Facultative Anaerobic Bacteria Research Articles

Case report: Relaps of Streptococcus suis infection in patient with Meningoencephalitis at Prof. Ngoerah Hospital, Bali

Background: S. suis is a facultative anaerobic Gram-positive bacterium that causes human infection. It is a primary health problem in the swine industry. Ceftriaxone is a therapeutic option for meningitis besides Ampicillin. Recently, the incidence of resistance to ceftriaxone was reported. The recurrence of S. suis in this patient is thought to be caused by ceftriaxone resistance due to inadequate initial therapy. Case Presentation: A 43-year-old male patient came to the ER with headaches in the head and neck. The patient had a history of meningitis due to S. suis twice before. While in the ER, the patient was given ceftriaxone while awaiting culture results. Blood cultures showed S. suis infection using VITEK 2 COMPACT (Biomeriuex®) and ceftriaxone resistance. The patient was successfully managed with Ampicillin following these culture results, leading to good outcomes. Discussion: S. suis is a gram-positive bacterial pathogen in pigs that can cause severe human infection, including meningitis, septicemia, endocarditis and deafness the most common complications. The patient experienced three relapses due to S. suis. On the third visit, blood culture results identified ceftriaxone-resistant S. suis. The patient's recurrent relapses could be attributed to several factors, including inadequate antibiotic administration, antibiotic resistance, weak immune system, contact with the source of infection and environmental variables, highlighting the complexity and challenges in treating S. suis infection. Conclusion: The use of antibiotics in relapse cases has the potential to cause antibiotic resistance, so it’s necessary to make guidelines for antibiotic therapy in S. suis infection to prevent recurrent infections.

Characteristics and in vitro properties of potential probiotic strain Fructobacillus tropaeoli KKP 3032 isolated from orange juice.

Fructobacillus, a Gram-positive, non-spore-forming, facultative anaerobic bacterium, belongs to the fructophilic lactic acid bacteria (FLAB) group. The group's name originates from fructose, the favored carbon source for its members. Fructobacillus spp. are noteworthy for their distinctive traits, captivating the interest of scientists. However, there have been relatively few publications regarding the isolation and potential utilization of these microorganisms in the industry. In recent years, F. tropaeoli has garnered interest for its promising role in the food and pharmaceutical sectors, although the availability of isolates is rather limited. A more comprehensive understanding of Fructobacillus is imperative to evaluate their functionality in the industry, given their unique and exceptional properties. Our in vitro study on Fructobacillus tropaeoli KKP 3032 confirmed its fructophilic nature and high osmotolerance. This strain thrives in a 30% sugar concentration, shows resistance to low pH and bile salts, and exhibits robust autoaggregation. Additionally, it displays significant antimicrobial activity against foodborne pathogens. Evaluating its probiotic potential, it aligns with EFSA recommendations in antibiotic resistance, except for kanamycin, to which it is resistant. Further research is necessary, but preliminary analyses confirm the high probiotic potential of F. tropaeoli KKP 3032 and its ability to thrive in the presence of high concentrations of fructose. The results indicate that the isolate F. tropaeoli KKP 3032 could potentially be used in the future as a fructophilic probiotic, protective culture, and/or active ingredient in fructose-rich food.

Structural and Functional Insight Into YefM-YoeB Complex of Toxin-Antitoxin System From Streptococcus pneumoniae.

Streptococcus pneumonia is a Gram-positive and facultative anaerobic bacterium that causes a number of diseases, including otitis media, community-acquired pneumonia, sepsis, and meningitis. With the emergence of antibiotic-resistant strains, there is an urgent need to develop antibiotics with a novel mechanism. The toxin-antitoxin (TA) system, which is primarily found in prokaryotes, consists of a toxin and its equivalent antitoxin genes. The YefM-YoeB module is a Type II TA system, where the YoeB toxin functions as a putative mRNA interferase upon activation, while the YefM antitoxin acts as a transcription repressor by binding to its promoter region along with YoeB. In this study, we determined the crystal structure of the YefM-YoeB complex from S. pneumoniae TIGR4 to comprehend the binding mechanism of the TA system. Furthermore, an in vitro ribonuclease activity assay was conducted to identify the ribonuclease activity of the YoeB toxin. Additionally, furthermore, the oligomeric state of the YefM-YoeB complex in solution was investigated, and a DNA-binding mode was proposed. These structural and functional insights into the YefM-YoeB complex could provide valuable information for the development of novel antibiotics targeting S. pneumonia-associated diseases.

Study of Bacillus cereus as an Effective Multi-Type A Trichothecene Inactivator

Type A trichothecenes are common mycotoxins in stored cereal grains, where co-contamination is likely to occur. Seeking new microbiological options capable of inactivating more than one type A trichothecene, this study aimed to analyze facultative anaerobe bacteria isolated from broiler proventriculus. For this purpose, type A trichothecenes were produced in vitro, and a facultative anaerobic bacterial consortium was obtained from a broiler’s proventriculus. Then, the most representative bacterial strains were purified, and trichothecene inactivating assays were performed. Finally, the isolate with the greatest capacity to remove all tested mycotoxins was selected for biosorption assays. The results showed that when the consortium was tested, neosolaniol (NEO) was the most degraded mycotoxin (64.55%; p = 0.008), followed by HT-2 toxin (HT-2) (22.96%; p = 0.008), and T-2 toxin (T-2) (20.84%; p = 0.014). All isolates were bacillus-shaped and Gram-positive, belonging to the Bacillus and Lactobacillus genera, of which B. cereus was found to remove T-2 (28.35%), HT-2 (32.84%), and NEO (27.14%), where biosorption accounted for 86.10% in T-2, 35.59% in HT-2, and 68.64% in NEO. This study is the first to prove the capacity of B. cereus as an effective inactivator and binder of multi-type A trichothecenes.

Facultative anaerobic bacteria enable syntrophic fatty acids degradation under micro-aerobic conditions.

Trace amounts of oxygen stimulate facultative anaerobic bacteria (FAB) within anaerobic bioreactors, which was shown to correlate with enhanced methane production from long-chain fatty acids. The relationship between FAB and fatty acid-degrading syntrophic communities under micro-aerobic conditions is still not clear. In this work, two syntrophic co-cultures, Syntrophomonas wolfei + Methanospirillum hungatei and Syntrophomonas zehnderi + Methanobacterium formicicum, were assembled and incubated with short, medium and long-chain fatty acids, with 0-10 % O2, in the presence and absence of FAB, here represented by Pseudomonas spp. Without Pseudomonas, the syntrophic activity was inhibited by 79 % at 0.5 %O2, but with Pseudomonas, the syntrophic co-cultures successfully converted the fatty acids to methane with up to 2 %O2. These findings underscore the pivotal role of FAB in the protection of syntrophic fatty acid-degrading communities under micro-aerobic conditions and emphasizes its significance in real-scale anaerobic digesters where strictly anaerobic conditions may not consistently be maintained.

Paracoccus spongiarum sp. nov., isolated from the marine sponge, Phakellia elegans.

A facultative anaerobic Gram-negative bacterium, designated as strain 2205BS29-5T, was isolated from a marine sponge, Phakellia elegans, in Beomseom on Jeju Island, Republic of Korea, and taxonomically characterized. The cells were catalase and oxidase positive, non-motile, coccoid-rod shaped and capable of poly-β-hydroxybutyrate production. Growth was observed at 10-37 °C (optimum, 25 °C) and pH 5.0-8.0 (optimum, pH 7.0), and in the presence of 0-9% NaCl (w/v) (optimum, 3.0-4.0%). The major cellular fatty acids and respiratory quinone were identified as summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c) and Q-10, respectively. The major polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, four phosphoglycolipids, two unidentified amino lipids and eight unidentified lipids. The DNA G+C content was 67.8%. Strain 2205BS29-5T was most closely represented by Paracoccus amoyensis 11-3T and P. caeni MJ17T with 97.8 and 97.5% 16S rRNA gene sequence similarities, respectively. Phylogenetic analyses based on 16S rRNA genes and whole-genome sequences showed that strain 2205BS29-5T was affiliated with the genus Paracoccus. Genomic analysis showed that strain 2205BS29-5T could synthesize vitamin B family (folate and cobalamin) and ectoine. The average nucleotide identity and digital DNA-DNA hybridization values between strain 2205BS29-5T and P. amoyensis 11-3T were 77.1% and 18.8%, respectively, and with P. caeni MJ17T were 78.4 and 21.2%, respectively. Based on phylogenetic, chemotaxonomic and genome relatedness analyses, strain 2205BS29-5T represents a novel species of the genus Paracoccus, for which the name Paracoccus spongiarum sp. nov. is proposed. The type strain is 2205BS29-5T (=LMG 33062T =KACC 23240T).

Comparison of the antibacterial activity of six medicinal plants, sodium hypochlorite, and chlorhexidine against enterococcus faecalis (In vitro study)

Enterococcus faecalis is a gram-positive, facultative anaerobic bacterium recognized for its resistance to various antimicrobial agents. This organism is associated with the failure of endodontic treatments, even when potent antimicrobial irrigants are employed. Numerous medicinal plants have demonstrated antimicrobial properties that could be potentially effective against this bacterium.To evaluate the antibacterial properties of six medicinal plants in comparison to sodium hypochlorite and chlorhexidine against E. faecalis.Antibacterial susceptibility tests against E. faecalis (ATCC 29212) were performed for 200 mg/ml ethanolic extracts of Acacia Senegal, Capparis decidua, Capparis micracantha, Acacia nilotica/ Adansonia, Dobera glabra, and Moringa oleifera by Agar Disc Diffusion method. Chlorhexidine 0.2% and Sodium hypochlorite 1% were used as positive controls, and ethanol 20% as a negative control. The diameters of the inhibition zones were measured. Acacia nilotica/adansonii leaves showed the largest inhibition zone diameter against E. faecalis. It displayed a significantly greater inhibitory effect against E. faecalis than Acacia Senegal (p-value =0.005), Capparis decidua (p-value =0.02), Capparis micracantha branches (p-value =0.000), Dobera glabra leaves (p-value =0.008), and Moringa olifera leaves (p-value =0.000).Acacia nilotica leaves displayed a similar inhibition zone diameter against E. faecalis as chlorhexidine gluconate 0.2%, but it showed no statistical significance. Acacia nilotica leaves (L) and pods (P), as well as Dobera glabra branches (B), displayed a larger inhibition zone diameter against E. faecalis than Sodium hypochlorite 1%, but with no statistical significance. The leaves of Acacia nilotica exhibit the most potent antibacterial properties against E. faecalis when compared to other plants parts. They outperform the antibacterial effectiveness of 1% sodium hypochlorite and demonstrate a similar antibacterial impact to that of 0.2% chlorhexidine. Therefore, Acacia nilotica leaves could serve as an ideal irrigant potentially substituting the chemical options.

Connecting the dots: Exploring the relationship between menstrual hygiene and bacterial vaginosis in eastern India

ABSTRACT Introduction: Menstruation is a normal physiological event that takes place in a rhythmic fashion during the reproductive period of a woman. Menstrual hygiene management (MHM) practices differ and depend on the individual’s socioeconomic status, local traditions and beliefs, and access to water and sanitation resources. Insufficient and incorrect information regarding menstruation and lack of knowledge and awareness leads to poor personal hygienic practices, which further leads to many infections. Bacterial vaginosis, the most common RTI, is characterized by an alteration in the vaginal micro biome with a decline in hydrogen peroxide producing Lactobacillus colonization and an overgrowth of facultative anaerobic bacteria like Gardnerella spp., Mobiluncus spp., etc. Aims: The primary objective of the study was to find out the association of bacterial vaginosis with menstrual hygiene practices. The secondary objective was to determine the prevalence of bacterial vaginosis among patients presenting with vaginal discharge to the outpatient department of a tertiary care hospital. Methods: Women in the reproductive age group 18-45 years having regular menstrual cycles were included in the study. Participants were enquired for sociodemographic data, menstrual hygiene practices and symptoms of abnormal vaginal discharge. High vaginal swab was collected for the symptomatic patients and sent to investigate for presence of bacterial vaginosis. Results and observation: The prevalence of BV was found to be 13% among symptomatic patients presenting with abnormal vaginal discharge. Apart from abnormal discharge, itching and burning sensation was also seen to have a positive association with bacterial vaginosis (p < 0.001). The women who used clothes as absorbent were more prone to develop BV than women using sanitary pad. The other parameters to have positive association with BV were decreased frequency of taking body bath. Unsatisfactory sanitation of latrine was found to be strongly associated with BV after adjusting for confounders. Conclusion: In conclusion, the result of this study provided a strong association between poor MHM practices with BV.

Unraveling mechanisms of selenium recovery by facultative anaerobic bacterium Azospira sp. A9D-23B in distinct reactor configurations.

Microbial processes are crucial in the redox transformations of toxic selenium oxyanions. This study focused on isolating an efficient selenate-reducing strain, Azospira sp. A9D-23B, and evaluating its capability to recover extracellular selenium nanoparticles (SeNPs) from selenium-laden wastewater in different reactor setups. Analysis using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) revealed significantly higher extracellular SeNPs production (99%) on the biocathode of the bioelectrochemical (BEC) reactor compared to the conventional bioreactor (65%). Further investigations into the selenate reductase activity of strain A9D-23B revealed distinct mechanisms of selenate reduction in BEC and conventional bioreactor settings. Notably, selenate reductases associated with the outer membrane and periplasm displayed higher activity (18.31 ± 3.8µmol/mg-min) on the BEC reactor's biocathode compared to the upflow anaerobic conventional bioreactor (3.24 ± 2.9µmol/mg-min). Conversely, the selenate reductases associated with the inner membrane and cytoplasm exhibited lower activity (5.82 ± 2.2µmol/mg-min) on the BEC reactor's biocathode compared to the conventional bioreactor (9.18 ± 1.6µmol/mg-min). However, the comparable kinetic parameter ( ) across cellular fractions in both reactors suggest that SeNP localization was influenced by enzyme activity rather than selenate affinity. Overall, the mechanism involved in selenate reduction to SeNPs and the strain's efficiency in detoxifying selenate below levels regulated by the U.S. Environmental Protection Agency has broad implications for sustainable environmental remediation strategies.

Oral Microbiocenosis in Cases of Inflammatory Periodontal Diseases in Children with Tuberculosis

Objective — to examine the microbial spectrum of the oral cavity in cases of inflammatory periodontal diseases of children with tuberculosis. Materials and methods. A study of the microbial habitat of oral biotopes and gingival surfaces was conducted in 97 children aged 6 to 17 years with inflammatory periodontal diseases and tuberculosis (treatment group). The control group consisted of 20 practically healthy children of the same age. The periodontal diseases were diagnosed according to M.F. Danilevsky’s classification (2000). The study of oral microbiocenosis and gingival surfaces in the examined groups of children was performed in accordance with Order No. 234 of the Ministry of Health of Ukraine as of 2006. Results and discussion. Aerobic, facultative anaerobic, and anaerobic bacteria persisted in the oral fluid and on the gingival surfaces of children with tuberculosis and inflammatory periodontal diseases. The most frequent colonies of bacteria were Streptococcus, in particular S. mutans, S. salivarius, S. β-haemolyticus, Staphylococcus (S. aureus, S. epidermidis).The significant evidence of Neisseria (N. catarrhalis) and Corynebacterium (C. xerosis) was revealed in the oral cavity and gingival surfaces of the examined children. The microflora of children from the treatment group revealed mostly Lactobacillus genus. The microbial associations of the examined children consisted of Candida, E. coli fungi. Smear microscopy revealed viruses. S. aureus was higher in the children from the treatment group as compared to the healthy children. In addition, the concentration of microorganisms was higher on the gingival surface versus the oral fluid and was more evident in the children from the treatment group. Conclusions. The obtained spectrum of the oral microbial contamination in the children with tuberculosis and inflammatory periodontal diseases revealed the persisting associations of aerobic, facultative anaerobic, and anaerobic bacteria. The inflammatory periodontal diseases in tuberculosis-infected children were accompanied by the evident increase in the frequency and concentration of microorganisms increasing with the higher severity of the specific process.

Unveiling wheat growth promotion potential of phosphate solubilizing Pantoea agglomerans PS1 and PS2 through genomic, physiological, and metagenomic characterizations.

Phosphorus is an abundant element in the earth's crust and is generally found as complex insoluble conjugates. Plants cannot assimilate insoluble phosphorus and require external supplementation as chemical fertilizers to achieve a good yield. Continuous use of fertilizers has impacted soil ecology, and a sustainable solution is needed to meet plant elemental requirements. Phosphate solubilizing microbes could enhance phosphorus bioavailability for better crop production and can be employed to attain sustainable agriculture practices. The current study unveils the biofertilizer potential of wheat rhizospheric bacteria through physiological, taxonomic, genomic, and microbiomics experimentations. Culture-dependent exploration identified phosphate-solubilizing PS1 and PS2 strains from the wheat rhizosphere. These isolates were rod-shaped, gram-negative, facultative anaerobic bacteria, having optimum growth at 37°C and pH 7. Phylogenetic and phylogenomic characterization revealed their taxonomic affiliation as Pantoea agglomerans subspecies PS1 & PS2. Both isolates exhibited good tolerance against saline (>10% NaCl (w/v), >11.0% KCl (w/v), and >6.0% LiCl (w/v)), oxidizing (>5.9% H2O2 (v/v)) conditions. PS1 and PS2 genomes harbor gene clusters for biofertilization features, root colonization, and stress tolerance. PS1 and PS2 showed nitrate reduction, phosphate solubilization, auxin production, and carbohydrate utilization properties. Treatment of seeds with PS1 and PS2 significantly enhanced seed germination percentage (p = 0.028 and p = 0.008, respectively), number of tillers (p = 0.0018), number of leaves (p = 0.0001), number of spikes (p = 0.0001) and grain production (p = 0.0001). Wheat rhizosphere microbiota characterizations indicated stable colonization of PS1 and PS2 strains in treated seeds at different feek stages. Pretreatment of seeds with both strains engineered the wheat rhizosphere microbiota by recruiting plant growth-promoting microbial groups. In vitro, In vivo, and microbiota characterization studies indicated the biofertilizer potential of Pantoea sp. PS1 & PS2 to enhance wheat crop production. The employment of these strains could fulfill plant nutrient requirements and be a substitute for chemical fertilizers for sustainable agriculture.

Identification and characterisation of carbapenem-resistant Streptococcus nidrosiense sp. nov. isolated from blood culture

BackgroundThis study aimed to investigate a highly resistant strain of Streptococcus sp. isolated from a patient with bloodstream infection and determine its taxonomic classification. MethodsThe strain was isolated from blood culture from a 65-year-old male patient admitted to St. Olavs University hospital, Trondheim, Norway, in 2023. Antimicrobial susceptibility testing as well as phenotypic and biochemical characterization were performed. Whole genome sequencing was conducted and genomic comparison to Streptococcus type strains was carried out. ResultsThe strain was initially identified as Streptococcus mitis/oralis but showed significant genetic differences, suggesting that it belonged to an undescribed species within the Streptococcus genus. Phenotypic and biochemical characterization identified the strain as a non-motile, facultative anaerobic bacterium with α-hemolysis. Antimicrobial susceptibility testing showed resistance to all beta-lactams tested. Genomic analyses confirmed the classification of the strain as a novel species, which was designated Streptococcus nidrosiense. ConclusionThis study combines conventional phenotypic tests with whole genome sequencing for accurate taxonomic classification of a bacterial strain isolated from blood culture. The identification of a novel species within the Streptococcus genus contributes to the understanding of microbial diversity and antibiotic resistance of the Streptococcus genus in clinical settings.

Fecal microbiome transplantation alleviates manganese-induced neurotoxicity by altering the composition and function of the gut microbiota via the cGAS–STING/NLRP3 pathway

Manganese (Mn) is an environmental pollutant, and overexposure can cause neurodegenerative disorders similar to Alzheimer's disease and Parkinson's disease that are characterized by β-amyloid (Aβ) overexpression, Tau hyperphosphorylation and neuroinflammation. However, the mechanisms of Mn neurotoxicity are not clearly defined. In our study, a knockout mouse model of Mn exposure combined with gut flora-induced neurotoxicity was constructed to investigate the effect of gut flora on Mn neurotoxicity. The results showed that the levels of Tau, p-Tau and Aβ in the hippocampus of C57BL/6 mice were greater than those in the hippocampus of control mice after 5 weeks of continuous exposure to manganese chloride (Mn content of 200 mg/L). Transplanted normal and healthy fecal microbiota from mice significantly downregulated Tau, p-Tau and Aβ expression and ameliorated brain pathology. Moreover, Mn exposure activated the cGAS–STING pathway and altered the cecal microbiota profile, characterized by an increase in Clostridiales, Pseudoflavonifractor, Ligilactobacillus and Desulfovibrio, and a decrease in Anaerotruncus, Eubacterium_ruminantium_group, Fusimonas and Firmicutes, While fecal microbiome transplantation (FMT) treatment inhibited this pathway and restored the microbiota profile. FMT alleviated Mn exposure-induced neurotoxicity by inhibiting activation of the NLRP3 inflammasome triggered by overactivation of the cGAS–STING pathway. Deletion of the cGAS and STING genes and FMT altered the gut microbiota composition and its predictive function. Phenotypic prediction revealed that FMT markedly decreased the abundances of anaerobic and stress-tolerant bacteria and significantly increased the abundances of facultative anaerobic bacteria and biofilm-forming bacteria after blocking the cGAS–STING pathway compared to the Mn-exposed group. FMT from normal and healthy mice ameliorated the neurotoxicity of Mn exposure, possibly through alterations in the composition and function of the microbiome associated with the cGAS–STING/NLRP3 pathway. This study provides a prospective direction for future research on the mechanism of Mn neurotoxicity.

Anaerobic bacteria in chronic wounds: Roles in disease, infection and treatment failure.

Infection is among the most common factors that impede wound healing, yet standard treatments routinely fail to resolve chronic wound infections. The chronic wound environment is largely hypoxic/anoxic, and wounds are predominantly colonised by facultative and obligate anaerobic bacteria. Oxygen (O2) limitation is an underappreciated driver of microbiota composition and behaviour in chronic wounds. In this perspective article, we examine how anaerobic bacteria and their distinct physiologies support persistent, antibiotic-recalcitrant infections. We describe the anaerobic energy metabolisms bacteria rely on for long-term survival in the wound environment, and why many antibiotics become less effective under hypoxic conditions. We also discuss obligate anaerobes, which are among the most prevalent taxa to colonise chronic wounds, yet their potential roles in influencing the microbial community and wound healing have been overlooked. All of the most common obligate anaerobes found in chronic wounds are opportunistic pathogens. We consider how these organisms persist in the wound environment and interface with host physiology to hinder wound healing processes or promote chronic inflammation. Finally, we apply our understanding of anaerobic physiologies to evaluate current treatment practices and to propose new strategies for treating chronic wound infections.

A cytochrome bd repressed by a MarR family regulator confers resistance to metals, nitric oxide, sulfide, and cyanide in Chromobacterium violaceum.

The terminal oxidases of bacterial respiratory chains rely on heme-copper (heme-copper oxidases) or heme (cytochrome bd ) to catalyze reduction of molecular oxygen to water. Chromobacterium violaceum is a facultative anaerobic bacterium that uses oxygen and other electron acceptors for respiration under conditions of varying oxygen availability. The C. violaceum genome encodes multiple respiratory terminal oxidases, but their role and regulation remain unexplored. Here, we demonstrate that CioAB, the single cytochrome bd from C. violaceum , protects this bacterium against multiple stressors that are inhibitors of heme-copper oxidases, including nitric oxide, sulfide, and cyanide. CioAB also confers C. violaceum resistance to iron, zinc, and hydrogen peroxide. This cytochrome bd is encoded by the cioRAB operon, which is under direct repression by the MarR-type regulator CioR. In addition, the cioRAB operon responds to quorum sensing and to cyanide, suggesting a protective mechanism of increasing CioAB in the setting of high endogenous cyanide production.

Enhanced steel corrosion inhibition through microbially induced carbonate precipitation with facultative anaerobic denitrifying bacterium

Denitrification processes are increasingly studied as a promising alternative to ureolytic microbially induced carbonate precipitation (MICP). This study investigates the capabilities of the newly isolated denitrifying bacterium, Stutzerimonas stutzeri CF3, in promoting calcium carbonate precipitation and enhancing steel corrosion resistance under both aerobic and anaerobic conditions. The facultative anaerobe was tested across a range of environmental parameters including pH levels (7.5–11.5), C/N ratios (5−15), NaCl salinity (0–5 %), and Ca²⁺ concentrations (0–30 mmol), to determine its adaptability and effectiveness in precipitating calcium carbonate. Our findings reveal that S. stutzeri CF3 not only survives but thrives under extreme conditions, demonstrating significant nitrate removal and robust calcium carbonate precipitation, particularly in high salinity and variable pH environments. Furthermore, the study examines the implications of S. stutzeri CF3 on steel corrosion, particularly Q235 steel, using Tafel polarization techniques, demonstrating enhanced corrosion resistance. These results underscore the dual utility of S. stutzeri CF3 in microbial self-healing concrete applications, pointing to its potential to improve the durability and integrity of construction materials by leveraging its versatile metabolic pathways.

Antimicrobial activity of calcium hydroxide, calcium oxide, and mineral trioxide aggregate paste against α-Hemolytic Streptococcus

Background: The bacteria mostly found in the root canals are aerobic and facultative anaerobic bacteria, such as α-Hemolytic Streptococcus. Calcium hydroxide has alkaline characteristics with pH of 12.5, and antimicrobial properties. Calcium oxide is hydrophilic and has a smaller molecular weight than calcium hydroxide. Mineral trioxide aggregate (MTA) has alkaline properties, good biocompatibility, stimulates healing and inhibits bacterial growth. Purpose: The purpose of this study was to examine the differences of antimicrobial activity between calcium hydroxide, calcium oxide, and mineral trioxide aggregate (MTA), also to find which of these materials has the highest antimicrobial activity. Methods: The design of this study was a post-test only control group design. The study subjects were divided into 4 groups. K (-) was control group without any treatment, P1 was treated with calcium hydroxide, P2 was treated with calcium oxide, and P3 was treated with MTA. Each group consisted of 7 samples. The α-Hemolytic Streptococcus were spread on Mueller Hinton agar. Antimicrobial test was using diffusion method and diameter of inhibition zones were measured with caliper. Results: Average inhibitory zone of each sample was P1 (30.9643 mm ± 0,7431), P2 (35,2357 mm ± 0,7099), P3 (28,6 mm ± 1,5532). Tukey HSD test showed significances results between samples P1 and P2 (p=0,001), P1 and P3 (p=0,002), P2 and P3 (p=0,001). Conclusion: The highest antimicrobial activity against α-Hemolytic Streptococcus was calcium oxide followed by calcium hydroxide and MTA.

Aggregatibacter actinomycetemcomitans: From the Oral Cavity to the Heart Valves.

Aggregatibacter actinomycetemcomitans (A. actinomycetecomitans) is a Gram-negative bacterial species that is an essential component of the oral microbiota. Due to its aggregative properties, it plays a role in the pathogenesis of human diseases. The presence of the surface proteins Fim, Briae, and microvesicles enables the bacterium to adhere to the epithelial surface and the tooth's surface. The presence of leukotoxin A (LtxA), which plays an important role in the pathogenicity of the bacterium, has been associated with both periodontitis and the etiology of rheumatoid arthritis (RA). A. actinomycetecomitans is also associated with several other systemic diseases and complications, such as endocarditis and different abscesses. In addition to leukotoxin A, A. actinomycetecomitans possesses several different virulence factors, including bacteriocins, chemotaxis inhibitory factors, cytotoxic factors, Fc-binding proteins, immunosuppressive factors, lipopolysaccharide collagenase, fibroblast inhibitory factors, antibiotic resistance determinants, adhesins, invasive factors and factors that inhibit the function of polymorphonuclear leukocytes. The ability of A. actinomycetemcomitans lipopolysaccharide to induce macrophages to secrete the interleukins IL-1, IL-1β, and tumor necrosis factor (TNF) is of considerable importance. The primary etiologic factor in the pathogenesis of periodontal disease is the oral biofilm colonized by anaerobic bacteria. Among these, A. actinomycetemcomitans occupies an important place as a facultative anaerobic bacterium. In addition, A. actinomycetemcomitans possesses many virulence factors that contribute to its potential to cause cancer. This article provides an overview of the virulence factors of A. actinomycetecomitans and its association with various systemic diseases, its oncogenic potential, and the treatment options for infections caused by A. actinomycetecomitans.

Insight into a single-chamber air-cathode microbial fuel cell for nitrate removal and ecological roles.

Bioelectrochemical systems are sustainable and potential technology systems in wastewater treatment for nitrogen removal. The present study fabricated an air-cathode denitrifying microbial fuel cell (DNMFC) with a revisable modular design and investigated metabolic processes using nutrients together with the spatiotemporal distribution characteristics of dominated microorganisms. Based on the detection of organics and solvable nitrogen concentrations as well as electron generations in DNMFCs under different conditions, the distribution pattern of nutrients could be quantified. By calculation, it was found that heterotrophic denitrification performed in DNMFCs using 56.6% COD decreased the Coulombic efficiency from 38.0% to 16.5% at a COD/NO3 --N ratio of 7. Furthermore, biological denitrification removed 92.3% of the nitrate, while the residual was reduced via electrochemical denitrification in the cathode. Correspondingly, nitrate as the electron acceptor consumed 16.7% of all the generated electrons, and the residual electrons were accepted by oxygen. Microbial community analysis revealed that bifunctional bacteria of electroactive denitrifying bacteria distributed all over the reactor determined the DNMFC performance; meanwhile, electroactive bacteria were mainly distributed in the anode biofilm, anaerobic denitrifying bacteria adhered to the wall, and facultative anaerobic denitrifying bacteria were distributed in the wall and cathode. Characterizing the contribution of specific microorganisms in DNMFCs comprehensively revealed the significant role of electroactive denitrifying bacteria and their cooperative relationship with other functional bacteria.

Comparative evaluation of culture results and composition of microbiome of removed tonsils due to distant focal disease or other reasons. Aprospective pilot study.

The aim of this prospective pilot study was to compare culture and microbiome results of the removed tonsils of patients with assumed distant focal disease (11 patients) and those who underwent a tonsillectomy, due to other reasons, such as recurrent tonsillitis, tonsil stones or snoring (nine patients). Aerobic culture was carried out for samples taken from the surface of the tonsils by swabs before tonsillectomy for all 20 patients. The squeezed detritus and the tissue samples of removed tonsils, taken separately for the right and left tonsils, were incubated aerobically and anaerobically. The microbiome composition of tissue samples of removed tonsils was also evaluated. Based on the culture results of the deep samples Staphylococcus aureus was the dominating pathogen, besides a great variety of anaerobic and facultative anaerobic bacteria present in the oral microbiota in those patients who underwent tonsillectomy due to distant focal diseases. Microbiome study of the core tissue samples showed a great diversity on genus and species level among patients of the two groups however, S. aureus and Prevotella nigrescens were present in higher proportion in those, whose tonsils were removed due to distant focal diseases. Our results may support previous findings about the possible triggering role of S. aureus and P.nigrescens leading to distant focal diseases. Samples taken by squeezing the tonsils could give more information about the possible pathogenic/triggering bacteria than the surface samples cultured only aerobically.