. In this review we explore these pathogenic associations. The mechanisms by which bacteria are known or predicted to interact with human cells are reviewed and we present an overview of the interlinked mechanisms and hypotheses of how multiple intracellular anaerobic bacterial pathogens may act together to cause host cell and tissue microenvironment changes associated with carcinogenesis and cancer cell invasion. These include combined effects on changes in cell signalling, DNA damage, cellular metabolism and immune evasion. Strategies for early detection and eradication of anaerobic cancer-associated bacterial pathogens that may prevent cancer progression are proposed.
Topics: Humans; Bacteria, Anaerobic; Carcinogenesis; Immune Evasion; Porphyromonas; Signal Transduction; Tumor Microenvironment
PubMed: 38535967
DOI: 10.1099/jmm.0.001817 -
Sisli Etfal Hastanesi Tip Bulteni 2023Bloodstream infections (BSI) are associated with high morbidity and mortality. The aim of our study is to determine whether there is a relationship between certain risk...
OBJECTIVES
Bloodstream infections (BSI) are associated with high morbidity and mortality. The aim of our study is to determine whether there is a relationship between certain risk factors such as the underlying disease, patient's medical history, or interventional procedures and multidrug resistant (MDR) bacterial infection and to determine the risk factors for mortality.
METHODS
Two hundred and twenty-two outpatients and inpatients who were diagnosed with bacteremia over a 6-month period were included in the study. 232 agents from 222 patients were isolated and tested for antimicrobial susceptibility. The relationship between patients demographic and clinical data and MDR was analyzed.
RESULTS
The most common microorganisms were Gram-negative bacteria (59.4%), Gram-positive bacteria (36.9%), species (2.2%), and anaerobic bacteria (1.35%). The most common isolates were 53 (22.8%), 35 (%15.1), 26 (11.2%), spp. (n=17, 7.3%), spp 17 (7.3%), and spp 14 (6%). Microorganisms with the highest antimicrobial resistance observed were 82.3% in , 64.5% in coagulase-negative staphylococci, 60.3% in , 50% in , and 27.2% in spp. Most patients with BSI caused by MDR bacteria were in the intensive care unit (64%). Sepsis diagnosis, urinary catheter use, history of surgery, and use of broad-spectrum antibiotics as well as risk factors for antibiotic-resistant bacteremia, coronary artery disease, inappropriate empirical therapy, healthcare-associated infections, urinary catheterization, and stay in the ICU were determined as risk factors for mortality.
CONCLUSION
Our study identified the risk factors of BSI caused by MDR bacteria and helped to reveal the relationship between these factors and mortality.
PubMed: 37900327
DOI: 10.14744/SEMB.2023.31697 -
Frontiers in Microbiology 2024Previous studies have reported the role of some species of acidophilic bacteria in accelerating the dissolution of goethite under aerobic and anaerobic conditions. This...
Previous studies have reported the role of some species of acidophilic bacteria in accelerating the dissolution of goethite under aerobic and anaerobic conditions. This has relevance for environments impacted by acid mine drainage and for the potential bioleaching of limonitic laterite ores. In this study, natural well-characterized goethite mineral samples and synthetic goethite were used in aerobic and anaerobic laboratory batch culture incubation experiments with ferric iron-reducing, acidophilic bacteria, including the lithoautotrophic species , and , as well as two strains of the organoheterotrophic species . All bacteria remained alive throughout the experiments and efficiently reduced soluble ferric iron in solution in positive control assays. However, goethite dissolution was low to negligible in all experimental assays with natural goethite, while some dissolution occurred with synthetic goethite in agreement with previous publications. The results indicate that ferric iron-reducing microbial activity at low pH is less relevant for goethite dissolution than the oxidation of elemental sulfur to sulfuric acid. Microbial ferric iron reduction enhances but does not initiate goethite dissolution in very acidic liquors.
PubMed: 38846564
DOI: 10.3389/fmicb.2024.1360018 -
Biophysical Reviews Oct 2023The processes of microbiological destruction of toxic and large-tonnage waste are the most attractive processes for protecting the environment. The review considers the... (Review)
Review
The processes of microbiological destruction of toxic and large-tonnage waste are the most attractive processes for protecting the environment. The review considers the results of studies of microbial decomposition of nitrate esters, including hardly decomposable nitrocellulose. The published data show that specific microorganisms are able to degrade nitrated cellulose compounds under both anaerobic and aerobic conditions. The most promising microorganisms in terms of the efficiency of the nitrocellulose degradation process are bacteria belonging to genera, fungi and , as well as their co-cultivation. Recently, the first information about the enzymes involved in the process of nitrocellulose degradation, possible mechanisms of reactions carried out by these enzymes, and the effect of electron donors and acceptors adding to the process have been obtained. Contamination of industrial wastewater with nitrocellulose leads to treatment necessity by using cost-effective, harmless methods. A combined aerobic-anaerobic system, including both bacteria and fungi, has shown hopeful results.
PubMed: 37974989
DOI: 10.1007/s12551-023-01159-1