Test Bacteria Research Articles

Low-cost, real-time detection of bacterial growth via diffraction-based sensing.

The emergence of antibacterial resistance impacts healthcare networks globally, with mortality rates and linked burdens of infection disproportionately affecting the developing world. Rapid alternatives to antibiotic susceptibility testing (AST) allow for swifter, more effective treatment, though they are limited in use in low-resource settings due to significant cost barriers. Herein we demonstrate a simple, cost-effective diffraction sensing-based approach for rapidly detecting bacterial growth (a precursor to AST). Diffraction gratings (1D, lined) directly comprised of our test bacteria (Escherichia coli DH5α) were produced using soft agar-based gel templates designed to direct bacterial attachment and produce a near-zero background signal. The diffraction spot intensities from the live bacterial gratings were monitored in growth and no growth (ampicillin) conditions at room temperature, using a simple fixed laser and photodetector setup. Growth-induced differences in signal were observed within 10-20 minutes, highlighting the sensitivity of this approach and its potential to be adapted as a rapid and accessible AST alternative.

Cuminaldehyde in Combination with Ciprofloxacin Shows Antibiofilm Activity against Clinical Strains of Pseudomonas aeruginosa: A Study to Explore the Underlying Mechanism

Pseudomonas aeruginosa poses a serious threat in healthcare settings. This bacterium can develop resistance to many antibiotics, rendering even last-resort treatments ineffective. Additionally, it forms protective biofilms that shield it from the immune system, making infection treatment challenging. This study investigated the susceptibility of five clinically isolated strains of the test bacteria to a combination of ciprofloxacin and cuminaldehyde. Cuminaldehyde (a natural phytochemical) and ciprofloxacin (an antibiotic) were separately found to show antimicrobial effect against test organism. However, the combination of selected compounds showed an additive effect in their microbial growth inhibitory activity. The mentioned compounds at their sub-MIC doses subjected to test whether they could show any extent of biofilm inhibition or disintegration property against the clinical strains of P. aeruginosa. The chosen concentrations of the compounds demonstrated significant antibiofilm activity against all the tested clinical strains. Additionally, it was observed that the compounds not only accumulated reactive oxygen species (ROS) but also enhanced the cell membrane permeability of the clinical strains. These findings suggest that the combination of ciprofloxacin and cuminaldehyde could explore new directions in fighting P. aeruginosa-linked infections.

Antibacterial Activity of N-Hexan and Ethyl Acetate Fractions of Gaharu Leaves (Aquilaria malaccensis) Against Bacteria Causing Skin Infection

Gaharu (Aquilaria malaccensis) leaves are plants that are useful in the treatment of infectious diseases. This study aims to obtain n-hexane and ethyl acetate fractions of Gaharu leaves that have antibacterial activity against skin infection bacteria by agar diffusion. The results of antibacterial activity screening of the n-hexane fraction and ethyl acetate fraction at a concentration of 0.1% is bacteriostatic. The test results of Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) using concentrations of 0.1%, 0.2%, 0.4%, 0.8%, 1.6%, 3.2%, 6.4% and 12.8% obtained MIC value of n-hexane fraction at 0.2% against P. acnes, P. aeurogynes bacteria and 0.4% against S. aureus, S. epidermidis bacteria, MIC value of ethyl acetate fraction was 0.2% against P. aeuroginosa, S. aureus bacteria and 0.4% against P. acnes, S. epidermidis bacteria. MBC value of n-hexan fraction was 0.4% against P. acnes, P. aeuroginosa bacteria, 0.8% against S. aureus bacteria, 1.6% against S. epidermidis bacteria, MBC value of ethyl acetate fraction was 0.4% against P. acnes, P. aeuroginosa, S. aureus bacteria, 0.8% against S. epidermidis bacteria. The results of the antibacterial activity using concentrations of 1.56%, 3.12%, 6.25%, 12.5% and 25% obtained the largest inhibition zone diameter of the n-hexane fraction was 13,99 mm and the ethyl acetate fraction was 27,68 mm against S. epidermidis bacteria at a concentration of 25%. Based on the results, it can be concluded that the antibacterial activity of the ethyl acetate fraction against all test bacteria is stronger than the n-hexane fraction

Exploring The Antibacterial Potential of Aqueous and Ethanol Extracts from Bawang Dayak (Eleutherine palmifolia (L.) Merr) Against Skin Infectious Bacteria Through KLT-Bioautography

Dayak onion plants (Eleutherine palmifolia (L.) Merr) have chemical compounds that have potential as antibacterials such as alkaloids, glycosides, flavonoids, phenolics, steroids and tannins. This study aims to determine the antibacterial activity of water extracts and ethanol extracts of dayak onion bulbs (Eleutherine palmifolia (L.) Merr). This research was conducted with the stages of sample extraction, screening of test bacteria, bioautogram profile testing and antibacterial activity by KLT-Bioautography method. Screening test results at a concentration of 1% against test bacteria Propionibacterium acnes, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis were able to inhibit the growth of test bacteria. Then continued with KLT-Bioautography testing using n-hexan: ethyl acetate (2: 1) eluent. The KLT-Bioautography test results showed that there was 1 active spot with an Rf value of 0.63 in the water extract and an Rf value of 0.60 in the ethanol extract against Pseudomonas aeruginosa, Propionibacterium acnes, Staphylococcus aureus, and Staphylococcus epidermidis bacteria. Based on the research, water extract and ethanol extract of dayak onion bulb (Eleutherine palmifolia (L.) Merr) have potential as antibacterial.Keywords: Antibacterial, KLT-Bioautography, Dayak Onion Bulbs

Antibacterial peptides from black soldier fly (Hermetia illucens) larvae: mode of action and characterization

Antibacterial peptides from black soldier fly larvae extract were prepared using Flash column chromatography. Three out of five fractions (F2, F3 and F4) showed antibacterial activity against Listeria monocytogenes DMST 17303 with a minimum inhibitory concentration (MIC) of 1 mM, followed by Salmonella enterica Enteritidis DMST 15679 and Escherichia coli O157:H7 DMST 12743 with a MIC ranging from 4 to 8 mM. Due to the higher yield, F2 and F3 were further analyzed on their mode of action against L. monocytogenes DMST 17303. Both fractions, particularly F2, exerted antibacterial activity through inducing bacterial cell membrane disintegration and interaction with intracellular compounds including fatty acids, proteins, and nucleic acids. The F3 did not show significant hemolytic activity up to 4 mM, while F2 showed lower than 5% hemolysis up to 8 mM. Time-to-kill analysis revealed that F2 was more effective and exerted a sustainable killing effect after 2 and 4 h, depending on the concentration of 1 and 2×MIC, respectively, while the F3 at 2×MIC could completely kill the test bacteria within 24 h. Among the identified peptides in the fractions, those with charged, either positively or negatively, and moderate hydrophobicity of ranging 6.68–15.70, namely CGPPRQGPFPR, HLEEELK, LEEAEERAD, TEELEEAKKK, and KGNSELEEAKKK, are potential antimicrobial peptides.

Phytochemical analysis, antibacterial and anti-diabetic activity of three different seaweed extracts

Aim: Marine seaweed contains potential phytochemical compounds that could able to cure different health issues in humans naturally. Hence the research was aimed to investigate the antibacterial and in vitro anti-diabetic activity of three different seaweed extracts. Methods: Phytochemical compounds like phenol, flavonoids, tannins and alkaloids were quantitatively identified. Antibacterial activity of the seaweed extracts were determined against five different test bacteria. In vitro anti-diabetic activity of the extracts were investigated based on its inhibition effect on the alpha-amylase and alpha-glucosidase activity. Findings: Phytochemical analysis showed more phenolic and flavonoid content in green and brown seaweed extracts and lesser content in red seaweed extract. Antibacterial activity of green and brown seaweed extracts showed good inhibitory zones against all test bacteria ranging from 22.9 ± 0.57 mm to 24.9 ± 0.57 mm (green seaweed extract) and 17.9 ± 0.57 mm to 21.6 ± 0.75 mm (brown seaweed extract) respectively. In vitro anti-diabetic activity of seaweed on the inhibition of enzymes showed promising results. Among the three types, green seaweed extracts showed maximum inhibition of α-Amylase and α-glucosidase activity of 86.6 ± 0.76 % and 82.9 ± 0.57 % respectively. Conclusion: Findings showed that the phytochemicals present in the methanolic extract of seaweeds attribute positively for different pharmacological properties like antibacterial, anti-oxidant and anti-diabetic activity. Optimizing the production factors would able to commercialize the seaweeds in drug forms and could be used for the treatment of various diseases in humans.

Effectiveness of Butterfly Pea ( Clitoria Ternatea ) Extract Against Streptococcus Mutans Bacterial Growth In Vitro

Dental caries is still a major problem in dentistry and is the most common infectious disease in children. Caries is a microbiological infectious disease that can damage the hard tissue of the teeth. This study aims to determine the effectiveness of butterfly pea flower extract ( Clitoria ternatea ) on the growth of Streptococcus mutans in vitro. This type of research is laboratory experimental research using a post test only control group design approach The samples used were butterfly pea flower extract ( Clitoria ternatea ) diluted with DMSO to a concentration of 100%, 50%, 25%, 12.5%, 3.125%, 6.125% and Streptococcus mutans ATCC 25175. This research was conducted using the MIC test dilution method and KBM to see the effectiveness of the antibacterial extract against the test bacteria. Analysis of research data using the one way ANOVA test (p <0.05) to see significant differences between study groups with the number of test bacteria, followed by a double comparison test with the Post Hoc Least Significance Different (LSD) method to determine the average difference between treatment groups. Antibacterial effectiveness test results showed that butterfly pea flower extract ( Clitoria ternatea ) was effective in inhibiting Streptococcus mutans bacteria (p<0.05), at a concentration of 25% was the minimum inhibitory level (MIC) and 50% concentration was the minimum killing rate (MBC). ). The conclusion of this study is that the extract of butterfly pea flower ( Clitoria ternatea ) is effective in inhibiting and killing Streptococcus mutans bacteria.

A-243 Quantitative Bacteriology Parameters for Seal-Packaged Agar Plates Challenged with Experimental Low-resource Tropical Field Clinic Stress

Abstract Background InTray® Mueller Hinton Chocolate (MHC) and Colorex™ Screen (CS) plates are in vitro diagnostic devices combining prepared bacteriological agar-media with Biomed’s ‘InTray®’ format (a double sealed-packaging cassette system that provides extended shelf-life 12 months past the date of manufacture). The devices are intended for use with clinical specimens to culture, isolate and identify potentially pathogenic bacteria. This study evaluated MHC and CS device performance at 7 and 13 months past the date of manufacture after product was experimentally challenged with stress replicating a low-resource tropical field clinic scenario. Methods MHC and CS plates were exposed to high temperature (40.5°C ± 0.5) and high humidity (74.5 ± 2.5% relative humidity) for an extended time-period (18 days). After the 18 days of heat treatment, the stress-group plates were stored in the lab at working room temperature (20-25°C) for the remainder of the study. Quantitative differences between control-groups (stored under refrigeration: 2-8°C) and heat-stress treatment groups for both MHC and CS were examined via CFU/mL measurements comparing three different lab-strain bacteria chosen based on clinical sub-culturing prevalence from blood bottles; Escherichia coli (ATCC 25922), Streptococcus pneumoniae (ATCC 6305), and Staphylococcus aureus (ATCC 25923). Briefly, 24-hour (18-30 h) old bacterial colony suspensions (grown on MHC) were prepared in 0.85% saline solution, adjusted to a 0.5 McFarland standard (here defined as 0.08-0.96 Absorbance @ 625 nm), measured in triplicate and diluted. A 20 μL volume from the lowest dilution (2.5 x 103 CFU/mL) was then spread-plated to each plate in order to count colony-forming units (CFU) in the acceptable range of 25-250. Results Quantitative CFU/mL differences between control-groups (stored under refrigeration: 2-8°C) and heat-stress-treatment groups (>40°C and high humidity) for MHC and CS for three different test bacteria (listed above) were not statistically significant when tested at 13 months. The CS stress and control group comparison for S. pneumoniae with a p value < 0.05 at 7 months had a p value > 0.05 at 13 months, suggesting that the difference between the CFU counts may not be significant in biological terms. Conclusions In conclusion, control and heat-stress treatment groups for both MHC and CS met acceptable performance criteria as expected for the products, 13 months after the date of manufacture.

A-277 Viability of multi-drug resistant organisms in a fecal collection and transport system stored at ultra-low temperature

Abstract Background Epidemiological studies are constantly investigating new, easier ways to collect and store patient specimens that allow for flexible testing windows and long-term storage as well as accurate quantification of organisms of interest. The FecalSwabTM system (Copan, Brescia, Italy) is intended for the collection and preservation of rectal and fecal specimens. This system includes a preservation medium which serves to maintain the viability of enteric pathogens during transport to a clinical laboratory for up to 72 hours at 4oC. The objective of this study was to assess the continued viability of multi-drug resistant organisms (MDROs) suspended in the FecalSwab sample format when frozen at -80°C and the impact of freeze-thaw cycles. Methods A total of 40 organisms were chosen spanning methicillin-resistant Staphylococcus aureus (MRSA, n=10), carbapenem-resistant Pseudomonas aeruginosa (CRPA, n=5), carbapenem-resistant Enterobacterales (CRE, n=5), vancomycin-resistant Enterobacterales (VRE, n=10) and extended-spectrum beta-lactamase containing Enterobacterales (ESBL, n=10). Each organism was spiked into FecalSwab at standardized concentrations. At each time point, FecalSwab media was plated onto blood agar and colonies were quantified. Each of the 40 organisms were assessed one-week post-freeze and over the course of freeze-thaw cycles at days 3 and 5. The survival of each MDRO was evaluated by calculating a difference between the concentration of organisms recovered (CFU per 10uL media) at each time point and the concentration of organisms confirmed present at the time of inoculation. Percent recovery was calculated from this difference. Results One week after freezing, the percent recovery for MRSA, VRE, ESBL, CRE, and CRPA averaged to 102%, 201%, 17.8%, 7.6%, and 0.8%, respectively (Kruskal Wallis p < 0.001), with significant differences noted between gram positive and gram negative organisms (Kruskal Wallis p <0.001). Conclusions Epidemiological studies interested in MDRO surveillance rely on methodologies that allow for accurate quantification of viable organisms. In this study, we’ve evaluated the viability of several multi-drug resistant organisms when frozen at -80°C in the FecalSwab. The FecalSwab system is intended for the collection of rectal swab and fecal specimens and to preserve the viability of enteric pathogenic bacteria for testing in the clinical laboratory. Although it was not specifically designed to preserve MDROs, it performed well with MRSA and VRE, but less well with CRE, CRPA and ESBL organisms. When using the FecalSwab system, the observed gram-specific differences may inform the suitability of this system depending on the organism(s) of interest.

Screening of Extract Secondary Metabolites of Bacteria Which Have Symbiosis with Sponges from Central Tapanuli Bakar Island as an Antibacteria

This study aims to determine the presence of antibacterial-producing bacteria from sponges from Bakar Island, Central Tapanuli Regency and to determine the antibacterial activity of methanol extracts from potential bacterial isolates against Staphylococcus aureus and Escherichiacoli. 21 pure isolates were found and it was known that 9 isolates produced antibacterial against S. aureus and 4 isolates against E. coli. Bacterial isolates with the highest inhibition zone against bothS.aureus and E. coli were found in isolates with code SP20 with each large inhibition zone are 14.5 mm and 16.04 mm. Then microscopic observations were carried out, namely gram staining and were obtained 8 isolates were gram positive, and 1 gram was negative. The biochemical test showed that SP20 showed positive results for the Motility, TSIA and Catalase Test but negative for Citrate Test. Bacterial isolates withthe code SP20 had the largest inhibition zone so that these isolates were to be extracted.The resultsof the screening test showed that the secondary metabolitesof the sponge symbiont bacterial extract from Bakar Island were positive for flavonoids and saponins. And then test the activity of secondary metabolites with 3 concentrations, 10%, 20%, and 30%.The results showed that the best concentration of the test bacteria was S. aureus at a concentration of 30% with an inhibition zone of 3.08 mm and E. coli at 5.04 mm.

Nutmeg vs mace: Evaluation of functional, nutritional, antioxidant and antimicrobial traits to employ as a food preservative

Nutmeg and mace from Myristica fragrans Houtt. are renowned for their culinary significance and medicinal properties. This study was designed to analyze the functional properties, proximate and mineral composition of nutmeg and mace, phytochemical estimation, antioxidant and antimicrobial potential of nutmeg and mace essential oils and oleoresins. The study was further elaborated by testing their synergistic interaction with streptomycin and antibiofilm potential of the most effective treatment. Results revealed better functional properties, higher fiber (35.2%) and mineral (K, Mg, P, Ca, Mn, Zn) content in nutmeg than mace. Nutmeg and mace essential oils were isolated by hydrodistillation and their respective oleoresins were prepared by the Soxhlet extraction method. Phytochemical screening showed a greater phenolic content in mace oleoresin (43.85 mg GAE/g of dw) and terpenoid content in mace essential oil (75.4%). Among all the treatments, mace oleoresin revealed best antioxidant potential against mustard oil degradation during its accelerated oxidation at 70 °C when stored for 7–28 days with minimum increase in peroxide, anisidine, thiobarbituric acid and total oxidation values of mustard oil. Mace oleoresin also revealed the maximum antibacterial activity against Staphylococcus aureus, Bacillus spp., Escherichia coli and Yersinia enterocolitica (MIC values; 180–530 μg/ml). It also revealed synergistic interaction with streptomycin against all the test bacteria along with a notable decrease in biofilm formation (50% of MIC.) GC-MS studies of mace oleoresin showed the presence of terpenoids, phenylpropanoids, phenols and fatty acids and their esters. Hence, mace oleoresins may be used as a natural and safe food preservative.

Isolation and identification of enteric bacteria from different water sources at Mymensingh city, Bangladesh and their antibiogram study

The goal of the current study was to separate and characterize the enteric bacteria found in water samples taken from various Mymensingh municipal sources and places. A total of 40 water samples were examined. Through the use of polymerase chain reaction (PCR), biochemical testing, staining, and culturing enteric bacteria were isolated and identified. The antibiotic resistance phenotype was examined using the disk diffusion assay. Out of 40 isolates that tested positive for bacterial growth, 3 (7.5%) were identified as Salmonella spp., 6 (15%) as Shigella spp., 14 (35%) as E. coli, and 3 (7.5%) as Vibrio spp. Molecular detection of Salmonella spp. were confirmed by PCR-based detection of the bcfC gene, Shigella species by the invC gene, E. coli by the 16S rRNA gene, and Vibrio spp. by the groEL gene. Furthermore, PCR-confirmed isolates were tested for antibiotic resistance to 12 routinely used antibiotics. All Salmonella isolates were 100% resistant to Amoxicillin but 100% sensitive to Azithromycin. However, varied sensitivity was seen against Cefepime (80%), Gentamycin (80%), Levofloxacin (75%), Cotrimoxazole (74%), and Amikacin (70%). The isolates also showed resistance to Ceftazidime (70%), as well as Ceftriaxone (33%). Shigella spp. isolates showed increased resistance to Cefepime (83%) and Ceftazidime (67%). Additionally, resistance to Amoxicillin (17%) and Colistin (10%) was shown to be lower. In addition, Azithromycin, Levofloxacin, Cotrimoxazole, Ceftriaxone, Amikacin, and Gentamicin showed nearly no resistance or significant susceptibility E. coli isolates showed stronger resistance patterns to amoxicillin (100%), and colistin (93%). Cefepime (72%), Cotrimoxazole (72%), and Azithromycin (72%). The lower levels of resistance to ceftriaxone, amikacin, ceftazidime, levofloxacin, and gentamicin were also seen. The higher resistance patterns were shown by the isolated Vibrio spp. against Ampicillin (100%), Cefepime (81%), Cefixime (72%), Amoxicillin (70%), Erythromycin (67%), and Ceftazidime (67%). On the other hand, isolates with high and moderate sensitivity were found to be gentamicin, levofloxacin, doxycycline, cotrimoxazole, and amikacin. The study’s conclusions point to recent and ongoing contamination of the water sources, putting residents who depend on the water for drinking at risk for gastrointestinal illnesses.

Host heterogeneity in humoral bactericidal activity can be complement independent.

Humoral bactericidal activity was first recognized nearly a century ago. However, the extent of inter-individual heterogeneity and the mechanisms underlying such heterogeneity beyond antibody or complement systems have not been well studied. The plasma bactericidal activity of five healthy volunteers were tested against 30 strains of Gram-negative uropathogens, Klebsiella pneumoniae and Escherichia coli, associated with bloodstream infections. IgG and IgM titers specific to K. pneumoniae strains KP13883 and KPB1 were measured by ELISA, and complement inhibitor was used to measure the contribution of complement-induced killing. Furthermore, MALDI-TOF mass spectrometry was conducted to determine the metabolomic components of plasma with bactericidal properties in 25 healthy individuals using Bayesian inference of Pearson correlation between peak intensity and colony counts of surviving bacteria. Plasma bactericidal activity varied widely between individuals against various bacterial strains. While individual plasma with higher IgM titers specific to K. pneumoniae strain KP13883 showed more efficient killing of the strain, both IgM and IgG titers for K. pneumoniae strain KPB1 did not correlate well with the killing activity. Complement inhibition assays elucidated that the complement-mediated killing was not responsible for the inter-individual heterogeneity in either isolate. Subsequently, using MALDI-TOF mass spectrometry on plasmas of 25 healthy individuals, we identified several small molecules including gangliosides, pediocins, or saponins as candidates that showed negative correlation between peak intensities and colony forming units of the test bacteria. This is the first study to demonstrate the inter-individual heterogeneity of constitutive innate humoral bactericidal function quantitatively and that the heterogeneity can be independent of antibody or the complement system.

Evaluation of the Stability and Antibacterial Activity of Burow's and Neo-Burow's Solutions was Prepared Using Different Methods

Burow's solution is a 13% aluminum acetate solution used for treating chronic suppurative otitis media. However, multiple formulations for Burow's and neo-Burow's solutions are used as in-hospital preparations. Each formulation uses different types and amounts of reagents, and takes a different time to prepare. Thus, the ions, including aluminum ion (Al3+), and other molecules in the prepared Burow's and neo-Burow's solutions are not identical, and the pH also differs. Furthermore, details about the antibacterial activity of these preparations are unknown. This study evaluated the stability and antibacterial activity of four Burow's and two neo-Burow's solutions prepared using different methods. Preparation times ranged from 20 min to 3 d, and the pH ranged from 2.2 to 4, meaning some solutions were more acidic or more basic than the pH 3 devised by Burow. In addition, the Al3+ concentrations ranged from 0.05 to 1.51 mol/L, meaning some solutions were more concentrated or diluted than 13% aluminum acetate (0.64 mol/L). One of the Burow's solutions we prepared produced a white residue after 14 d, making it difficult to ensure stability. In addition, confirming the antibacterial activity of another Burow's solution against the test bacteria was problematic. Despite the differences in pH and Al3+ concentrations between the various Burow's and neo-Burow's solutions, the antibacterial activity was equivalent. It was considered necessary to use the basic data obtained in this study to select a formulation for each hospital. Evaluation of the antibacterial activity of each formulation in clinical settings will be a subject for future study.

Curcumin loaded starch-based aerogels interfere with quorum sensing regulated virulence functions and biofilm of bacterial pathogens

Over the last two decades, the sharp escalation of antimicrobial resistance (AMR) has emerged as a formidable threat to human health. This pressing situation demands innovative interventions to combat infectious diseases. Aerogels, characterized by their nanostructured composition and high porosity, present a promising avenue. In this study, we manufactured curcumin loaded starch-based aerogels (CSA) and evaluated their impact on the quorum sensing (QS) mechanism in Gram-negative bacteria. Fourier-transform infrared (FTIR) analysis highlighted the presence of cellulose hydroxyl groups engaged in hydrogen bond formation. Thermogravimetric analysis (TGA) revealed that over 50 % of the initial mass was lost when CSA underwent heating to 350 °C. Microscopic examination showcased a uniform and compact pattern, suggesting reduced pore distribution. The elemental composition analysis indicated that carbon and oxygen constituted 23.00 % and 77.00 % of the weight, respectively. The presence of CSA resulted in over 30.4 % inhibition of violacein pigment production. Furthermore, CSA modulated pyocyanin production, pyoverdin production, LasB elastase activity, and rhamnolipid production by 34.4 %, 31.07 %, 22.7 %, and 19.7 %, respectively. The total exoproteases, cell surface hydrophobicity and exopolysaccharide production in E. coli, L. monocytogenes, S. marcescens, and P. aeruginosa, experienced a significant decrease at sub-MICs. Production of biofilms as well as the mature biofilms in test bacteria were reduced in dose-dependent manner significantly. Due to their antibiofilm and anti-quorum sensing properties, these CSAs could prove to be functional biomaterials with versatile applications, particularly in the food industry.

As next-generation probiotics: acetic acid bacteria isolated from Kombucha beverages produced with Anatolian hawthorn leaves.

This research examined acetic acid bacteria (AAB) isolated from Kombucha beverages produced with Anatolian hawthorn (Crataegus orientalis) as next-generation probiotics. Eighty-six AAB were isolated from the samples and investigated in terms of biosafety, viability in vitro gastrointestinal conditions, technological and bioactive properties, and also in vitro adhesion abilities. Seventy-six isolates demonstrating γ-hemolysis exhibited resistance to erythromycin and ampicillin. Besides, these isolates survived at low pH and in the presence of bile salts. However, the majority of AAB isolates showed tolerance to phenol, pepsin, and pancreatin. Also, twenty-one isolates showed protease enzyme activity, while eight isolates had amylase enzyme activity. Despite most of the isolates showed viability at 1.5% salt, only 19 isolates survived at 10% salt. Most AAB isolates exhibited inhibition zones ranging from 8 to 26mm against test bacteria, their antioxidant activities were above 80%. Additionally, some isolates exhibited auto-aggregation ability ranging from 0.66 to 23.62% and co-aggregation ability ranging from 1.18 to 71.32%, while hydrophobicity ranged from 1.32 to 69.87% toward xylene. Finally, the indigenous 76 AAB isolates that had remarkable probiotic properties were characterized based on 16S rRNA gene sequencing, and the isolates belonged to Komagateibacter sp. (64.47%), Komagateibacter saccharivorans (15.79%), K. rhaeticus (11.84%), and Gluconobacter sp. (7.90%). As a result, the isolates identified as Gluconobacter sp. A21, Komagataeibacter sp. A139, Gluconobacter sp. A141, and Komagataeibacter sp. A146, which showed high viability under gastrointestinal conditions, safe and acceptable in terms of technological, bioactive, and adhesion properties and could be evaluated as next-generation probiotics.

Three-dimensional porous polycaprolactone/chitosan/bioactive glass scaffold for bone tissue engineering

Three-dimensional (3D) porous scaffolds based on polycaprolactone (PCL)/chitosan (CS)/bioactive glass (BG) nanoparticle composites were fabricated by the freeze-drying technique for bone tissue engineering. The physiochemical properties of the developed PCL/CS/BG scaffolds were studied using FTIR, XRD, EDX and SEM. Furthermore, the swelling degree, porosity, water retention ability, compression strength, in vitro biodegradation, bioactivity and biocompatibility of the scaffolds were examined. The PCL/CS/BG scaffolds with 4 wt. % of BG content presented adequate pore size (106 μm), porosity (156%), water swelling degree (128%), water retention ability (179%), compressive strength (3.7 MPa) and controlled degradation behavior, which could be ideal for bone tissue engineering. The PCL/CS/BG composite scaffolds showed good antimicrobial activity against both test bacteria and fungi. The MTT assay demonstrated the biocompatibility of PCL/CS/BG scaffolds against C3H10T1/2 cell line. The Alizarin red staining assay confirmed the osteogenic activity of the PCL/CS/BG scaffolds.

Article Review: Potential use of Andaliman Fruit as an Antibacterial

This research examines the potential of andaliman fruit (Zanthoxylum acanthopodium) as an antibacterial agent. Andaliman fruit is known to contain bioactive compounds such as alkaloids, flavonoids and saponins which have the potential to inhibit the growth of pathogenic bacteria. The antibacterial activity test was carried out using the agar diffusion method against several test bacteria, including Escherichia coli and Staphylococcus aureus. The results showed that andaliman fruit extract had significant antibacterial activity, indicated by the inhibition zone formed around the extract impregnation disc. The highest activity was noted against Staphylococcus aureus, which is a gram-positive bacterium. These findings indicate that andaliman fruit has the potential to be developed as an effective natural antibacterial agent. Further research is needed to identify the specific active compound and its antibacterial mechanism of action.

Anti-microbial, anti-biofilm, and efflux pump inhibitory effects of ellagic acid-bonded magnetic nanoparticles against Escherichia coli isolates.

The spread of microbial resistance is a threat to public health. In this study, the anti-microbial, anti-biofilm, and efflux pump inhibitory effects of ellagic acid-loaded magnetic nanoparticles (Fe3O4NPs@EA) against beta-lactamase producing Escherichia coli isolates have been investigated. The effects of Fe3O4 NPs@EA on the growth inhibition of E. coli isolates were determined by disc diffusion method and determining the minimum inhibitory concentration was done using broth micro-dilution method. The anti-biofilm effect of nanoparticles was investigated using the microplate method. The efflux pump inhibitory effect of nanoparticles was investigated using cart-wheel method and by investigating the effect of nanoparticles on acrB and tolC genes expression levels. Fe3O4 NPs@EA showed anti-bacterial effects against test bacteria, and the MIC of these nanoparticles varied from 0.19 to 1.56 mg/mL. These nanoparticles caused a 43-62% reduction in biofilm formation of test bacteria compared to control. Furthermore, efflux pump inhibitory effect of these nanoparticles was confirmed at a concentration of 1/8 MIC, and the expression of acrB and tolC genes decreased in bacteria treated with 1/4 MIC Fe3O4 NPs@EA. According to the results, the use of nanoparticles containing ellagic acid can provide a basis for the development of new treatments against drug-resistant E. coli. This substance may improve the concentration of antibiotics in the bacterial cell and increase their effectiveness by inhibiting the efflux in E. coli isolates.

Antarctic Spore-Forming Microorganisms from Deception Island Inhibit the Growth of Various Bacterial Strains

Antarctic microbes have evolved and adapted unique strategies to survive in the harsh polar environment. Apart from the ability to adapt to the low nutrient soil content and extremely dry and cold polar environment, a particular strategy used by Antarctic bacteria is the production of antimicrobial compounds that can eliminate rivals in the same niche, giving them a competitive edge over other microbes. In contrast, it is unclear whether spore-forming microbes possess similar antimicrobial properties as one of their survival strategies, especially those from the Antarctic volcanic Deception island in the West Antarctic. Hence, this study aims to isolate and characterize the spore-forming microbes in Deception Island, Antarctica, as well as to identify the ones that are equipped with the ability to inhibit other microorganisms. Microbes were isolated using various growth media and were segregated into clusters based on their random amplified polymorphic DNA (RAPD) fingerprints. A total of 90 strains were isolated and clustered into 30 groups at a similarity of 60%. Representative strains from each cluster were assayed for antimicrobial activities against 13 Gram-positive and Gram-negative test bacteria comprising human pathogens. Twenty-five strains exhibited the ability to inhibit at least one test bacterium. The four strains, A60, Im31, Im32 and Im33 that showed the strongest inhibitory activities were subjected to 16S or 18S rDNA sequencing and analysis to identify them. They were identified as Pseudogymnoascus, Bacillus, Leohumicola, and Talaromyces spp. The ability of the aforementioned microbes to thrive in harsh environments and compete with fierce competitors for scarce nutrients is probably due to their ability to produce antimicrobial compounds that target and kill their rivals.