Food Pathogenic Bacteria Research Articles

Transfer of beef bacterial communities onto food-contact surfaces.

Food spoilage and pathogenic bacteria on food-contact surfaces, especially biofilm-forming strains, can transfer to meats during processing. The objectives of this study were to survey the bacterial communities of beef cuts that transfer onto two commonly used food-contact surfaces, stainless steel (SS) and high-density polyethylene (HDPE) and identify potentially biofilm-forming strains. Top round, flank, chuck, and ground beef were purchased from 3 retail stores. SS and HDPE coupons (approximately 2cm × 5cm) were placed on beef portions (3h, 10°C), after which, the coupons were submerged halfway in PBS (24h, 10°C). Bacteria from the beef cuts and coupon surfaces (n = 3) were collected, plated on tryptic soy agar plates and incubated (5 days, 25°C). Bacterial isolates were identified by 16S rRNA gene amplicon sequencing and assayed for biofilm formation using a crystal violet binding (CV) assay (72h, 10°C). Additionally, beef and coupon samples were collected for bacterial community analysis by 16S rRNA gene amplicon sequencing. Sixty-one of 972 beef isolates, 29 of 204 HDPE isolates, and 30 of 211 SS isolates were strong biofilm-formers (Absorbance>1.000 at 590 nm in the CV assay). Strong-binding isolates identified were of the genera Pseudomonas, Acinetobacter, Psychrobacter, Carnobacterium, and Brochothrix. Coupon bacterial communities among stores and cuts were distinct (p < 0.001, PERMANOVA), but there was no distinction between the communities found on HDPE or SS coupons (p > 0.050, PERMANOVA). The bacterial communities identified on the coupons may help determine the communities capable of transferring and colonizing onto surfaces, which can subsequently cross-contaminate foods.

CRISPR-Cas12a-based nanoparticle biosensor for detection of pathogenic bacteria in food

Pathogenic bacterial contamination of food is a major challenge in food safety and public health management. To monitor pathogenic bacteria in food, a rapid, sensitive, and specific pathogen detection method is needed. CRISPR-Cas12a has been developed as a sensitive method for detecting pathogenic bacteria, but its output signal is fluorescent, which need equipment to detect. Here, the nanoparticle probe was designed to detect the activity of Cas12a and were able to visualize the assay results by observing the color change by naked eyes. The target sequences of pathogenic bacteria were amplified by recombinase polymerase, then recognized and bound by the crRNA and Cas12a complex. The activated Cas12a cleaved the linker-ssDNA connecting the nanoparticles, causing the nanoparticles to transition from aggregation to dispersion, and the color showed as purple. The sensitivity analysis showed that the limits of detection (LOD) reached 1 × 10°CFU/mL, 1 × 104 CFU/mL, 1 × 102 CFU/mL, 1 × 103 CFU/mL, 1 × 101 CFU/mL for Escherichia coli, Salmonella typhimurium, Vibrio parahaemolyticus, Staphylococcus aureus, and Listeria monocytogenes, which were all specific for five bacteria in the milk samples. Therefore, this method is a dependable, fast, sensitive and specific method, which make the CRIPSR-Cas12a detection method more useful in bacterial pathogenic detection.

Detecting Bacteria with Ultralow Concentrations by Enzymatic Cascade Reaction-Amplifying Strategy.

Bacteria can cause infectious diseases even at ultralow concentrations (<1 CFU/mL). It is important to rapidly identify bacterial contamination at ultralow concentrations. Herein, FITC-labeled gelatinase-sensitive nanoparticles (GNPs@FITCs) and NFM@GNP@FITCs are designed and fabricated as ultralow concentration bacteria detection platforms based on an enzymatic cascade reaction-amplifying strategy. Bacterial secretions could trigger the dissociation of GNPs@FITCs to release FITC, with gelatinase used as the model secretion. The detectable signal of ultralow concentration bacteria could be amplified effectively by the gelatinase-triggered cascade reaction. Bacterial concentration was evaluated by the change in fluorescence density. The results showed that the GNPs@FITCs and NFM@GNP@FITCs could be used for identifying bacterial contamination qualitatively, even when the bacterial contamination is lower than 1 CFU/mL. Moreover, the method has better timeliness and convenience, when compared with national standards. As solid films, NFM@GNP@FITCs have better long-term storage stability than GNPs@FITCs. The potential applications of GNPs@FITC and NFM@GNP@FITCs were proved by detecting pathogenic bacteria in food. All the results showed that the method has great potential for screening pathogenic bacterial contamination qualitatively.

Magnetic Fe3O4@MOF@aptamer-mediated entropy-driven fluorescence biosensor for multiplexed and DNA extraction- and amplification-free detection of pathogenic bacteria

Rapid and early identification of pathogenic bacteria in food and clinical samples is critical for infectious disease control and precision medicine. In this study, we present a novel Magnetic Fe3O4@metal–organic framework (MOF)@Aptamer-based Entropy-driven fluorescence biosensor combined with mesophilic Clostridium butyricumArgonaute (CbAgo) for multiplexed and DNA extraction- and amplification-free detection of pathogenic bacteria, termed the MAEA biosensor. In this study, magnetic zirconium-based MOF nanoparticles were modified with a phosphorylated aptamer as an efficient signal converter, which recognized the pathogens and released the complementary DNA to activate the entropy-driven circuit reaction. The highly efficient catalytic DNA circuit and isothermal enzyme-free format produce large amounts of guide DNA. CbAgo exerts precise and highly efficient endonuclease activity under the guidance of guide DNA, which makes the MAEA biosensor useful for multiplexed and DNA extraction- and amplification-free detection of pathogenic bacteria with high sensitivity (<102 CFU/mL). This study demonstrates a highly selective and reliable magnetic Fe3O4@MOF@aptamer-based biosensor using CbAgo for simultaneously detecting multiple pathogenic bacteria, providing a potential tool for other infectious disease pathogens with convenient operation and high sensitivity.

Endoprotein-activating DNAzyme assay for nucleic acid extraction- and amplification-free detection of viable pathogenic bacteria

Pathogenic bacteria in food or environment, can pose threats to public health, highlighting the requirement of tools for rapid and accurate detection of viable pathogenic bacteria. Herein, we report a sequential endoprotein RNase H2-activating DNAzyme assay (termed epDNAzyme) that enables nucleic acid extraction- and amplification-free detection of viable Salmonella enterica (S. enterica). The direct detection allows for a rapid detection of viable S. enterica within 25 min. Besides, the assay, based on sequential reporting strategy, circumvents internal modifications in the DNAzyme's active domain and improve its catalytic activity. The multiple-turnover DNAzyme cutting and the enhanced catalytic activity of DNAzyme render the epDNAzyme assay to be highly sensitive, and enables the detection of 190 CFU/mL and 0.1% viable S. enterica. The assay has been utilized to detect S. enterica contamination in food and clinical samples, indicating its potential as a promising tool for monitoring pathogen-associated biosafety.

Precise, Sensitive Detection of Viable Foodborne Pathogenic Bacteria with a 6-Order Dynamic Range via Digital Rolling Circle Amplification.

The presence of viable pathogenic bacteria in food can lead to serious foodborne diseases, thus posing a risk to human health. Here, we develop a digital rolling circle amplification (dRCA) assay that enables the precise and sensitive quantification of viable foodborne pathogenic bacteria. Directly targeting pathogenic RNAs via a ligation-based padlock probe allows for precisely discriminating viable bacteria from dead one. The one-target-one-amplicon characteristic of dRCA enables high sensitivity and a broad quantitative detection range, conferring a detection limit of 10 CFU/mL and a dynamic range of 6 orders. dRCA can detect rare viable bacteria, even at a proportion as low as 0.1%, which is 50 times more sensitive than the live/dead staining method. The high sensitivity for detecting viable bacteria accommodates dRCA for assessing sterilization efficiency. Based on the assay, we found that, for pasteurization, slightly elevating the temperature to 68 °C can reduce the heating time to 10 min, which may minimize nutrient degradation caused by high-temperature exposure. The assay can serve as a precise tool for estimating the contamination by viable pathogenic bacteria and assessing sterilization, which facilitates food safety control.

An NMR immunosensor based on streptavidin-biotin signal amplification for rapid detection of Salmonella in milk

Sensitive and accurate detection of harmful pathogenic bacteria in food is of great significance to public health. In this paper, a nuclear magnetic resonance (NMR) sensor based on biological signal amplification was constructed. The carboxymethyl dextran (CMD) was used as both the probe skeleton and the chelating agent to realize the fast chelating adsorption of the signal source gadolinium ion. Finally, the magnetic complex and biotinylated antibody formed an immune probe through the biological bridge to achieve rapid capture of Salmonella. In addition, non-target bacteria such as Proteus vulgaris and Listeria monocytogenes were used to test the specificity of the constructed sensor. The sensor can detect Salmonella within 1.5 h under optimal conditions, the detection limit in milk is 7.4 × 103 CFU mL−1, and the RSD (Relative standard deviation) of reproducibility experiment is 2.35%, which has good reproducibility.

ITO-Coated Vertical Nanowires-Based Biosensors for the Label-Free Detection of Escherichia coli

A major concern in public health is the direct in-situ detection of pathogenic bacteria in food, beverages, and the air [1]. This study utilizes ITO-coated vertical nanowires (ITO-VNWs) as sensing substrates for the detection of Escherichia coli (E. coli). The innovation in this research lies in the direct detection of various concentrations of E. coli using boronic acid (BA)-modified ITO-VNWs connected to a benchtop E4980A precision LCR meter. Impedance spectra were expressed in terms of real and imaginary parts, corresponding to resistance (R) and reactance (X). Serial dilutions of E. coli were prepared in saline for bacterial enumeration and tested using the standard plate count method. Subsequently, 100 μl of each bacterial dilutions (107, 106, 105, 104, 103, 102, and 101 CFU/ml) were applied to BA-modified ITO-VNWs. In summary, BA-modified ITO-VNWs demonstrated accurate and distinct detection of varying concentrations of E. coli. This accomplishment highlights the promising potential of our BA-modified ITO-VNW biosensor for precise bacterial detection across diverse applications. Further exploration and optimization of this platform could lead to advancements in the rapid and specific identification of pathogenic bacteria, making it an invaluable tool in the realm of public health and environmental safety. REFERENCES [1] A. Ahmed, J.V. Rushworth, N.A. Hirst, P.A. Millner, Biosensors for whole-cell bacterial detection, Clin Microbiol Rev 27(3) (2014) 631-46. Figure 1

Potential of bacteriophage phT4A as a biocontrol agent against Escherichia coli in food matrices

Escherichia coli is one of the most prevalent foodborne pathogens, frequently found in meat and dairy products. Current decontamination methods are often associated with changes in organoleptic characteristics, nutrient loss, and potentially harmful side effects. Furthermore, despite the array of available methods, foodborne outbreaks still frequently occur. For this reason, bacteriophages (or simply phages) emerged as a natural alternative for the biocontrol of bacterial contamination in food without altering their organoleptic properties. In this study, the potential of phage phT4A was assessed in the biocontrol of E. coli in liquid (milk) and solid (ham) food matrices. Firstly, as foods have different pH and temperature values, the influence of these parameters on phage phT4A viability was also assessed to develop an effective protocol. Phage phT4A proved to be stable for long storage periods at pH 7–8 (56 days) and temperatures of 4–37 °C (21 days). Before application of phages to inactivate pathogenic bacteria in food, previous assays were carried out in Tryptic Soy Broth (TSB) to study the dynamics of phage-bacteria interaction. Then, the antibacterial potential of phage phT4A was evaluated in the two food matrices at different temperatures (4, 10 and 25 °C). This phage was more efficient at 25 °C in all tested matrices (maximum inactivation of 6.6, 3.9 and 1.8 log CFU/mL in TSB, milk and ham, respectively) than at 10 °C (maximum decrease of 4.7, 2.1 and 1.0 log CFU/mL in TSB, milk and ham, respectively) and 4 °C (maximum reduction of 2.6 and 0.7 log CFU/mL in TSB and milk, respectively). However, the decrease of temperature from 25 °C to 10 and 4 °C prevented bacterial regrowth. The results suggest that during phage treatment, a balance between an incubation temperature that provide effective results in terms of bacterial inactivation by the phages and at the same time prevents or delays bacterial regrowth, is needed. The application of phage phT4A at a temperature of 10 °C can be an effective strategy in terms of bacterial inactivation, delaying bacterial regrowth and also reducing energy costs.

Antimicrobial efficacy of select medicinal plant extracts from Bangladesh against food‐borne bacterial pathogens

AbstractWe assessed the antimicrobial activity of extracts prepared with four solvents (hexane, acetone, ethanol, water) from 45 medicinal plants used in Bangladesh. Food pathogenic bacteria (Gram‐positive: Bacillus cereus, Listeria innocua, Streptococcus faecalis, and Gram‐negative: Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, and Shigella sonnei) were tested using a broth microdilution method. The extraction yield was highest (26%) for the water extract of Carica papaya and lowest (0.4%) for the acetone extract of Cynodon dactylon. In general, acetone extracts exhibited much more antibacterial activity than those obtained with the other three solvents (hexane, ethanol, and water). Gram‐positive bacteria were more sensitive than Gram‐negatives. Streptococcus faecalis was the most susceptible to inhibition by examined extracts, whereas E. coli and P. aeruginosa were the most resistant. Most inhibitory concentration‐50 (IC50) values ranged between 101 and 500 μg/mL (64 extracts, 35.5%), followed by the range of 501–1000 μg/mL (40 extracts, 22.2%). Based on IC50, the most effective plants were three species of Piper (Piper nigrum, Piper betle, and Piper chaba), followed by Nigella sativa, Psidium guajava, Syzygium cumini, C. dactylon, and Phyllanthus emblica. In addition, the toxicity of chosen extracts against normal and malignant cell lines was tested; the most effective extracts were toxic against the human lung carcinoma cell line A549, but less toxic against the human Caucasian foetal lung cell line WI26VA4. These findings suggest that some plant extracts could be employed to treat food‐borne bacterial infections, or as herbal preservatives in the food sector.

Enhancing the photocatalytic and antimicrobial activity of ZnFe2O4 by composite with Ag2WO4 semiconducting material

In this research article, we have performed the degradation of methylene blue dye (MB) in the presence of ZnFe2O4/Ag2WO4 photocatalyst. These catalyst materials are prepared by a simple combustion method followed by a solution mixing method. The structure and morphology of prepared composite material are analyzed by using XRD, FTIR, UV-DRS, and scanning electron microscopy. The antimicrobial property of composite material is studied against E. coli and S. aureus food pathogenic bacteria. After the incubation time, the antimicrobial activity of the composite material shows a clear zone of inhibition. This composite photocatalyst is a promising material to increase the degradation percentage of MB (Methylene blue) dye in the presence of UV light. ZnFe2O4/Ag2WO4 composite material shows 72.72% degradation of the MB dye. The photocatalytic activity of composite material has been performed by varying the catalyst dosage and pH level of the medium used for the degradation process. The role of composite material in the degradation of dye and their increase in the reaction rate has also been discussed. From these results, the ZnFe2O4/Ag2WO4 composite is a good material to degrade the toxic pollutants in the environment.

Antibacterial Potency of Sea Star Linckia laevigata Extract Against Selected Pathogenic Bacteria

The sea star (Asteroidea) is reported to have the potency to be a source of antimicrobial agent. An exploration study was conducted to reveal the potency of antibacterial bioactive of sea star from Maluku waters. This study aimed to determine the bioactive compounds of the Linckia laevigata extract and their antimicrobial activity. The results of qualitative phytochemical test showed that the L. laevigata extract contains flavonoid and saponin. The antimicrobial activity of the L. laevigata extract was demonstrated by an inhibition zone diameter of 29.5 mm against Enterobacter aeuregens and 22.1 mm against Clostridium botulinum. The L. laevigata extract has been proven to have antibacterial activityagainst food pathogenic bacteria.

An ultrasensitive smartphone-assisted bicolor-ratiometric fluorescence sensing platform based on a “noise purifier” for point-of-care testing of pathogenic bacteria in food

Non-specific binding in fluorescence resonance energy transfer (FRET) remains a challenge in foodborne pathogen detection, resulting in interference of high background signals. Herein, we innovatively reported a dual-mode FRET sensor based on a “noise purifier” for the ultrasensitive quantification of Escherichia coli O157:H7 in food. An efficient FRET system was constructed with polymyxin B-modified nitrogen-sulfur co-doped graphene quantum dots (N, S-GQDs@PMB) as donors and aptamer-modified yellow carbon dots (Y-CDs@Apt) as acceptors. Magnetic multi-walled carbon nanotubes (Fe@MWCNTs) were employed as a “noise purifier” to reduce the interference of the fluorescence background. Under the background purification mode, the sensitivity of the dual-mode signals of the FRET sensor has increased by an order of magnitude. Additionally, smartphone-assisted colorimetric analysis enabled point-of-care detection of E. coli O157:H7 in real samples. The developed sensing platform based on a “noise purifier” provides a promising method for ultrasensitive on-site testing of trace pathogenic bacteria in various foodstuffs.

Antagonistic Effects of Lactic Acid Bacteria Isolated from Ethiopian Traditional Fermented Foods and Beverages Against Foodborne Pathogens.

Lactic acid bacteria (LAB) found in Ethiopian traditional fermented foods and beverages have potential antagonistic effects against foodborne pathogens due to their capacity to produce various antimicrobial metabolites. This study evaluated the antagonistic activity of LAB isolated from Ethiopian traditional fermented foods and beverages against foodborne pathogens and characterized their antimicrobial substances. A total of 180 traditional fermented foods and beverages were collected, and the antagonistic activities of LAB were evaluated against selected foodborne pathogens. The effects of pH, temperature, enzymes, and food additives on the antagonistic effects of cell-free supernatant produced by LAB were investigated. LAB identification and characterization were conducted using an integrated phenotypic approach and MALDI TOF MS spectrum analysis, and data were analyzed using one-way ANOVA and Tukey post hoc analysis. A total of 956 LAB were isolated, of which seventeen (17 LAB) isolates of Pediococcus pentosaceus (Pc. pentosaceus (n = 7)), Pediococcus acidilactici (Pc. acidilactici (n = 2)), Enterococcus faecium (Ec. faecium (n = 6)), and Lactococcus lactis (Lc. lactis (n = 2)) were screened for antagonistic activity based on their ability to produce bacteriocins, probiotic activity, and preservative potential. Pc. pentosaceus JULABB16, Pc. pentosaceus JULABB01, and Ec. faecium JULABBr39 showed strong antagonistic activity against all pathogens, with mean inhibition zone diameters ranging from 23.50 to 35.50mm. Lc. lactis, Pc. pentosaceus, Pc. acidilactici, and Ec. faecium produced bioactive metabolites that were sensitive to proteolytic enzymes and capable of withstanding high temperatures (80-100°C) and acid concentrations (pH 2-10). The CFS produced by Lc. lactis, Pc. pentosaceus, Pc. acidilactici, and Ec. faecium showed the most impending antagonistic activity against all pathogens. The bioactive substances produced by LAB isolates had promising effects against food spoilage and pathogenic bacteria, making them potential natural food preservatives.

Antioxidant and antimicrobial effect of sodium alginate nanoemulsion coating enriched with oregano essential oil (Origanum vulgare L.) and Trachyspermum ammi oil (Carum cupticum) on food pathogenic bacteria.

Today, microbial contamination in food is one of the major problems of the food industry and public health in general around the world. Foodborne illnesses, such as diarrheal diseases, kill many people around the world each year. The general objective of this study was to evaluate the antioxidant and antibacterial activity of sodium alginate nanoemulsion coating incorporated with oregano essential oil (Origanum vulgare L.) and Trachyspermum ammi oil (Carum cupticum) on Escherichia coli, and Listeria monocytogenes. To achieve this study, fresh chicken meat was used for this experiment. Listeria monocytogenes ATCC 19111 and Escherichia coli ATCC 35218 were obtained from the American Type Culture Collection (Manassas, VA, USA). After the preparation of the essential oil, the chemical composition of this essential oil was determined by using (GC-MS). The physicochemical properties of the nanoemulsion essential oil prepared were characterized and their antimicrobial activity was evaluated. The results showed that the GC-MS analysis of the volatile constituents of the Origanum vulgare essential oil compounds allowed the identification of 19 compounds representing 93.72% of the total oil. The major components detected in Origanum vulgare essential oil were pulegone (49.25%), eucalyptol (18.23%), and menthone (12.37%). About the Carum cupticum essential oil, 21 compounds representing 98.5% of the total oil were identified. The major components detected in Origanum vulgare essential oil were thymol (23.3%), p-cymene (17.5%), and γ-terpinene (16.8%). The best z-average (d.nm) is 483.4 nm (Carum cupticum essential oil + nano) followed by 470.1 nm (nanochitosan). The results of the antimicrobial test showed that the different preparations have a good inhibitory activity for the invitro growth of Escherichia coli and Listeria monocytogenes. According to the MIC and MBC results of this study, the nanoemulsion also presented a good bacteriostatic activity against the two pathogenic bacteria tested in this study.

Characteristics and Antibacterial Activities of Bacteriocin Produced by Lactid Acid Bacteria Isolate LG-50 and LG-90

Biopreservative agents is natural food preservative agent derived from microbes such as bacteriocin produced by lactic acid bacteria (LAB). Bacteriocin is a protein compound that has a small molecular weight and has antibacterial activity because it is effective in preventing the growth of pathogenic bacteria in food and beverages. Escherichia coli and Staphylococcus aureus are pathogenic bacteria that can contaminate seafood products because they can cause infection and food toxication. Isolates LG-50 and LG-90 are LAB, bacterial collection of the Microbiology Laboratory, Faculty of Biology, Isolate from mangrove sediment in Logending beach. Both isolates are not yet known for their potencies to synthesize bacteriocin and its inhibitory capability to the growth E. coli and S. aureus. The research aimed to determine the ability of LG-50 and LG-90 isolates to produce bacteriocin, to determine the ability of LG-50 and LG-90 isolates to inhibit the growth of E. coli and S. aureus bacteria invitro, to identity the characteristics of isolate LG-50 and LG-90 from Logending beach mangrove sediment. The results of this research show that the bacteriocins LG-50 and LG-90 were able to inhibit the growth of E.coli with inhibition zone diameters of 13.5 mm and 13 mm, in S. aureus with inhibition zone diameters of 15 mm and 15.5 mm.

Evaluation of the antibacterial, modulatory and anti-adherent properties of oregano (Origanum vulgare) essential oil against food pathogenic bacteria

There are over 250 types of foodborne diseases, the majority of which are infections caused by bacteria. Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus saprophyticus are considered contaminants of meat products. The use of natural products as antimicrobials to combat these diseases can be an effective and economical approach. This study proposes to assess the antibacterial, modulatory, and anti-adherent activity of the essential oil of Origanum vulgare against strains of Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus saprophyticus isolated from meat products. The assay was conducted in duplicate. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined using the broth microdilution technique. MIC represents the lowest concentration of the product capable of inhibiting the growth of the bacterial strain, whereas MBC represents the lowest concentration capable of inhibiting total growth. The study of association of the product with antimicrobials was undertaken by disk diffusion using ampicillin, gentamicin, ceftazidime, and ciprofloxacin, resulting in synergistic, antagonistic, or indifferent effects. Anti-adherent activity was determined in the presence of sucrose, as the lowest concentration of the agent in contact with sucrose that prevented adherence to the glass tube. Oregano oil exhibited strong inhibitory and bactericidal activity against Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus saprophyticus, with MIC values ranging from 32 to 512 μg mL-1 and MBC values ranging from 128 to 512 μg mL-1. Origanum vulgare oil showed varied interactions when associated with antimicrobials, with modulations for synergism (37.5%), indifference (50%), and antagonism (12.5%). Regarding anti-adherent activity, the test product effectively inhibited the adherence of P. aeruginosa bacterial strains in the presence of sucrose (1:8) but had no effect against K. pneumoniae or S. saprophyticus. Therefore, oregano oil proves to be an antibacterial and modulating agent against different bacteria isolated from meat products. Additionally, it displays anti-adherent properties against P. aeruginosa, making it a natural product that could serve as an interesting alternative in efforts to combat foodborne diseases.

Antimicrobial potential of essential oil artemisia sieversiana: a medicinal plant from the high altitude nubra valley, Ladakh

Artemisia sieversiana Ehrh. ex Willd. (common name: wormwood; family: Asteraceae) is a medicinal plant thriving at high altitudes. It is extensively utilized in traditional folk medicine by various ethnic communities to alleviate and treat a wide range of health issues. However, despite its widespread use, the chemical characterization and identification of bioactive compounds responsible for these benefits is still incomplete, especially in the context of Trans−Himalayan region. Prior research has demonstrated the substantial efficacy of this plant against various pathogenic bacteria, although these studies utilized essential oil (EO) extracted from different geographic regions. There is a need for further research to explore the antibacterial activity of A. sieversiana EO from the Trans−Himalayan, Ladakh region, as the unique environmental conditions of this region may influence the plant’s chemical composition and biological activity. This research therefore focusses on characterizing the phytochemical composition and evaluating the antibacterial properties of EO extracted from A. sieversiana, specifically from the Nubra valley, Ladakh (India). The antimicrobial potential of A. sieversiana essential oil was tested against a diverse spectrum of gram-negative (Erwinia herbicola and Pseudomaonas syringae) and gram-positive bacteria (Bacillius cereus, B. pumilus, Rhodococcus fasciens, and Streptomyces scabiei) plant and food pathogenic bacteria. Gas Chromatography−Mass Spectrometry (GC−MS) analysis led to the identification of 28 components with camphor (18.8%), borneol (11.2%), and 1,8−cineole (9.7%) as the major constituents. Further, the EO was more active against gram−positive bacteria, with a greater inhibition percentage for all gram−positive bacteria (24.68%−38.90%) than for gram−negative bacteria (0%−50.19%) at 10 µg mL−1. Moreover, the antibacterial activity showed a concentration dependent response, escalating from 24.68% to complete inhibition (100%) as the EO concentration increased from 10 to 160 µg mL−1. Notably, the EO demonstrated strongest activity against B. pumilus, even more than the common antibiotic Rifampicin. Among gram−negative bacteria, Erwinia herbicola showed the highest susceptibility. This observation shows that the essential oil of A. sieversiana exhibits promising antimicrobial activity and highlighted their potential for further exploration and utilization.

Anti-bacterial activity of essential oils against multidrug-resistant foodborne pathogens isolated from raw milk.

The presence of pathogenic bacteria in food is considered as a primary cause of food-borne illness and food quality deterioration worldwide. The present study aimed to determine the effectiveness of five essential oils (EOs) against multidrug-resistant foodborne pathogens. In the current study Gram-negative bacteria (Escherichia, Enterobacter, Citrobacter, Proteus, Pseudomonas, and Klebsiella) and the Gram-positive bacteria Staphylococcus were isolated from raw milk and biochemically characterized. The anti-bacterial effect of different antibiotics and EOs (thyme, oregano, lemongrass, mint, and rosemary) was determined using the standard disc diffusion method. The antibiogram study revealed that Gram-negative bacteria were highly resistant to penicillin while Staphylococcus was resistant to streptomycin, amoxicillin, and lincomycin. Moderate resistance was observed to doxycycline, amikacin, enrofloxacin, kanamycin and cefixime. Isolates were found less resistant to gentamycin, chloramphenicol, and ciprofloxacin. EOs showed a broad range of antimicrobial activity against all bacteria except P. aeruginosa. Of these, thyme was more effective against most of the multi-drug resistant bacterial strains and formed the largest zone of inhibition (26 mm) against Escherichia followed by oregano oil (18 mm) against Staphylococcus (p<0.05). Klebsiella spp and Citrobacter spp showed resistance to mint and lemongrass oil respectively. The EOs such as lemongrass, mint and rosemary were less active against all the bacteria. The findings of the recent study suggest the use of EOs as natural antibacterial agents for food preservation.

Current state of advancements in rapid detection technology for pathogenic bacteria in food

Current state of advancements in rapid detection technology for pathogenic bacteria in food