Live Bacteria Research Articles

Effects of dietary supplementation of a blend of Saccharomyces cerevisiae, multiple live probiotic bacteria, and their fermentation products on performance, health, and rumen bacterial community of newly weaned beef steers during a 56-d receiving period.

We examined the effects of a blend of Saccharomyces cerevisiae, multiple live probiotic bacteria, and their fermentation products on performance, health, and the ruminal bacterial community of newly weaned beef steers during a 56-d receiving period. Forty newly weaned Angus crossbred steers (221 ± 25.6kg BW; 180 ± 17 d of age) were stratified by body weight (BW) into four pens (10 steers per pen) such that each pen had a similar average BW at the beginning of the experiment. The pens were randomly assigned to receive a corn silage basal diet (CON; n = 20) or the basal diet supplemented with 9g/steer/d of PRO feed additive (PRO; n = 20). The PRO additive is a blend of S. cerevisiae and the fermentation products of Enterococcus faecium, Bacillus licheniformis, B. subtilis, Lactobacillus animalis, and Propionibacterium freudenreichii. The DMI and water consumed were monitored using the GrowSafe intake nodes and custom flow meters, respectively. BWs were recorded weekly to calculate average daily gain (ADG). Before morning feeding, 10mL of blood was taken from each steer on days 0-7, and thereafter weekly for analyses of immune cells, plasma glucose, and NEFAs. On day 56, rumen fluid samples (200mL each) were collected from all the steers for microbiome analysis. Over the 56-d receiving period, the supplemental PRO had no effects on DMI, water intake, or ADG. However, compared to CON, beef steers fed supplemental PRO tended to have greater ADG (P = 0.08) and BW (P = 0.07) during the first 14 d of the study. There was a treatment × day interaction (P ≤ 0.05) for WBC, neutrophils and monocytes over the 56 d such that beef steers fed supplemental PRO had lower blood concentrations on certain days during the first 7 d after weaning, indicating reduced inflammation or stress response. The results of the rumen microbiome analysis revealed that the relative abundance of complex fiber degrading or obligate proton-reducing bacterial genera such as Bacteroides, Ruminococcus gauvreauii group, Desulfovibrio, Syntrophococcus, and Acetitomaculum were greater (P ≤ 0.05) in beef steers fed supplemental PRO compared to CON. This study demonstrated that dietary supplementation of PRO improved the growth performance, reduced stress or inflammatory response during the initial days after weaning, and altered the ruminal bacterial community toward increased relative abundance of bacterial genera associated with improved rumen function.

Metagenomic Insights into the Taxonomic and Functional Features of Traditional Fermented Milk Products from Russia.

Fermented milk products (FMPs) contain probiotics that are live bacteria considered to be beneficial to human health due to the production of various bioactive molecules. In this study, nine artisanal FMPs (kefir, ayran, khurunga, shubat, two cottage cheeses, bryndza, khuruud and suluguni-like cheese) from different regions of Russia were characterized using metagenomics. A metagenomic sequencing of ayran, khurunga, shubat, khuruud and suluguni-like cheese was performed for the first time. The taxonomic profiling of metagenomic reads revealed that Lactococcus species, such as Lc. lactis and Lc. cremoris prevailed in khuruud, bryndza, one sample of cottage cheese and khurunga. The latter one together with suluguni-like cheese microbiome was dominated by bacteria, affiliated to Lactobacillus helveticus (32-35%). In addition, a high proportion of sequences belonging to the genera Lactobacillus, Lactococcus and Streptococcus but not classified at the species level were found in the suluguni-like cheese. Lactobacillus delbrueckii, as well as Streptococcus thermophilus constituted the majority in another cottage cheese, kefir and ayran metagenomes. The microbiome of shubat, produced from camel's milk, was significantly distinctive, and Lentilactobacillus kefiri, Lactobacillus kefiranofaciens and Bifidobacterium mongoliense represented the dominant components (42, 7.4 and 5.6%, respectively). In total, 78 metagenome-assembled genomes with a completeness ≥ 50.2% and a contamination ≤ 8.5% were recovered: 61 genomes were assigned to the Enterococcaceae, Lactobacillaceae and Streptococcaceae families (the Lactobacillales order within Firmicutes), 4 to Bifidobacteriaceae (the Actinobacteriota phylum) and 2 to Acetobacteraceae (the Proteobacteria phylum). A metagenomic analysis revealed numerous genes, from 161 to 1301 in different products, encoding glycoside hydrolases and glycosyltransferases predicted to participate in lactose, alpha-glucans and peptidoglycan hydrolysis as well as exopolysaccharides synthesis. A large number of secondary metabolite biosynthetic gene clusters, such as lanthipeptides, unclassified bacteriocins, nonribosomal peptides and polyketide synthases were also detected. Finally, the genes involved in the synthesis of bioactive compounds like β-lactones, terpenes and furans, nontypical for fermented milk products, were also found. The metagenomes of kefir, ayran and shubat was shown to contain either no or a very low count of antibiotic resistance genes. Altogether, our results show that traditional indigenous fermented products are a promising source of novel probiotic bacteria with beneficial properties for medical and food industries.

MICROBIOME MODULATORS IN THE PREVENTION AND MITIGATION OF CANCER TREATMENT-INDUCED ACCELERATED AGING BIOLOGY

Abstract Advancements in oncology research have led to increased survivorship in patients with cancer. However, cancer treatments like chemotherapy cause debilitating side effects including multi-organ dysfunction and increased risk for chronic diseases, which mimic accelerated aging. Abnormalities in the gut microbiome composition (dysbiosis) increase inflammation, resulting in accelerated cognitive impairment with aging and a poor quality of life (QOL), which are all exacerbated by cancer treatments. We have screened, evaluated, and optimized our previously isolated human-origin live bacteria (probiotics) as well as pasteurized probiotics (postbiotics) for their anti-aging potential using Caenorhabditis (C.) elegans and mouse models. Probiotics improved the healthspan in C. elegans when given live and when fermented. Interestingly, PFM and LpD3.5 significantly protected from body weight loss, microbiome dysbiosis, and cognitive impairment in mice receiving 5-fluorouracil chemotherapy and protected from intestinal damage. We are planning a clinical trial where we will (1) cross-sectionally analyze the gut microbiome, leaky gut, and inflammation in cancer survivors with and without brain distress and (2) determine the safety, tolerance, and efficacy of PFM and LpD3.5 on microbiome diversity, inflammation, and cognitive health in cancer survivors with brain distress, using a 60-day open-label, randomized comparison study. These studies will improve our understanding of how cancer treatment-induced changes in the gut microbiome, inflammation, and gut permeability contribute to accelerated aging. Furthermore, they will establish the utilization of probiotics and postbiotics to improve QOL and mitigate cancer treatment-induced accelerated aging, which constitutes a debilitating public health concern among the increasing population of cancer survivors.

Prospects for using flow cytometry in the quality control of live plague vaccines

Scientific relevance. The number of live bacteria is a quality parameter controlled at all stages of live plague vaccine production. Currently, live microbial cell counting uses a bacteriological method. However, flow cytometry has the potential to increase analytical accuracy and reduce testing time.Aim. This study aimed at testing the applicability of flow cytometry to assessing the quality of live plague vaccines.Materials and methods. The study quantified live microbial cells in 5 experimental batches of live plague vaccine as part of their quality control using the bacteriological method according to the State Pharmacopoeia of the Russian Federation (FS.3.3.1.0022.15). Cytofluorometry of the samples used the SynaptoGreen fluorescent dye.Results. The study quantified live microbial cells in live plague vaccine samples using the bacteriological method and flow cytometry. The results obtained by the bacteriological method ranged from 27.8±2.2 to 56.5±3.1% with an average of 39.8±5.4%. The results obtained by flow cytometry ranged from 29.2±1.2 to 59.1±2.1% with an average of 41.7±5.5%. The statistical analysis showed no significant difference between the results of vaccine quality control by both methods, as well as a high coefficient of determination.Conclusions. The results show that flow cytometry is an appropriate method for the quantification of live microbial cells as part of the quality control of plague vaccines. Being quick, easy, and highly informative, flow cytometry is preferable to traditional methods.

Staphylococcus aureus functional amyloids catalyze degradation of β-lactam antibiotics

Antibiotic resistance of bacteria is considered one of the most alarming developments in modern medicine. While varied pathways for bacteria acquiring antibiotic resistance have been identified, there still are open questions concerning the mechanisms underlying resistance. Here, we show that alpha phenol-soluble modulins (PSMαs), functional bacterial amyloids secreted by Staphylococcus aureus, catalyze hydrolysis of β-lactams, a prominent class of antibiotic compounds. Specifically, we show that PSMα2 and, particularly, PSMα3 catalyze hydrolysis of the amide-like bond of the four membered β-lactam ring of nitrocefin, an antibiotic β-lactam surrogate. Examination of the catalytic activities of several PSMα3 variants allowed mapping of the active sites on the amyloid fibrils’ surface, specifically underscoring the key roles of the cross-α fibril organization, and the combined electrostatic and nucleophilic functions of the lysine arrays. Molecular dynamics simulations further illuminate the structural features of β-lactam association upon the fibril surface. Complementary experimental data underscore the generality of the functional amyloid-mediated catalytic phenomenon, demonstrating hydrolysis of clinically employed β-lactams by PSMα3 fibrils, and illustrating antibiotic degradation in actual S. aureus biofilms and live bacteria environments. Overall, this study unveils functional amyloids as catalytic agents inducing degradation of β-lactam antibiotics, underlying possible antibiotic resistance mechanisms associated with bacterial biofilms.

Characterization of Lactococcus lactis 11/19-B1 Isolated from Kiwi Fruit as a Potential Probiotic and Paraprobiotic.

Probiotics are live bacteria used as food additives that are beneficial to human health. Lactococcus lactis 11/19-B1 strain isolated from kiwi fruit stimulates innate immunity in silkworms. Intake of yogurt containing the living 11/19-B1 strain significantly decreases the level of low-density lipoproteins (LDLs) in high-LDL volunteers and improves atopic dermatitis in humans. In this study, the probiotic properties of the 11/19-B1 strain, such as sensitivity to antimicrobial compounds, biogenic amine production, some virulence genes for human health, antimicrobial activity, tolerance to gastric acid and bile acids, and ability to adhere to the intestinal mucosa, were evaluated. The 11/19-B1 strain did not show resistance to the tested antimicrobial compounds except cefoxitin and fosfomycin. In addition, no production of amines that can harm humans, the antimicrobial activity required for probiotics, and the absence of adhesion to Caco-2 cells suggest that it is unlikely to attach to the intestinal epithelium. The 11/19-B1 strain grew in 0.3% but not in 1% bile salt. In the presence of 2% skim milk, the survival rate of the 11/19-B1 strain under simulated gastrointestinal tract conditions was 67% even after 4 h. These results indicate that the 11/19-B1 strain may function as a probiotic or paraprobiotic to be utilized in the food industry.

Screening of anti-allergic Lactiplantibacillus species by splenocyte sensitization model and evaluate their probiotic and postbiotic characteristics

Lactiplantibacillus species has garnered considerable attention due to its multifaceted probiotic properties, particularly its potential in alleviating food allergies. Despite numerous reports supporting this claim, scant research exists concerning the methodology for screening anti-allergic probiotics. Thus study sought to establish an in vitro splenocyte sensitization model for the purpose of screening potential anti-allergic Lactiplantibacillus strains. Through the splenocyte model, different Lactiplantibacillus strains were assessed for their ability to modulate the Th1/Th2 balance in sensitized splenocytes. The results showed that compared with the of positive control (IFN-γ/IL-4 value was 1.12) and LGG (IFN-γ/IL-4 value was 15.88), Lactiplantibacillus XJ 002, TLF 1-2 and TLF 5-3-2 had the greatest effect on improving IFN-γ/IL-4 value, which were 9.89, 15.81 and 9.72 respectively. The further results showed that the IL-10 levels of Lactiplantibacillus XJ 002, TLF 1-2 and TLF 5-3-2 reached 125.23, 147.44 and 113.16 ng/L, which were significantly higher than the positive control (84.95 ng/L, p < 0.05). Moreover, the IgE reduction rates of Lactiplantibacillus XJ 002, TLF 1-2 and TLF 5-3-2 were 82%, 72% and 40% respectively, which indicated that Lactiplantibacillus XJ 002 and TLF 1-2 showed the best regulatory ability. Subsequently, Lactiplantibacillus XJ 002 and TLF 1-2 were considered promising probiotic candidates following rigorous probiotic evaluation. Remarkably, the inactivated forms of these strains, functioning as postbiotics, exhibited similar anti-allergic effects to those of the live bacteria. Consequently, this study not only offers valuable insights into the screening of anti-allergic probiotics but also explores the potential applications of postbiotics.

PH-dependent pressure-sensitive colonic capsules for the delivery of aqueous bacterial suspensions

Microbiome-based therapies hold great promise for treating various diseases, but the efficient delivery of live bacteria to the colon remains a challenge. Furthermore, current oral formulations, such as lyophilized bacterial capsules or tablets, are produced using processes that can decrease bacterial viability. Consequently, high dosages are required to achieve efficacy. Herein, we report the design of pressure-sensitive colonic capsules for the encapsulation and delivery of aqueous suspensions of live bacteria. The capsules consisted of 2 functional thin-films (hydrophobic and enteric) of ethyl cellulose and Eudragit S100 dip-coated onto hydroxypropyl methylcellulose molds. The capsules could be loaded with aqueous media and provide protection against acidic fluids and, to some extent, oxygen diffusion, suggesting their potential suitability for delivering anaerobic bacterial strains. Disintegration and mechanical studies indicated that the capsules could withstand transit through the stomach and upper/proximal small intestinal segments and rupture in the ileum/colon. In vitro studies showed that bacterial cells (anaerobic and aerobic commensals) remained highly viable (74–98%) after encapsulation and exposure to the simulated GI tract conditions. In vivo studies with a beagle dog model revealed that 67% of the capsules opened after 3.5 h, indicating content release in the distal gastrointestinal tract. These data demonstrate that live aqueous bacterial suspensions comprised of both aerobic and anaerobic commensals can be encapsulated and in the future might be efficiently delivered to the distal gastrointestinal tract, suggesting the practical applications of these capsules in microbiome-based therapies.

Rapid screening of electrochemically active bacteria based on a biocathode-functional bipolar electrode-electrochemiluminescence platform.

A functional bipolar electrode-electrochemiluminescence (BPE-ECL) platform based on biocathode reducing oxygen was constructed for detecting electrochemically active bacteria (EAB) in this paper. Firstly, thiolated trimethylated chitosan quaternary ammonium salt (TMC-SH) layer was assembled on the gold-plated cathode of BPE. TMC-SH contains quaternary ammonium salt branch chain, which can inhibit the growth of microorganisms on the surface or in the surrounding environment while absorbing bacteria. Then, the peristaltic pump was used to flow all of the samples through the cathode, and the EAB was electrostatically adsorbed on the electrode surface. Finally, applying a constant potential to the BPE, bacteria can catalyze electrochemical reduction of O2, and decrease the overpotential of O2 reduction at the cathode, which in turn generates an ECL reporting intensity change at the anode. In this way, live and dead bacteria can be distinguished, and the influence of complex food substrates on detection can be greatly reduced.

Moisture evaporation effect on pore structure and microbial distribution during sludge biodrying

Biodrying of dewatered sludge is an eco-friendly and efficient technology to decrease the sludge moisture content (MC) by metabolic heat generated from sludge organic matter degradation. By analyzing the water states and visualizing the sludge pore structure during the biodrying process, it was found that the bound water accounted for 96.5–97.9% of the sludge water and interstitial water was only 2.0–3.5%. The microscopic and dispersed sludge pores were transformed into larger and linked ones by the transformation of bound water into interstitial water and the subsequent evaporation. As a result, the depth of live bacteria distribution thickened, reaching 0–180 µm, 0–330 µm, and 0–350 µm during the temperature ramp-up to 45.6 °C, the peak temperature of 70.7 °C, and the cool-down to 45.6 °C, respectively. Briefly, as moisture evaporated, the pore structure of the sludge expanded and the microbial distribution deepened. Moreover, the phylum of anaerobic bacteria was drastically decreased.

Effect of Buffalo Curd Milk-Edamame Pudding Snack Consumption on Fasting Blood Glucose Levels and Lipid Profile in Diabetes Mellitus Patients

Background: Buffalo milk curd, a native probiotic source from Indonesia, is dominated by live indigenous Lactic Acid Bacteria known for their ability to lower blood glucose levels. Edamame contains amino acid arginine, chromium, antioxidants, and fibre, aiding in blood glucose control and lipid profile reduction. Objectives: This study aimed to assess the effects of buffalo milk curd and edamame-based pudding snacks on fasting blood glucose levels and lipid profiles in Type 2 diabetes mellitus (T2DM) patients. Methods: This study used a True Experiment Design with Pretest-Posttest Control Group Design. The study involved 32 patients divided into treatment and control groups. During the study, the treatment group received 250 g of snacks in the morning and evening for one week. Blood glucose levels and lipid profiles were measured using the enzymatic colourimetry method. Results: The results showed decreased fasting blood glucose levels before and after treatment in both control (-17.06 ± 40.17) and treatment (-48.38 ± 40.27 mg/dl) groups (p=0.036). Total cholesterol levels also decreased in control (-15.87 ± 23) and treatment (-41.4 ± 19 mg/dl) groups (p=0.001). There were decreased LDL levels in control (-6.81 ± 29.09) and treatment (-27.3 ± 25.09 mg/dl) groups (p=0.04). However, HDL and TG levels showed no differences at the end of the study. Conclusions: Buffalo curd milk-edamame pudding snacks can reduce fasting blood glucose levels and lipid profiles, particularly total cholesterol and LDL levels, in Type 2 DM patients.

Development of Methods to Obtain Composite Materials from Organoclays

The paper presents methods to obtain a bionanocomposite from hydrophobic halloysite with bacteridic properties. During the study using TEM analysis, it was established that Karaganda halloysite has a natural nanostructured material and has a cylindrical in shape (halloysite nanotube HNT). It was shown that bactericidal properties of nanoclays are due to exchange reactions between Ag+ and with active groups of nanoclay, where free H+ ions are present. The presence of several peaks characteristic of silver was detected by energydispersive X-ray spectroscopy, indicating exchange reactions involving silver. The bactericidal properties of silver-modified halloysite were proven using in situ analysis with live bacteria. The observed displacements of interlayer spaces from values of 9.997 Å to 17.51 Å in the diffraction patterns confirmed the successful intercalation of octadecylamine into the nanohalloisite galleries. Such medicinal bionanocomposite materials can be used as carriers of various vitamins and drugs due to their high adsorption properties. A study to obtain bactericidal oleophilic (hydrophobic) bionanocomposites based on Karaganda halloysite was carried out for the first time and it includes the stages of processing halloysite with silver ions and the stage of hydrophobization of bactericidal halloysite.

Quantifying picomoles of analyte from less than 100 live bacteria: A novel method with a buffering hydrogel as an electrochemical cell

Microenvironmental changes in the chemical surrounding of bacterial cells might have a profound impact on the ecology of biofilms. However, quantifying total amount of picomoles of analyte from a miniscule number of bacteria is an analytical challenge. Here we provide a novel microliter volume hydrogel based electrochemical cell platform suitable of coulometrically measuring hydrogen peroxide (H2O2) produced by less than 100 cells of Streptococcus sanguinis, a relevant member of the healthy oral microbiome. A morpholine moiety was incorporated into the polymer structure of the hydrogel to create a controlled microenvironment at biological pH. We calculated the buffering capacity of this hydrogel as 0.257 ± 0.135 molHNO3molMEA×ΔpHover the pH range of 7.2–6.2 by using a novel method designed for buffering hydrogels. The H2O2 sensors coated in microliter volume of buffering hydrogel showed no change in sensitivity within the pH range of 7.0–3.0, allowing for H2O2 measurements of S. sanguinis independent of any acid they produce. The novel platform was able to measure down to 22.7 ± 3.5 pmol H2O2 produced by less than 100 bacterial cells, which would otherwise not be attainable in large solution-based assays. These findings indicate that this is a suitable platform for quantifying metabolites from sub-milligram biological samples and may even be suitable for direct analysis of raw biofilms samples with little to no sample pretreatment.

A Biochemical Corrosion Monitoring Sensor with a Silver/Carbon Comb Structure for the Detection of Living Escherichia coli.

For the detection and monitoring of live bacteria, we propose a biochemical corrosion monitoring (BCM) sensor that measures galvanic current by using a Ag/C sensor comprising silver and carbon comb electrodes. The deposition of an Escherichia coli suspension containing an LB liquid medium on the Ag/C sensor increased the galvanic current. The time required for the current to reach 20 nA is defined as T20. T20 tends to decrease as the initial number of E. coli in the E. coli solution increases. A linear relationship was obtained between the logarithm of the E. coli count and T20 in a bacterial count range of 1-108 cfu/mL under culture conditions in which the growth rate of the bacteria was constant. Hence, the number of live E. coli could be determined from T20. Ag2S precipitation was observed on the surface of the Ag electrode of the Ag/C sensor, where an increase in the current was observed. This generation of galvanic current was attributed to the reaction between a small amount of free H2S metabolized by E. coli in the bacterial solution during its growth process and Ag-the sensor anode. The Ag/C sensor can detect a free H2S concentration of 0.041 μM in the E. coli solution. This novel biochemical sensor can monitor the growth behavior of living organisms without damaging them.

A Novel Co-Culture Model Reveals Enhanced CFTR Rescue in Primary Cystic Fibrosis Airway Epithelial Cultures with Persistent Pseudomonas aeruginosa Infection.

People with cystic fibrosis (pwCF) suffer from chronic and recurring bacterial lung infections that begin very early in life and contribute to progressive lung failure. CF is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, which encodes an ion channel important for maintaining the proper hydration of pulmonary surfaces. When CFTR function is ablated or impaired, airways develop thickened, adherent mucus that contributes to a vicious cycle of infection and inflammation. Therapeutics for pwCF, called CFTR modulators, target the CFTR defect directly, restoring airway surface hydration and mucociliary clearance. However, even with CFTR modulator therapy, bacterial infections persist. To develop a relevant model of diseased airway epithelium, we established a primary human airway epithelium culture system with persistent Pseudomonas aeruginosa infection. We used this model to examine the effects of CFTR modulators on CFTR maturation, CFTR function, and bacterial persistence. We found that the presence of P. aeruginosa increased CFTR mRNA, protein, and function. We also found that CFTR modulators caused a decrease in P. aeruginosa burden. These results demonstrate the importance of including live bacteria to accurately model the CF lung, and that understanding the effects of infection on CFTR rescue by CFTR modulators is critical to evaluating and optimizing drug therapies for all pwCF.

The effect of a microbiological product based on &lt;i&gt;Lactobacillus buchneri&lt;/i&gt; on barley growth and productivity in the Vologda region

The purpose of the work was to study the effect of the experimental microbiological product ‘Naturost-Aktiv’, developed on the basis of live bacteria Lactobacillus buchneri, on barley growth and productivity in the Vologda region. The study was carried out during the vegetation periods of 2019, 2020 and 2022 on the experimental field of the FSBIS «Vologda Research Center of the Russian Academy of Sciences», as well as in production conditions on the fields of the APC Collective farm «Peredovoy» (Vologda Region). The product ‘Naturost-Aktiv’ was applied twice, when the seeds of the experimental group were soaked in the working solution (1 ml of the product per 1 liter of water) and the phyllosphere of the plants was sprayed in the tillering phase. Tap water was used as control. As a result, there has been identified an increase in the potential energy supply of barley. The area of an individual leaf of experimental plants exceeded the control by 16 %, and the content of the total chlorophylls (a+b) exceeded by 34–42 %, which contributed to a more active accumulation of dry mass of experimental plants in comparison with the control (duringthe action of the product there was an increase in the dry weight of the plant by 12–65 % relative to the control). The changes in the plant growth processes also affected the grain productivity, which increased by 8–26 % in the variants with the product compared to the control. The results of the production experiment, in general, turned out to be like the results of small-plot experiments. Thus, in the conditions of real management, grain productivity of the barley variety ‘Sonet’ increased by 14 % with the use of the product ‘Naturost-Aktiv’ relative to the control. Grain productivity improvement was associated both with an increase in the number of productive shoots and with an increase in the weight of an individual grain.

Bioaerosol Sensor for In Situ Measurement: Real-Time Measurement of Bioaerosol Particles in a Real Environment and Demonstration of the Effectiveness of Air Purifiers to Reduce Bioaerosol Particle Concentrations at Hot Spots

In this study, we first conducted laboratory experiments on the sensitivity of a newly developed bioaerosol sensor (BAS) suitable for in situ measurements. Then, we performed an in situ test in a shared student space at a university. Furthermore, the effectiveness of ventilation and air purification as a mitigation measure for a location with high concentrations of bioaerosol particles (hot spots) was verified. The experimental results show that the measured values for polystyrene latex are in good agreement with the predicted Mie theory value. They also show a good response to fluorescent particles. The in situ test showed that the BAS fluorescent system does not respond to non-fluorescent particles but only to fluorescent particles. During respiratory infection outbreaks, real-time detection at hot spots and a reduction in particulate matter, including bioaerosols, through ventilation and air purification equipment are effective. In this study, the BAS measurement results showed significant correlations not only with fluorescent particles but also with live bacteria. This does not prove that viruses can be measured in real time. If real-time measurements for viruses become available in the future, the findings of this study will be helpful in mitigating respiratory tract infections caused by viruses.

Bacteria debridement efficacy of two sonic root canal irrigant activation systems

ObjectiveTo evaluate the bacteria debridement efficacy of two generations of sonic root canal irrigant activation systems: EndoActivator (Dentsply Sirona), the first generation, and SmartLite Pro EndoActivator, the second generation. MethodsInstrumented, autoclaved, single-rooted human premolars were inoculated with Enterococcus faecalis (ATCC-29212) for 21 days. The bacteria biofilm-containing teeth were randomly divided into 5 groups (N=8): Group 1: Syringe-side-vented needle (S-N) delivery of saline for 1 min; Group 2: S-N delivery of 2% NaOCl for 1 min; Group 3: S-N delivery of 2% NaOCl for 5 min; Group 4: EndoActivator activation of 2% NaOCl for 1 min; Group 5: SmartLite Pro EndoActivator activation of 2% NaOCl for 1 min. The teeth were evaluated for bacterial reduction using CFU counts, and the percentages of dead bacteria within the dentinal tubules using confocal laser scanning microscopy. ResultsActivation of NaOCl with EndoActivator or SmartLite Pro EndoActivator significantly reduced the overall intracanal bacterial load, compared with S-N irrigant delivery (P<0.05), with no significant difference between the two agitation devices (P>0.05). Nevertheless, S-N delivery of 2% NaOCl for 5 min produced better bacteria debridement than either sonic agitation system. Different degrees of bacteria kill were identified in the coronal-middle portions and apical portion of the canal space. ConclusionDelivery time of NaOCl affects the efficacy of bacteria disinfection. Activation for 1 min with the EndoActivator or SmartLite Pro EndoActivator demonstrated comparable canal wall biofilm and intracanal bacteria reduction efficacy when 2% NaOCl was used as irrigant for disinfecting E. faecalis in single-rooted teeth. Clinical significanceAlthough the sonic root canal irrigant activation devices investigated do not completely eliminate live bacteria biofilms from the canal space, they help reduce bacteria load during irrigant activation.

Development of PMA-qPCR assay to accurately and reproducible quantify viable bacteria of Paenibacillus polymyxa.

Paenibacillus polymyxa is an important biocontrol bacterium. The combination of propidium monoazide (PMA) and quantitative polymerase chain reactionq (qPCR) has proven effective in quantifying live bacteria from various microorganisms. The objective was to create a PMA-qPCR assay to precisely and consistently measure the number of living bacteria of biocontrol P. polymyxa. The primers were designed for the spo0A gene of P. polymyxa HY96-2. The optimal conditions for treating the target strain with PMA were a PMA concentration of 15 μg/mL, an incubation time of 5 min, and an exposure time of 10 min. The PMA-qPCR method had a limit of quantification (LOQ) of 1.0×103 CFU/mL for measuring the amount of viable P. polymyxa bacteria. The PMA-qPCR method is more sensitive than the qPCR method in detecting viable bacteria in the mixtures of viable and dead bacteria. The accuracy and reproducibility of quantifying viable P. polymyxa bacteria using the PMA-qPCR method were higher compared to the plate count method.

Studying the influence of guava fruitghurt on Escherichia coli coloniesin rats’ digestive tracts

A balanced microbiota can play a role in the host's defense mechanism against pathogenic infections. E. coli is a harmless and beneficial commensal. An increase in bacteria will change their nature to become pathogens that can cause gastrointestinal disease, such as diarrhea. The management of such condition can be managed in several ways, including the consumption of probiotics. Fruitghurt is a variant of yogurt that is made using fruit juice. L. acidophilus is resistant to stomach acid; it can inhibit the growth of pathogenic bacteria and can maintain the number of live bacteria up to 107/ml. The research design used was experimental. The research subjects were white rats (Rattus norvegicus), with the Wistar strain as many as 27 rats. They were divided into 3 groups: 1. K (-),a negative control group that was not induced by E. coli and was not given fruitghurt; 2. K (+)a positive control group that was given E.coli, but not treated by fruitghurt; and 3. P1, the treatment group that was induced with E.coli and treated by fruitghurt. The results showed that guava fruitghurt could reduce E. coli colonies. The number of E. coli colonies after being given fruitghurt was 161, while in the rats that were not given fruitghurt, there were 258 colonies. Guava fruitghurt can reduce E. coli because of the flavonoid, tannin, and polyphenol contents found in red guava, which act as protein coagulators, antibacterials, and toxins, as well as L. acidophilus bacteria that can inhibit the growth and attachment of pathogenic bacteria in the digestive tract and inhibit the spread of pathogenic bacteria.