Bacterial Reduction Research Articles

Pilot randomized experimental study evaluating isopropyl alcohol and ultraviolet-C radiation in the disinfection of healthcare workers' smartphones

Smartphones in medical settings pose infection risks due to harbouring pathogenic bacteria. This pilot study assessed the effectiveness duration of sanitization methods, focusing on 70% isopropyl alcohol wipes and ultraviolet-C (UVC) boxes, aiming to obtain preliminary data on the reduction in total bacterial load 3h post-sanitization. A randomized monocentric trial with two intervention arms (wipes and UVC boxes) was designed. As participants, healthcare workers from three wards at Fondazione Policlinico Universitario 'A. Gemelli' IRCCS Hospital were recruited, stratified by ward, and block randomized within each ward to control confounders. Seventy-one healthcare workers, mostly nurses (62%) were included in the study. Initial bacterial load reduction was significant with both disinfection techniques, but after 3h both methods showed increased bacterial levels, with wipes displaying potentially higher residual efficacy (P=0.056). To adequately size a trial (89% power, significance level 0.05) for assessing the residual efficacy of alcohol-impregnated wipes compared with UVC boxes at 3h post-sanitization, 503 professionals per group were required. This study highlights the necessity for guidelines on hospital smartphone sanitization and educational initiatives for healthcare workers and patients. Further studies, adequately sized, are necessary to determine optimal sanitization intervals and assess pathogen transmission risks.

Growth-dependent cr(VI) reduction by Alteromonas sp. ORB2 under haloalkaline conditions: toxicity, removal mechanism and effect of heavy metals.

Bacterial reduction of hexavalent chromium (VI) to chromium (III) is a sustainable bioremediation approach. However, the Cr(VI) containing wastewaters are often characterized with complex conditions such as high salt, alkaline pH and heavy metals which severely impact the growth and Cr(VI) reduction potential of microorganisms. This study investigated Cr(VI) reduction under complex haloalkaline conditions by an Alteromonas sp. ORB2 isolated from aerobic granular sludge cultivated from the seawater-microbiome. Optimum growth of Alteromonas sp. ORB2 was observed under haloalkaline conditions at 3.5-9.5% NaCl and pH 7-11. The bacterial growth in normal culture conditions (3.5% NaCl; pH 7.6) was not inhibited by 100mg/l Cr(VI)/ As(V)/ Pb(II), 50mg/l Cu(II) or 5mg/l Cd(II). Near complete reduction of 100mg/l Cr(VI) was achieved within 24h at 3.5-7.5% NaCl and pH 8-11. Cr(VI) reduction by Alteromonas sp. ORB2 was not inhibited by 100mg/L As(V), 100mg/L Pb(II), 50mg/L Cu(II) or 5mg/L Cd(II). The bacterial cells grew in the medium with 100mg/l Cr(VI) contained lower esterase activity and higher reactive oxygen species levels indicating toxicity and oxidative stress. In-spite of toxicity, the cells grew and reduced 100mg/l Cr(VI) completely within 24h. Cr(VI) removal from the medium was driven by bacterial reduction to Cr(III) which remained in the complex medium. Cr(VI) reduction was strongly linked to aerobic growth of Alteromonas sp. The Cr(VI) reductase activity of cytosolic protein fraction was pronounced by supplementing with NADPH in vitro assays. This study demonstrated a growth-dependent aerobic Cr(VI) reduction by Alteromonas sp. ORB2 under complex haloalkaline conditions akin to wastewaters.

Proliferation of psychrotrophic bacteria in cold-stored platelet concentrates.

Platelet concentrates (PC) are stored at 20-24°C to maintain platelet functionality, which may promote growth of contaminant bacteria. Alternatively, cold storage of PC limits bacterial growth; however, data related to proliferation of psychotrophic species in cold-stored PC (CSP) are scarce, which is addressed in this study. Eight laboratories participated in this study with a pool/split approach. Two split PC units were spiked with ~25 colony forming units (CFU)/PC of Staphylococcus aureus, Klebsiella pneumoniae, Serratia liquefaciens, Pseudomonas fluorescens and Listeria monocytogenes. One unit was stored under agitation at 20-24°C/7 days while the second was stored at 1-6°C/no agitation for 21 days. PC were sampled periodically to determine bacterial loads. Five laboratories repeated the study with PC inoculated with lyophilized inocula (~30 CFU/mL) of S. aureus and K. pneumoniae. All species proliferated in PC stored at 20-24°C, reaching concentrations of ≤109 CFU/mL by day 7. Psychrotrophic P. fluorescens and S. liquefaciens proliferated in CSP to ~106 CFU/mL and ~105 CFU/mL on days 10 and 17 of storage, respectively, followed by L. monocytogenes, which reached ~102 CFU/mL on day 21. S. aureus and K. pneumoniae did not grow in CSP. Psychrotrophic bacteria, which are relatively rare contaminants in PC, proliferated in CSP, with P. fluorescens reaching clinically significant levels (≥105 CFU/mL) before day 14 of storage. Cold storage reduces bacterial risk of PC to levels comparable with RBC units. Safety of CSP could be further improved by implementing bacterial detection systems or pathogen reduction technologies if storage is beyond 10 days.

Efficient Generation of Plasma‐Activated Aerosols with High Concentrations of Reactive Species via Silicon Dioxide Coated Surface Acoustic Wave Devices

AbstractAn effective method to deliver plasma‐activated water onto contaminated surfaces is with a surface acoustic wave (SAW) nebulizer that can efficiently produce plasma‐activated aerosols. While higher reactive species concentrations in the plasma‐activated aerosols promote more efficient bacterial inactivation and hence reduce the amount of aerosols needed to completely eradicate the bacteria colonies, higher concentrations of reactive species themselves are found to lead to lower nebulization rates due to the increased electrical conductivity of the solution. To circumvent this problem, it is shown that coating the SAW substrate with a thin insulating layer of silicon dioxide (SiO2) can significantly mitigate the nebulization rate reduction. Specifically, when the electrical conductivity increases from 0.25 to 4.0 mS cm−1, the 62% drop in the nebulization rate is observed with the uncoated SAW devices is substantially reduced to 19% simply with the SiO2 coating. This can be attributed to the synergistic effects of increased wettability and the suppression of the electrical body force acting on the liquid film. The concomitant increase in the bacterial colony reduction from 17% to 76% demonstrates this solution to be a facile yet effective way of enhancing the efficiency for spray‐based bacterial inactivation on contaminated surfaces.

Geochemical and Isotopic Characteristics of the Emir Geothermal Waters in Kula Area, Western Anatolia

In this study, we investigate chemical and isotopic characteristics of thermal waters of the Emir geothermal field in the Kula region, which hosts the youngest volcanism in Turkey. Studied thermal waters with temperature and electrical conductivity values of 21–63 °C and 3840 to 5210 μS/cm are of Na–HCO3 type and have neutral character. δ18O and δD of thermal waters are − 9.40 to − 8.41‰ and − 64.16 to − 56.38‰ (VSMOW) and indicate a meteoric source with local recharge. Tritium values of thermal waters in the Emir geothermal field are mostly < 1 TU signifying a deep circulation. Positive δ13C values (1.32–4.46‰ VPDB) imply that carbon is derived dominantly from marine limestone and dominantly from endogenic CO2. δ18O and δ34S of dissolved sulfate yield that marine limestone is the source of sulfur in thermal waters, which are partly affected by sulfide oxidation and bacterial reduction processes. At discharge temperatures, Emir thermal waters are oversaturated with respect to albite, aragonite, calcite, α-cristobalite, dolomite, gibbsite, illite, K-feldspar, kaolinite, muscovite and quartz but undersaturated for anhydrite and wairakite. The activity diagrams suggest that high Na+ and K+ concentrations in waters are attributed to dissolution of muscovite, K-feldspar and albite. Chemical and isotopic compositions of the Emir thermal waters are controlled by a combination of processes including water–rock interaction, dissolution/precipitation and ion exchange. Various chemical and isotopic geothermometers applied to the thermal waters yielded reservoir temperatures in the range of 80–125 °C. Paleo-temperatures estimated from δ18O values of travertines and thermal waters (isotope fractionation) are consistent with modern discharge temperatures.

Design, optimization and pharmaceutical characterization of wound healing film dressings with chloramphenicol and ibuprofen

Objective The aim of the present study was to develop and optimize a wound dressing film loaded with chloramphenicol (CAM) and ibuprofen (IBU) using a Quality by Design (QbD) approach. Significance The two drugs have been combined in the same dressing as they address two critical aspects of the wound healing process, namely prevention of bacterial infection and reduction of inflammation and pain related to injury. Methods Three critical formulation variables were identified, namely the ratios of Kollicoat SR 30D, polyethylene glycol 400 and polyvinyl alcohol. These variables were further considered as factors of an experimental design, and 17 formulations loaded with CAM and IBU were prepared via solvent casting. The films were characterized in terms of dimensions, mechanical properties and bioadhesion. Additionally, the optimal formulation was characterized regarding tensile properties, swelling behavior, water vapor transmission rate, surface morphology, thermal behavior, goniometry, in vitro drug release, cell viability, and antibacterial activity. Results The film was optimized by setting minimal values for the folding endurance, adhesive force and hardness. The optimally formulated film showed good fluid handling properties in terms of swelling behavior and water vapor transmission rate. IBU and CAM were released from the film up to 80.9% and 82.5% for 8 h. The film was nontoxic, and the antibacterial activity was prominent against Micrococcus spp. and Streptococcus pyogenes. Conclusions The QbD approach was successfully implemented to develop and optimize a novel film dressing promising for the treatment of low-exuding acute wounds prone to infection and inflammation.

Antimicrobial nanolayer films of chloroxylenol–carboxyethylchitosan–modified silver nanoparticles for enhanced surgical suture performance

Antimicrobial surgical suture materials incorporating chloroxylenol-carboxyethylchitosan-modified silver nanoparticles (CECSX-AgNPs) were successfully prepared using the Layer-by-Layer (LbL) deposition technique. Chitosan (CS) was covalently affixed with chloroxylenol as hydrophobic functional groups (PCMX), yielding chloroxylenol-chitosan (CSX) and later hydrophilic acrylic acid onto the CSX skeleton, providing a novel water-soluble antimicrobial agent of chloroxylenol-carboxyethylchitosan (CECSX). 1H NMR confirmed the successful substitution of PCMX and acrylic acid onto CS, with %DSPCMX and %DSAA of 8.0 and 33.0, respectively. CECSX successfully stabilized AgNPs via the chemical reduction method, resulting in CECSX modified AgNPs. The colloidal solution exhibited a yellowish hue, spherical shape, monodispersity with an average particle size of 4.8 ± 2.4 nm, and a zeta potential value of −20.97 ± 0.03 mV. Minimum inhibitory concentration (MIC) values for CECSX-AgNPs against E. coli (ATCC25922), S. aureus (ATCC25923), and A. baumanii (ATCC19606) were determined as 25, 12.5, and 1.56 mg/L, respectively. Using the LbL deposition technique, CECSX-AgNPs were successfully deposited onto various suture materials including cotton, polyamide, and polypropylene. Remarkably, CECSX-AgNPs coated surgical sutures exhibited the highest bacterial reduction of 99.99 %. These findings underscore the efficacy of CECSX as a high-performance stabilizing agent for AgNPs production, providing outstanding antibacterial activity on diverse surgical suture materials and promoting the wound healing process.

Antimicrobial action and cytotoxicity of hypochlorous acid obtained from an innovative electrolytic device – An in vitro study

ObjectiveThis study evaluated the antimicrobial effect and cytotoxicity of hypochlorous acid(HClO) obtained from an innovative electrolytic device. DesignThe root canals of fifty extracted human teeth were inoculated with Enterococcus faecalis and divided into 5 groups (n = 10): DW (control); 2% chlorhexidine gel(CHX); 2.5% sodium hypochlorite(NaOCl); 250 ppm HClO and 500 ppm HClO. The counting of colony forming units evaluated the decontamination potential of each group. Cytotoxicity was evaluated after inoculation of tested protocols in fibroblastic cells for 3 min, calculating the cell viability. Specific statistical analysis was performed (α = 5%). ResultsThe highest bacterial reduction was observed in experimental groups, with no statistical differences from each other (p > 0.05). The highest number of viable cells was observed in control group, followed by 250 ppm HClO and 500 ppm HClO groups, with statistical differences from each other (p < 0.05). ConclusionsIt could be concluded that HClO presented high antimicrobial activity and low cytotoxicity at both tested concentrations.

Trace Element and Sulfur Isotope Signatures of Volcanogenic Massive Sulfide (VMS) Mineralization: A Case Study from the Sunnhordland Area in SW Norway

The Sunnhordland area in SW Norway hosts more than 100 known mineral occurrences, mostly of volcanogenic massive sulfide (VMS) and orogeny Au types. The VMS mineralization is hosted by plutonic, volcanic and sedimentary lithologies of the Lower Ordovician ophiolitic complexes. This study presents new trace element and δ34S data from VMS deposits hosted by gabbro and basalt of the Lykling Ophiolite Complex and organic-rich sediments of the Langevåg Group. The Alsvågen gabbro-hosted VMS mineralization exhibits a significant Cu content (1.2 to &gt;10 wt.%), with chalcopyrite and cubanite being the main Cu-bearing minerals. The enrichment of pyrite in Co, Se, and Te and the high Se/As and Se/Tl ratios indicate elevated formation temperatures, while the high Se/S ratio indicates a contribution of magmatic volatiles. The δ34S values of the sulfide phases also support a substantial influx of magmatic sulfur. Chalcopyrite from the Alsvågen VMS mineralization shows significant enrichment in Se, Ag, Zn, Cd and In, while pyrrhotite concentrates Ni and Co. The Lindøya basalt-hosted VMS mineralization consists mainly of pyrite and pyrrhotite. Pyrite is enriched in As, Mn, Pb, Sb, V, and Tl. The δ34S values of sulfides and the Se/S ratio in pyrite suggest that sulfur was predominantly sourced from the host basalt. The Litlabø sediment-hosted VMS mineralization is also dominated by pyrite and pyrrhotite. Pyrite is enriched in As, Mn, Pb, Sb, V and Tl. The δ34S values, which range from −19.7 to −15.7 ‰ VCDT, point to the bacterial reduction of marine sulfate as the main source of sulfur. Trace element characteristics of pyrite, especially the Tl, Sb, Se, As, Co and Ni concentrations, together with their mutual ratios, provide a solid basis for distinguishing gabbro-hosted VMS mineralization from basalt- and sediment-hosted types of VMS mineralization in the study area. The distinctive trace element features of pyrite, in conjunction with its sulfur isotope signature, have been identified as a robust tool for the discrimination of gabbro-, basalt- and sediment-hosted VMS mineralization.

Preliminary Investigation towards the Use of Infrared Technology for Raw Milk Treatment.

Infrared (IR) technology offers a promising solution for reducing microbiological loads in various food types while preserving their quality traits, such as flavour. However, research on IR's application in complex matrices is limited. Therefore, our preliminary study aimed to evaluate its effectiveness in sanitizing bovine raw milk. We assessed the bacterial count before and after IR treatment by comparing volatile organic compound profiles via headspace extraction and GC/MS analysis. Our findings showed that higher energy levels led to a greater bacterial reduction. IR85 was the most effective in reducing Coliforms and Enterobacteriaceae in non-homogenised samples, with a reduction ranging from -1.01 to >-2.99 and from -1.66 to -3.09 Log CFU/mL, respectively. IR60 and 70 showed no efficacy, while IR80 had intermediate but still satisfactory effect. IR85 notably affected volatile compounds, particularly increasing hexanal (from 0.08 to 4.21 ng g-1) and dimethyl sulphone (from 10.76 to 26.40 ng g-1), while IR80 better preserved the aroma profile. As a result, only IR80 was tested with homogenised raw milk, demonstrating significant bacterial reduction (from >2.39 to 3.06 Log CFU/mL for Coliforms and from 1.90 to >2.45 Log CFU/mL for Enterobacteriaceae) and maintaining the aroma profile quality.

Optimizing Antimicrobial Efficacy: Investigating the Impact of Zinc Oxide Nanoparticle Shape and Size.

Zinc oxide nanoparticles (ZnO NPs) have been investigated due to their distinct properties, variety of structures and sizes, and mainly for their antimicrobial activity. They have received a positive safety evaluation from the European Food Safety Authority (EFSA) for packaging applications as transparent ultraviolet (UV) light absorbers based on the absence of significant migration of zinc oxide in particulate form. ZnO NPs with different morphologies (spherical, flower, and sheet) have been synthesized via different sol-gel methods and extensively characterized by several solid-state techniques, namely vibrational spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), Fourier Transform Infrared Spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-VIS), electron paramagnetic resonance (EPR), and nitrogen adsorption-desorption isotherms. The ZnO NPs were assessed for their antibacterial activity against Escherichia coli (gram-negative bacteria) and Staphylococcus aureus (gram-positive bacteria) to study the influence of morphology and size on efficacy. ZnO NPs with different morphologies and sizes demonstrated antimicrobial activity against both bacteria. The highest microbial cell reduction rate (7-8 log CFU mL-1 for E. coli and 6-7 log CFU mL-1 for S. aureus) was obtained for the sheet- and spherical-shaped NPs as a result of the high specific surface area. In fact, the higher surface areas of the sheet- and spherical-shaped nanoparticles (18.5 and 13.4 m2 g-1, respectively), compared to the flower-shaped NPs (5.3 m2g-1), seem to promote more efficient bacterial cell reduction. The spherical-shaped particles were also smaller (31 nm) compared with the flower-shaped (233 × 249 nm) ones. The flower ZnO NP resulted in a 4-5 log CFU mL-1 reduction for E. coli and 3-4 log CFU mL-1 reduction for S. aureus. The lower apparent antibacterial activity of the flower-shaped could be associated with either the lack of defects on the particle core or the shape shielding effect. Compared to S. aureus, E. coli seems to be less resistant to ZnO NPs, which may be explained by the characteristics of its cell membrane. With simple synthesis techniques, which do not allow the size and shape of the nanoparticles to be controlled simultaneously, it is a challenge to elucidate the effect of each of these two parameters on antibacterial performance.

Evaluation of bacterial safety approaches of platelet blood concentrates: bacterial screening and pathogen reduction.

This mini-review analyzed two approaches to screening bacterial contamination and utilizing pathogen reduction technology (PRT) for Platelet concentrates (PCs). While the culture-based method is still considered the gold standard for detecting bacterial contamination in PCs, efforts in the past two decades to minimize transfusion-transmitted bacterial infections (TTBIs) have been insufficient to eliminate this infectious threat. PRTs have emerged as a crucial tool to enhance safety and mitigate these risks. The evidence suggests that the screening strategy for bacterial contamination is more successful in ensuring PC quality, decreasing the necessity for frequent transfusions, and improving resistance to platelet transfusion. Alternatively, the PRT approach is superior regarding PC safety. However, both methods are equally effective in managing bleeding. In conclusion, PRT can become a more prevalent means of safety for PCs compared to culture-based approaches and will soon comprehensively surpass culture-based bacterial contamination detection methods.

The isotopic signature of UV during bacterial reduction

The isotopic signature of UV during bacterial reduction

Enhancing Antibiotic Efficacy in Regenerative Endodontics by Improving Biofilm Susceptibility

IntroductionVarious strategies have been researched to enhance the susceptibility of biofilms, given their tolerance to antibiotics. This study evaluated the effect of the anti-microbial peptide nisin in association with antibiotics used in regenerative endodontics, exploring different treatment times and biofilm growth conditions. MethodsA mixture of 10 bacterial species was cultivated on dentin specimens anaerobically for 21 days. Biofilms were treated with 1 mL of high-purity nisin Z (nisin ZP, 200 μg/mL) and a triple antibiotic mixture (TAP: ciprofloxacin + metronidazole + minocycline, 5 mg/mL), alone or in combination. The effectiveness of antimicrobial agents was assessed after 1 and 7 days. During the 7-day period, biofilms were treated under 2 conditions: a single dose in a nutrient-depleted setting (ie, no replenishment of growth medium) and multiple doses in a nutrient-rich environment (ie, renewal of medium and antimicrobial agents every 48 h). After treatments, biofilm cells were dispersed, and total colony-forming units were counted. ResultsAfter 1 d-treatment, nisin ZP + TAP resulted in 2-log cell reduction compared to TAP alone (P < .05). After 7 d-treatment with a single dose, nisin ZP + TAP and TAP reduced bacteria to nonculturable levels (P < .05), whereas repeated antimicrobial doses did not eliminate bacteria in a nutrient-rich environment. No bacterial reduction was observed with nisin ZP alone in any treatment time. ConclusionsThe additional use of nisin improved the TAP activity only after a short exposure time. Longer exposure to TAP or nisin + TAP in a nutrient-deprived environment effectively eliminated biofilms.

Effect of Propolis nanoparticles versus sodium hypochlorite as root canal irrigant on postoperative pain and bacterial reduction in mandibular premolars with necrotic pulps: a randomized clinical trial

Effect of Propolis nanoparticles versus sodium hypochlorite as root canal irrigant on postoperative pain and bacterial reduction in mandibular premolars with necrotic pulps: a randomized clinical trial

Pharmacokinetic and pharmacodynamic evaluation of nitrofurantoin against Escherichia coli in a murine urinary tract infection model.

The antimicrobial agent nitrofurantoin is becoming increasingly important for treatment of urinary tract infections (UTIs) due to widespread occurrence of multidrug-resistant Escherichia coli. Despite many years of use, little data on nitrofurantoin pharmacokinetics (PK) or -dynamics (PD) exist. The objective of this study was to (i) evaluate the pharmacokinetics of nitrofurantoin in a mouse model and (ii) use that data to design an in vivo dose fractionation study in an experimental model of UTI with E. coli for determination of the most predictive PK/PD index. Nitrofurantoin concentrations in urine were approximately 100-fold larger than concentrations in plasma after oral administration of 5, 10, and 20 mg/kg nitrofurantoin. The area under the curve over the minimum inhibitory concentration (AUC/MIC) was weakly correlated to bacterial reduction in urine (r2 = 0.24), while no such correlation was found for the time that nitrofurantoin stayed above the MIC (T > MIC). Increasing size of single-dose treatment was significantly correlated to eradication of bacteria in the urine, while this was not apparent when the same doses were divided in 2 or 3 doses 8 or 12 h apart. In conclusion, the results indicate that nitrofurantoin activity against E. coli in urine is driven by AUC/MIC.

Biomarker signatures and depositional environment of ore-bearing black shale in the Luishia Cu–Co deposit, Democratic Republic of Congo: Implications for regional copper mineralization

The Central African Copperbelt is a globally important sediment-hosted stratiform copper cluster, with regional Cu–Co deposits controlled by Neoproterozoic rift basin. Ore formation in the Copperbelt involves multiple stages of mineralization during diagenesis, basin inversion, and collisional orogeny. Understanding the depositional environment of ore-hosting rocks is crucial for revealing the geological settings and pre-orogenic ore genesis. This paper presents a biomarker study focusing on the ore-bearing black shale in the Luishia Cu–Co deposit, Democratic Republic of Congo. The research investigates thermal maturity, source, and depositional environment of organic matter through rock organic carbon and pyrolysis analysis, chloroform bitumen “A” group component analysis, as well as saturated hydrocarbon gas chromatography-mass spectrometry (GC-MS) analysis. The results indicate significant thermal maturation of organic matter in Luishia black shale. Bacteria are identified as the primary source of organic matter followed by red algae and green algae. The sedimentary environment is characterized by a restricted rift basin under shallow marine conditions with a stratified water column. The processes of bacterial sulphate reduction (BSR) and thermochemical sulphate reduction (TSR) significantly influence the mineralization during diagenesis and basin inversion, respectively. Enhanced thermal maturity promotes methane generation which plays a role in reducing anhydrite and subsequently precipitating ore minerals. The findings have important implications for regional exploration strategies.

Hydrogeochemical conditions of submarine and terrestrial karst sulfur springs in the Northern Adriatic

Submarine springs near Izola, in the Northern Adriatic Sea, appear in funnel-shaped depressions and smell strongly of sulfur. Along the Mediterranean coast there are many submarine karst springs containing brackish or fresh water, but submarine sulfur springs are not particularly common. Three submarine sulfur springs and one terrestrial sulfur spring were investigated to better understand the water properties, water–rock interaction within the aquifer, and to explore the origin of the spring water. Groundwater and seawater samples were also collected for comparison. Based on the geological setting, physicochemical parameters, hydrogeochemical data, and stable isotope data (δ18O, δ2H, δ13CDIC, δ34SSO4, δ18OSO4), we can affirm that (1) the large concentration of seawater in the submarine springs samples is due to sampling challenges; (2) springs recharge from precipitation where confined karst aquifers outcrop; (3) deep water circulation is indicated; (4) redox conditions can provide a suitable environment for bacterial reduction of the marine or organic sulfate to the odorous H2S; (5) geological data suggests that the coals beneath the alveolinic-nummulitic limestones are the source of sulfur. A multi-parameter and interdisciplinary approach has proven important in assessing submarine sulfur springs affected by seawater input.

Discovery of a Gut Bacterial Metabolic Pathway that Drives α-Synuclein Aggregation.

Parkinson's disease (PD) etiology is associated with aggregation and accumulation of α-synuclein (α-syn) proteins in midbrain dopaminergic neurons. Emerging evidence suggests that in certain subtypes of PD, α-syn aggregates originate in the gut and subsequently spread to the brain. However, mechanisms that instigate α-syn aggregation in the gut have remained elusive. In the brain, the aggregation of α-syn is induced by oxidized dopamine. Such a mechanism has not been explored in the context of the gastrointestinal tract, a niche harboring 46% of the body's dopamine reservoirs. Here, we report that Enterobacteriaceae, a bacterial family prevalent in human gut microbiotas, induce α-syn aggregation. More specifically, our in vitro data indicate that respiration of nitrate by Escherichia coli K-12, which results in production of nitrite that mediates oxidation of Fe2+ to Fe3+, creates an oxidizing redox potential. These oxidizing conditions enabled the formation of dopamine-derived quinones and α-syn aggregates. Exposing nitrite, but not nitrate, to enteroendocrine STC-1 cells induced aggregation of α-syn that is natively expressed in these cells, which line the intestinal tract. Taken together, our findings indicate that bacterial nitrate reduction may be critical for initiating intestinal α-syn aggregation.

In silico agent-based modeling approach to characterize multiple in vitro tuberculosis infection models.

In vitro models of Mycobacterium tuberculosis (Mtb) infection are a valuable tool for examining host-pathogen interactions and screening drugs. With the development of more complex in vitro models, there is a need for tools to help analyze and integrate data from these models. To this end, we introduce an agent-based model (ABM) representation of the interactions between immune cells and bacteria in an in vitro setting. This in silico model was used to simulate both traditional and spheroid cell culture models by changing the movement rules and initial spatial layout of the cells in accordance with the respective in vitro models. The traditional and spheroid simulations were calibrated to published experimental data in a paired manner, by using the same parameters in both simulations. Within the calibrated simulations, heterogeneous outputs are seen for bacterial count and T cell infiltration into the macrophage core of the spheroid. The simulations also predict that equivalent numbers of activated macrophages do not necessarily result in similar bacterial reductions; that host immune responses can control bacterial growth in both spheroid structure dependent and independent manners; that STAT1 activation is the limiting step in macrophage activation in spheroids; and that drug screening and macrophage activation studies could have different outcomes depending on the in vitro culture used. Future model iterations will be guided by the limitations of the current model, specifically which parts of the output space were harder to reach. This ABM can be used to represent more in vitro Mtb infection models due to its flexible structure, thereby accelerating in vitro discoveries.