Number Of Live Bacteria Research Articles

Optimal ultrasonic treatment frequency and duration parameters were used to detect the pathogenic bacteria of orthopedic implant-associated infection by ultrasonic oscillation

IntruductonThe most accurate method for detecting the pathogen of orthopedic implant-associated infections (OIAIs) is sonication fluid (SF). However, the frequency and duration of ultrasound significantly influence the number and activity of microorganisms. Currently, there is no consensus on the selection of these two parameters. Through this study, the choice of these two parameters is clarified. MethodsWe established five ultrasonic groups (40kHz/10min, 40kHz/5min, 40 kHz/1min, 20kHz/5min, and 10kHz/5min) based on previous literature. OIAIs models were then developed and applied to ultrasound group treatment. Subsequently, we evaluated the efficiency of bacteria removal by conducting SEM and crystal violet staining. The number of live bacteria in the SF was determined using plate colony count and live/dead bacteria staining. ResultsThe results of crystal violet staining revealed that both the 40kHz/5min group and the 40kHz/10min group exhibited a significantly higher bacterial clearance rate compared to the other groups. However, there was no significant difference between the two groups. Additionally, the results of plate colony count and fluorescence staining of live and dead bacteria indicated that the number of live bacteria in the 40kHz/5min SF group was significantly higher than in the other groups. Conclusion40kHz/5min ultrasound is the most beneficial for the detection of pathogenic bacteria on the surface of orthopedic implants.

Oleanolic Acid Promotes the Formation of Probiotic Escherichia coli Nissle 1917 (EcN) Biofilm by Inhibiting Bacterial Motility.

Probiotic biofilms have been beneficial in the fight against infections, restoring the equilibrium of the host's gut microbiota, and enhancing host health. They are considered a novel strategy for probiotic gut colonization. In this case, we evaluated the effects of various active substances from traditional Chinese medicine on Escherichia coli Nissle 1917 (EcN) to determine if they promote biofilm formation. It was shown that 8-64 μg/mL of oleanolic acid increased the development of EcN biofilm. Additionally, we observed that oleanolic acid can effectively suppress biofilm formation in pathogenic bacteria such as Salmonella and Staphylococcus aureus. Next, we assessed the amount of EcN extracellular polysaccharides, the number of live bacteria, their metabolic activity, the hydrophobicity of their surface, and the shape of their biofilms using laser confocal microscopy. Through transcriptome analysis, a total of 349 differentially expressed genes were identified, comprising 134 upregulated and 215 downregulated genes. GO functional enrichment analysis and KEGG pathway enrichment analysis revealed that oleanolic acid functions are through the regulation of bacterial motility, the iron absorption system, the two-component system, and adhesion pathways. These findings suggest that the main effects of oleanolic acid are to prevent bacterial motility, increase initial adhesion, and encourage the development of EcN biofilms. In addition, oleanolic acid interacts with iron absorption to cooperatively control the production of EcN biofilms within an optimal concentration range. Taking these results together, this study suggests that oleanolic acid may enhance probiotic biofilm formation in the intestines, presenting new avenues for probiotic product development.

Effect of microbubble as local drug delivery system in endodontic management - An In-Vitro study

Background and ObjectivesMicrobubbles (MBs) are gas or vapor-filled cavities inside liquids with sizes ranging from 2 to 3 µm. Recently, MBs have shown great promise in nanomedicine owing to their high encapsulation efficiency, targeted drug release, improved biocompatibility, and longer blood circulation. Furthermore, they are more suitable for focusing on particular body regions and are safer and non-invasive. MBs generators are used to create bubbles in fluid dynamics, chemistry, medicine, agriculture, and the environment. Drug delivery using MBs increases penetration without causing systemic toxicity.In this study, we examined whether the use of microbubbles as a local drug-delivery mechanism increases tubular penetration of endodontic medications and irrigant. Materials and MethodsAn Enterococcus faecalis culture was added to 38 dentin cylinders of single-rooted teeth. Samples were divided into the experimental and control groups that received a triple antibiotic paste with and without MB infusion (n = 19 in each group), respectively. After 14 days, the number of live bacteria in the samples was determined using confocal laser scanning microscopy. ResultsAfter 14 days of contact with the medication, the percentages of live and dead bacteria were assessed. Results show that Group 2 (Triple antibiotic infused micro bubble) showed significantly (P < 0.05) higher antibacterial efficacy than Group 1 (TAP). ConclusionIn this study, the antibacterial efficacy was significantly higher in the experimental group than in the control group. Therefore, within the limitations of the study it can be said that MB infusion is a viable technique to improve root canal disinfection. Hence, it can be considered as a novel technique for local drug delivery systems in endodontic management.

Effect of Different Air Oven Temperatures on Chemical, Physical, and Microbial Properties of Dried Bio-Yoghurt Product

The aim of this study was to compare the physical, chemical, and microbiological features of bio-yoghurt that had been air-oven-dried at three temperatures (40, 50, and 60 °C) to those of fresh bio-yoghurt. The results showed that drying bio-yoghurt at 40–60 °C decreased the number of probiotic starter bacteria in dried yoghurt products compared to fresh bio-yoghurt. The dried yoghurt’s moisture, protein, fat, carbohydrate, and ash contents were 4.16–4.55%, 38.22–40.02%, 1.33–1.43%, 47.94–49.45%, and 6.37–6.55%, respectively. The pH and total acidity levels of dried yoghurt were within acceptable ranges at various temperatures and storage durations. At different temperatures, the viscosity values of the products decreased by 620–550 cp; however, the hygroscopicity values remained constant. During a 90-day storage period, the dried yoghurt product’s physical, chemical, and microbiological characteristics remained within acceptable levels. Using a drying temperature of 40–50 °C kept the number of live bacteria below acceptable ranges during storage periods. Lactobacillus acidophilus counts were 6.75 and 6.70 log CFU/g, respectively, whereas Bifidobacterium bifidum numbers were 6.66 and 6.08 log CFU/g, respectively. In conclusion, drying bio-yoghurt in an air oven at 40–50 °C provided a dried product with a high number of viable probiotic bacteria and satisfactory physicochemical characteristics after 3 months.

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.

Antibacterial Activity of a Lysin LysP53 against Streptococcus mutans.

Dental caries is a common disease affecting quality of life globally. In the present study, we found that a bacteriophage lysin LysP53 against Acinetobacter baumannii possesses selective activity on Streptococcus mutans, the main etiological agent of dental caries, even in low pH caries microenvironments, whereas only minor LysP53 activity was detected against Streptococcus sanguinis, Streptococcus oralis, and Streptococcus mitis. Testing activity against S. mutans planktonic cells showed that 4 μM LysP53 could kill more than 84% of S. mutans within 1 min in buffer with optimal pHs ranging from 4.0 to 6.5. Daily application of LysP53 on biofilms formed in BHI medium supplemented or not with sucrose could reduce exopolysaccharides, expression of genes related to acid resistance and adhesion, and the number of live bacteria in the biofilms. LysP53 treatment also showed similar effects as 0.12% chlorhexidine in preventing enamel demineralization due to S. mutans biofilms, as well as effective removal of S. mutans colonization of tooth surfaces in mice without observed toxic effects. Because of its selective activity against main cariogenic bacteria and good activity in low pH caries microenvironments, it is advantageous to use LysP53 as an active agent for preventing caries.

Biofilm Removal from In Vitro Narrow Geometries Using Single and Dual Pulse Er:YAG Laser Photoacoustic Irrigation.

The disinfection and removal of biofilm from titanium dental implants remains a great challenge in oral medicine. Here we present results of novel photoacoustic irrigation laser modalities for biofilm removal in model geometries mimicking the peri-implant pocket. The efficacy of single pulse (Er:YAG-SSP) and dual pulse (Er:YAG-AutoSWEEPS) photoacoustic irrigation modalities were determined for Enterococcus faecalis biofilm decontamination from titanium surfaces in narrow cylindrical and square gap geometries. The density of bacteria as well as the number of live bacteria were determined prior and after different photoacoustic treatments. Both SSP and AutoSWEEPS photoacoustic irrigation techniques removed at least 92% of biofilm bacteria during the 10 s photoacoustic treatment. The effectiveness of cleaning was better in the narrow square gap geometry compared to the cylindrical geometry. The dual pulse Er:YAG-AutoSWEEPS photoacoustic irrigation showed better results compared to SSP modality. No chemical adjuvants were needed to boost the effectiveness of the photoacoustic irrigation in the saline solution. The results imply that photoacoustic irrigation is an efficient cleaning method for debridement and decontamination in narrow geometries and should be considered as a new therapeutic option for the treatment of peri-implant diseases.

Metabolomics and molecular docking analysis of antibiotic exposure in Bifidobacterium adolescentis.

Bifidobacterium adolescentis is a probiotic. This research aimed to investigate the mechanism of antibiotics led to decrease in the number of B. adolescentis. The metabolomics approach was employed to explore the effects of amoxicillin on metabolism of B.adolescentis, while MTT assay and scanning electron microscopy were applied to analyse changes in viability and morphology of bacteria. Molecular docking was used to illuminate the mechanism by which amoxicillin acts on a complex molecular network. The results showed that increasing the concentration of amoxicillin led to a gradual decrease in the number of live bacteria. Untargeted metabolomics analysis identified 11 metabolites that change as a result of amoxicillin exposure. Many of these metabolites are involved in arginine and proline metabolism, glutathione metabolism, arginine biosynthesis, cysteine, and methionine metabolism, and tyrosine and phenylalanine metabolism. Molecular docking revealed that amoxicillin had a good binding effect on the proteins AGR1, ODC1, GPX1, GSH, MAT2A, and CBS. Overall, this research provides potential targets for screening probiotic regulatory factors and lays a theoretical foundation for the elucidation of its mechanisms.

Improvement of the Lyophilization Survival Rate of Lactobacillus casei via Regulation of Its Surface Substances.

The influence of surface substance production on the freeze-drying survival of Lactobacillus casei and methods to control the surface substances during fermentation were studied. The bacteria were treated with hypertonicity combined with ultrasound, and the survival rate was determined. The optimal conditions for removing surface substance without harming the bacteria were 81 w/18 min. The surface substances provided a protective effect on the lyophilization of the bacteria without protectants. However, in the presence of protectants, excessive surface substances reduced the protective effect of the optimum protectant alginate to 39.69 ± 1.27%. Finally, the amount of surface substances and lyophilized survival rate of collected bacteria were determined by adding EDTA during fermentation and regulating fermentation conditions, such as the carbon source, carbon-to-nitrogen ratio, and pH. The highest survival rate was 85.79 ± 3.29%, which was achieved when the amount of surface substances was (2.82 ± 0.55) × 10-11 mg/CFU. Therefore, the production of surface substances by the bacteria could be reduced by modifying the fermentation stage, which has significance in the improvement of the lyophilization survival rate of L. casei and the number of live bacteria per unit mass of L. casei in the lyophilized preparation.

Study on the pharmacodynamic activity of combinations with the new anti-tuberculosis drug pyrifazimine in vitro and in vivo in mouse

Objective: To evaluate two-drug combination interaction between pyrifazimine(TBI-166) and anti-drug-resistant tuberculosis group A drugs Bedaquiline (BDQ), Moxifloxacin (MFX) and the new anti-tuberculosis drug Delamanid (DLM), SQ109, Q203, and PBTZ169 in vitro and in vivo in mouse, so as to provide basis for TBI-166 combination therapy. Methods: This study was performed from September 2020 to July 2021. The chessboard method was used to evaluate the interaction between TBI-166 and BDQ, MFX, DLM, SQ109, and PBTZ169. The time-killing kinetics method was used to evaluate the anti-tuberculosis activity of the two-drug combination with partial synergy. The BALB/c mouse acute infection model was used to evaluate the anti-tuberculosis activity at 4 and 8 weeks in the two-drug combination group (TBI-166+BDQ, TBI-166+SQ109, TBI-166+PBTZ169, TBI-166+Q203) and monotherapy groups (TBI-166, BDQ, SQ109, PBTZ169, Q203). Data analysis was performed using an independent sample t-test. Results: After TBI-166 combined with anti-tuberculosis drugs, MIC was reduced to 6.25% to 25.00% of TBI-166 monotherapy. After TBI-166 combined with BDQ, SQ109 and PBTZ169, the partial inhibitory concentration index (FICI) values were 0.53, 0.75 and 0.75, respectively; the time sterilization experiment showed that the viable population of Mycobacterium tuberculosis treated with two-drug combination of TBI-166 and BDQ, SQ109, PBTZ169 for 14 days decreased at least 3 log10 CFU/ml. In the mouse experiments, it was found that, the amount of viable bacteria in lung tissue of BDQ, SQ109 and PBTZ169 combined with TBI-166 groups was lower than that of the monotherapy group,respectively. The lung tissue culture of mice in the TBI-166+BDQ group was negative after 4 weeks of treatment, and the number of live bacteria in the lungs of the TBI-166+BDQ group was 1.49 log10CFU lower than that of the BDQ monotherapy group(P<0.01). Conclusion: In vitro and in vivo experiments in mice revealed that TBI-166 had synergistic anti-tuberculosis activity after being combined with BDQ, SQ109 and PBTZ169, respectively.

Effect of nutritional and environmental conditions on biofilm formation of avian pathogenic Escherichia coli.

To study the effects of environmental stress and nutrient conditions on biofilm formation of avian pathogenic Escherichia coli (APEC). The APEC strain DE17 was used to study biofilm formation under various conditions of environmental stress (including different temperatures, pH, metal ions, and antibiotics) and nutrient conditions (Luria-Bertani [LB] and M9 media, with the addition of different carbohydrates, if necessary). The DE17 biofilm formation ability was strongest at 25°C in LB medium. Compared to incubation at 37°C, three biofilm-related genes (csgD, dgcC, and pfs) were significantly upregulated and two genes (flhC and flhD) were downregulated at 25°C, which resulted in decreased motility. However, biofilm formation was strongest in M9 medium supplemented with glucose at 37°C, and the number of live bacteria was the highest as determined by confocal laser scanning microscopy. The bacteria in the biofilm were surrounded by a thick extracellular matrix, and honeycomb-like or rough surfaces were observed by scanning electron microscopy. Moreover, biofilm formation of the DE17 strain was remarkably inhibited under acidic conditions, whereas neutral and alkaline conditions were more suitable for biofilm formation. Biofilm formation was also inhibited at specific concentrations of cations (Na+ , K+ , Ca2+ , and Mg2+ ) and antibiotics (ampicillin, chloramphenicol, kanamycin, and spectinomycin). The real-time quantitative reverse transcription PCR showed that the transcription levels of biofilm-related genes change under different environmental conditions. Nutritional and environmental factors played an important role in DE17 biofilm development. The transcription levels of biofilm-related genes changed under different environmental and nutrient conditions. The findings suggest that nutritional and environmental factors play an important role in APEC biofilm development. Depending on the different conditions involved in this study, it can serve as a guide to treating biofilm-related infections and to eliminating biofilms from the environment.

Nanoparticle-mediated delivery system alleviates the formation of infection stones by activating TRPV5.

Infection stones constitute a small but intractable group of diseases of urinary system. In this study, we explored the potential therapeutic effect of a small activation RNA, ds-320, encapsulated in chitosan (320-chitosan). Western blot analysis verified the downregulation of TRPV5 in patients and rat model of infection stones, as well as the stimulation of ds-320 on TRPV5 expression. MTT assay showed that chitosan-mediated delivery was less cytotoxic to ds-320 compared with liposome delivery. Further a modified invasion assay revealed an inhibitory effect of 320-chitosan on bacterial invasion into normal rat kidney epithelial NRK-52E cells. The establishment of infection stone model was performed by intravesical injection of 1×108 CFU of Proteus mirabilis. In animal experiments, no visible stones were obtained. The number of live bacteria and white blood cells in urine showed no difference among all infected rats at the time of sacrifice. However, we observed a decline in urine calcium and pH, suggesting the effect of acidification. Overall, our study provides evidence for the protective effect of 320-chitosan, for its ability to down-regulate urinary calcium, acidify urine, and inhibit bacteria from invading renal epithelial cells. Thus, it can be served as an important complementary therapy for infection stones.

Bacterial Characteristics of Dust Particle Saltation in Gobi Dust Sites, Mongolia

The Gobi Desert is a major source of Asian dust events, and the resulting health hazards have increased significantly in recent years. We reported that a variety of live bacteria were distributed in the Gobi Desert in relation to land use. Bacterial distribution was confirmed in the environment and on the land used by animals; however, bacterial saltation due to dust events has not been investigated in detail. In this study, to understand the distribution of surface bacteria in the atmosphere by dust saltation, live bacteria in four dust-generating areas in the Gobi area were monitored using an artificial dust generating device. The live bacteria were detected by experimental saltation at a wind speed of 6.5–8 m/s in all areas. A certain number of live bacteria are constantly saltated by dust events, and these bacteria depend on land use. Moreover, the bacterial saltation strain depended on land use and diversity, indicating that live bacteria are lifted into the environment by dust events. These findings indicate that dust events saltate environmental bacteria on the ground, suggest the risk of animal-derived bacterial saltation affected by land use, and present cross-border public health challenges to be considered in the future.

Preparation, characterization, and antibiofilm activity of cinnamic acid conjugated hydroxypropyl chitosan derivatives

In this study, cinnamic acid (CA) conjugated hydroxypropyl chitosan (HPCS) derivatives (HPCS-CA) with different degrees of substitution (DS) were successfully synthesized. The reaction was divided into two steps: the first step was to modify chitosan (CS) to HPCS, and the second step was to graft CA onto HPCS. Structural characterization and properties were carried out employing elemental analysis, Fourier transform infrared (FT–IR) spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, nuclear magnetic resonance (NMR) spectra, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The solubility test revealed the better water solubility of derivatives than CS. In addition, in vitro antibacterial and antibiofilm tests were performed. As expected, HPCS-CA derivatives exhibited good antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The MIC and MBC of HPCS-CA derivatives could reach 256 μg/mL and 512 μg/mL, respectively. Confocal laser scanning microscopy (CLSM) analysis proved the inhibitory effect of HPCS-CA derivatives on S. aureus and E. coli biofilms by disrupting the formation of biofilms, reducing the thickness of biofilms, and the number of live bacteria. These results suggest the potential applicability of HPCS-CA derivatives in the treatment of biofilm-associated infections and provide a practical strategy for the design of novel CS-based antibacterial materials.

Phage Endolysin LysP108 Showed Promising Antibacterial Potential Against Methicillin-resistant Staphylococcus aureus

As a potential antibacterial agent, endolysin can directly lyse Gram-positive bacteria from the outside and does not lead to drug resistance. Considering that XN108 is the first reported methicillin-resistant Staphylococcus aureus (MRSA) strain in mainland China with a vancomycin MIC that exceeds 8 µg mL-1, we conducted a systematic study on its phage-encoded endolysin LysP108. Standard plate counting method revealed that LysP108 could lyse S. aureus and Pseudomonas aeruginosa with damaged outer membrane, resulting in a significant reduction in the number of live bacteria. Scanning electron microscopy results showed that S. aureus cells could be lysed directly from the outside by LysP108. Live/dead bacteria staining results indicated that LysP108 possessed strong bactericidal ability, with an anti-bacterial rate of approximately 90%. Crystal violet staining results implied that LysP108 could also inhibit and destroy bacterial biofilms. In vivo animal experiments suggested that the area of subcutaneous abscess of mice infected with MRSA was significantly reduced after the combined injection of LysP108 and vancomycin in comparison with monotherapy. The synergistic antibacterial effects of LysP108 and vancomycin were confirmed. Therefore, the present data strongly support the idea that endolysin LysP108 exhibits promising antibacterial potential to be used as a candidate for the treatment of infections caused by MRSA.

Citrobacter koseri stimulates dendritic cells to induce IL-33 expression via abundant ATP production.

Introduction. Food allergies (FAs) occur due to intestinal immune dysfunction elicited by dysbiotic conditions. It was previously determined by us that Citrobacter species propagate in the faeces of mice with FAs and worsen allergic symptoms by inducing the allergenic cytokine IL-33. Dendritic cells can play important roles in regulation of FA responses.Hypothesis. Citrobacter species propagating in intestines of mice worsen allergic symptoms by stimulating dendritic cells to induce IL-33 expression.Aim. The aim of the present study was to analyse whether C. koseri stimulates dendritic cells to induce IL-33 expression.Methodology. IL-33 expression was evaluated in a DC2.4 mouse dendritic cell line stimulated by live or heat-inactivated C. koseri JCM1658, ATP, LPS extracted from C. koseri JCM1658 or other enterobacteria by real-time PCR. The ATP concentration and number of live bacteria in the culture supernatant were measured simultaneously.Results. Live C. koseri JCM1658 induced higher levels of IL-33 expression than other enterobacteria tested, but such a response was not elicited by heat-inactivated C. koseri JCM1658. LPS extracted from C. koseri JCM1658 did not induce IL-33 expression and suppressed live C. koseri JCM1658-induced IL-33 expression via the activation of Toll-like receptor 4 signalling. Furthermore, ATP produced by C. koseri JCM1658 stimulated dendritic cells to induce IL-33 expression by stimulating the P2X7 receptor, and LPS attenuated extracellular ATP-induced IL-33 expression. C. koseri JCM1658 was observed to proliferate more vigorously and produce more ATP than other enterobacteria.Conclusion. C. koseri acts as an allergenic bacterium through ATP production, stimulating dendritic cells to induce IL-33 expression, while LPS released from inactivated C. koseri JCM1658 attenuates this allergenicity.

Investigation of the effects of various stress factors on biofilms and planktonic bacteria in cooling tower model system.

Biofilm is a microbial population which live in a self-produced extracellular polymeric matrix by attaching to surfaces. Biofilms consist of different different types of organisms such as bacteria, fungi, protozoa, etc. Many biofilms that develop in nature consist of more than one type of organism. Biofilms protect bacteria from adverse conditions such as temperature fluctuation and disinfectants. The aim of this study was to determine the effective elimination strategies for combating biofilm and planktonic bacteria in cooling tower model system using different decontamination / disinfection techniques. In this study, 14week-old biofilms were treated with temperatures of 4°C, 65°C; pH of 3, 11; 2 and 10mg/l chlorine, 2 and 10mg/l monochloramine; hypotonic salt (0.01% NaCl) and hypertonic salt (3% NaCl) solution. For enumeration, number of aerobic heterotrophic bacteria was determined by conventional culture method, number of live bacteria was determined by LIVE/DEAD viability kit, CTC-DAPI and Alamar blue staining methods. Temperature of 65°C, pH of 3, 10mg/l monochloramine and hypertonic salt solution were the most effective parameters for decontamination of biofilm and planktonic bacteria. Biofilm bacteria in the circulating water system were significantly more resistant than planktonic bacteria against stress factors. When the numbers of epifluorescence microscopy and conventional culture technique were compared, significantly higher number of live bacteria were detected using epifluorescence microscopy. Bacteria enter the viable but non-culturable phase by loosing their culturability under stress conditions. For this reason, the conventional culture method should be supported by different techniques to get more realistic numbers.

AgNPs@ZIF‐8 Hybrid Material‐Modified Polyethersulfone Microfiltration Membranes for Antibiofouling Property and Permeability Improvement

AbstractMembrane fouling is a major hindrance to the effective application of polyethersulfone (PES) membranes. Synthetic silver nanoparticles @ zeolitic imidazolate framework‐8 (AgNPs@ZIF‐8) hybrid crystals were used to modify the PES microfiltration membranes for mitigating membrane fouling and better water permeability. The surface modification of AgNPs@ZIF‐8 hybrid crystals improved the antifouling property of the membranes. The number of live bacteria in the bacteria suspension was over 90 % less than that of control membranes. Furthermore, after surface modification, the membrane permeability was enhanced, which was due to increased surface hydrophilization of the membranes which could partly explain the improved antifouling property. The results demonstrate that the use of AgNPs@ZIF‐8 hybrid crystals is a feasible and attractive approach for the development of antifouling membranes.

UJI AKTIVITAS ANTIOKSIDAN DALAM BEBERAPA MINUMAN YOGHURT DENGAN METODE DPPH (1,1-Diphenyl-2-Picryhydrazil)

Antioxidants are chemical compounds that can donate one or more electrons (electron donors) to free radicals to inhibit oxidative reactions. One example that has the potential as an antioxidant is yogurt. Yogurt is a food that contains a number of live bacteria that have a beneficial effect on health because it has antioxidant, antimicrobial, antidiarrheal activity and can boost the immune system. There are several factors that can affect the antioxidant activity of yogurt including temperature, storage conditions, and additional ingredients used such as adding fruit flavors. The purpose of this study was to determine the antioxidant activity of probiotics from yogurt drinks with various brands. Samples were taken from supermarkets in Medan City with 3 different brands coded A, B, and C. The antioxidant activity was determined by the DPPH (1,1-diphenyl-2-picrylhydrazyl) method using a visible spectrophotometer measured at wavelengths. 516 nm. The results showed that there were two samples of yogurt drink coded A and B which were included in the strong category and code C samples were included in the weak category. Yogurt drink with brand code A has the strongest antioxidant activity compared to other brand yogurt drinks (B and C) with IC50 values from samples code A (80.52 ml), B (90.14 ml), and C (194, 81 ml).

The effect of human serum and dentin powder alone or in combination on the antibacterial activity of sodium hypochlorite against Enterococcus faecalis

ObjectiveDentin debris and organic components may affect the properties of intracanal irrigants. This study aimed to evaluate the effect of dentin powder (DP) and human serum (HS) on the antibacterial and antibiofilm activity of sodium hypochlorite (NaOCl) against Enterococcus faecalis. DesignDP from 100 to 6.25 mg/mL and HS from 10% to 0.3125% were interactively mixed and added into E. faecalis and 1% NaOCl solution. The live E. faecalis were counted after 1 min of contact. For biofilm testing, 7 days of E. faecalis biofilms were treated by 100 mg/mL DP and 10% HS alone or combination with 1% NaOCl solution for 1 min. Furthermore, after challenges, E. faecalis biofilms were stained with SYTO 9 and propidium iodide, and confocal laser scanning microscopy (CLSM) was used to determine the proportion of dead and live cells in the biofilm. ResultsOne hundred mg/mL DP or 10% HS alone showed the excellent inhibition of 1% NaOCl against planktonic E. faecalis, and the low concentration of DP and HS presented an additive inhibitory effect. The number of live bacteria in biofilms were significantly higher in the 1% NaOCl-treated group with DP or HS than without DP and HS (p < 0.05), and a higher percentage of dead bacteria was found in the challenge of NaOCl in the absence of DP and HS than in the presence of DP and HS. ConclusionDP and HS generated the inhibition of antibacterial and antibiofilm activities of NaOCl, whereas the effect of HS was greater than DP.