Foodborne Pathogenic Microorganisms Research Articles

A novel high-level phenyllactic acid fungal producer, Kodamaea ohmeri w5 screened from fermented broad bean-chili-paste

Phenyllactic acid (PLA) is a broad-spectrum and efficient antimicrobial phenolic acid with potential applications in the food industry. Previous studies have demonstrated that fungi may be ideal producers of PLA. In this study, 15 fungi screened from Doubanjiang with the ability to produce PLA were first reported, including Wickerhamomyces anomalus, Candida etchellsii, Candida parasitosis, Pichia kudriavzevii, Pichia membranifaciens and Kodamaea ohmeri. Among them, K. ohmeri w5 had the highest PLA yield, producing up to 7160 mg/L PLA in shake flask fermentation with phenylalanine as substrate, which was more than ten times higher than the PLA produced by wild-type LAB under the similar conditions. In addition, K. ohmeri w5 was able to grow under extreme hypertonic conditions of 20 % NaCl (w/v) and 50 % glucose (w/v) as well as produce 57.12 ± 0.42 and 1609.22 ± 36.26 mg/L of PLA, respectively. Furthermore, the fermentation supernatant of K. ohmeri w5 demonstrated direct inhibitory effects against foodborne pathogenic microorganisms, Aspergillus flavus and Bacillus cereus. However, the inhibitory effect was weaker than that of the PLA standard at the same concentration. Further, 12,497,932 bp of w5 genome-wide information was obtained by sequencing and assembling. And its gene model was predicted based on transcriptomic evidence, which showed that a total of 7 genes related to PLA synthesis were identified in the w5 genome. Based on qRT-PCR, structure prediction, and molecular docking, a potentially key genetic resource from K. ohmeri w5 for PLA production was uncovered. The results will provide novel producers of PLA and its potential genetic resources.

Antimicrobial activity of magnolol against Bacillus cereus and its application as food preservative

The aim of this study was to explore the antibacterial properties and mechanism of magnolol against Bacillus cereus. Our findings demonstrated that magnolol exhibited potent antimicrobial activity against B. cereus, with minimum inhibitory concentrations (MICs) of 2 μg/mL. Additionally, magnolol could inhibit spore germination and biofilm formation in a dose-dependent manner. Electron microscopy and membrane potential analysis indicated that the cytomembranes were disrupted, resulting in leakage of cellular contents. Transcriptomic profiling showed that magnolol treatment (1/2 × MIC) resulted in 585 differentially expressed genes (DEGs), including 295 down-regulated and 290 up-regulated genes. Bioinformatic analysis indicated that magnolol affected many potential cellular responses, including cellular metabolic process, locomotion, oxidative stress, and cell membranes. The pathway analysis revealed that DEGs mainly associated with flagellar assembly, bacterial chemotaxis, amino acids, and energy metabolism. Moreover, magnolol obviously reduced the amount of B. cereus in boiled rice and beef at 4 °C storage. These results provided insights into the molecular mechanism of magnolol against B. cereus and suggested that magnolol might be a promising natural antimicrobial agent for controlling the B. cereus in foods. Industrial relevanceBacillus cereus is considered as an important foodborne pathogenic microorganism that can exist as vegetative cells, spores, and biofilm in various food-processing environment, posing a big challenge for the food industry. Magnolol is a natural compound with potent antimicrobial activity against various pathogens and has been certified as safe by food safety organizations. Consequently, magnolol holds great promise as a natural antimicrobial agent for controlling B. cereus contaminations in foods.

A multiplex method for the detection of food microorganisms based on suspension microarrays combined with recombinase-aided amplification

Foodborne diseases caused by foodborne pathogenic microorganisms have long been a severe public health problem. Timely and accurate detection of food-borne microorganisms can minimize their harm and enable the development of efficient control strategies. In this study, we establish a multiplex nucleic acid detection method based on recombinase-aided amplification reaction on a suspension microarray (referred to as SC-RAA) to identify and quantify microorganisms. The experimental results confirmed that this approach has an outstanding sensitivity, with a limit of detection (LOD) of 0.8 fM and a linear range of 0.8 fM–80 pM, spanning five orders of magnitude. Moreover, the prepared method also showed exquisite specificity, which the amplified signal can be detected only when the target nucleic acid is present. The recovery rate of the SC-RAA assay was 82.2%–113.4%, suggesting that the SC-RAA assay is performing well and accurately measuring the concentration of the substance in the sample. In addition, the consistency analysis showed that the results of the SC-RAA detection were also in good agreement with those of traditional qPCR detection (R2 > 0.95). These results highlight the potential of the SC-RAA assay to be applied as a multiplex and sensitive DNA detection platform for identifying and quantifying foodborne pathogenic microorganisms.

A Dual-mode platform for the rapid detection of Escherichia coli O157:H7 based on CRISPR/Cas12a and RPA.

Escherichia coli O157:H7 (E. coli O157:H7) is a foodborne pathogenic microorganism that is commonly found in the environment and poses a significant threat to human health, public safety, and economic stability worldwide. Thus, early detection is essential for E. coli O157:H7 control. In recent years, a series of E. coli O157:H7 detection methods have been developed, but the sensitivity and portability of the methods still need improvement. Therefore, in this study, a rapid and efficient testing platform based on theCRISPR/Cas12a cleavage reaction was constructed. Through the integration of recombinant polymerase amplification and lateral flow chromatography, we established a dual-interpretation-mode detection platform based on CRISPR/Cas12a-derived fluorescence and lateral flow chromatography for the detection of E. coli O157:H7. For the fluorescence detection method, the limits of detection (LODs) of genomic DNA and E. coli O157:H7 were 1.8fg/µL and 2.4CFU/mL, respectively, within 40min. Conversely, for the lateral flow detection method, LODs of 1.8fg/µL and 2.4 × 102CFU/mL were achieved for genomic DNA and E. coli O157:H7, respectively, within 45min. This detection strategy offered higher sensitivity and lower equipment requirements than industry standards. In conclusion, the established platform showed excellent specificity and strong universality. Modifying the target gene and its primers can broaden the platform's applicability to detect various other foodborne pathogens.

Polyphenolic compounds in the combat of foodborne infections - An update on recent evidence.

In recent years, the incidence of food-borne bacterial enteric diseases has increased worldwide causing significant health care and socioeconomic burdens. According to the World Health Organization, there are an estimated 600 million cases of foodborne illnesses worldwide each year, resulting in 420,000 deaths. Despite intensive efforts to tackle this problem, foodborne pathogenic microorganisms continue to be spread further. Therefore, there is an urgent need to find novel anti-microbial non-toxic compounds for food preservation. One way to tackle this issue may be the usage of polyphenols, which have received increasing attention in the recent years given their pleotropic health-promoting properties. This prompted us to perform a literature search summarizing studies from the past 10 years regarding the potential anti-microbial and disease-alleviating effects of plant-derived phenolic compounds against foodborne bacterial pathogens. The included 16 studies provide evidence that polyphenols show pronounced anti-bacterial and anti-oxidant effects against both Gram-positive and Gram-negative bacterial species. In addition, synergistic anti-microbial effects in combination with synthetic antibiotics were observed. In conclusion, phenolic compounds may be useful as natural anti-microbial agents in the food, agricultural, and pharmaceutical industries in the combat of foodborne infections.

Antimicrobial Activity of Caesalpinia pulcherrima (L.) Leaves Extracts against Food Borne Pathogenic and Spoilage Microorganisms

With continuous increase in the human population, the cases of food poisoning and spoilage are on the rise. Such spoilage of foods to avoid the growth of unwanted microorganisms in order to protect from poisoning is generally achieved by the use of preservatives. But due to continuous exposure of the microorganism with the same preservatives have been resulted to create resistance against it. So, in order to search for the new preservatives, the petroleum ether, chloroform, acetone, methanol and aqueous extracts of Caesalpinia pulcherrima (L.) leaves have been examined against Bacillus cereus, Escherichia coli and Aspergillus niger HN-2 microorganisms for antimicrobial activity. The conducted experimental results clearly indicated about its ability to restrict the growth of tested microorganisms generally responsible for food poisoning and spoilage. Since, the previous reported toxicity studies already showed its safety profile, these plant extracts can surely be the matter of alternative choice as food preservatives.

Food-borne bacteria analysis using a diatomite bioinspired SERS platform.

Rapid and sensitive detection of food-borne bacteria has remained challenging over the past few decades. We propose a surface-enhanced Raman scattering sensing strategy based on a novel bioinspired surface-enhanced Raman scattering substrate, which can directly detect dye molecular residues and food-borne pathogen microorganisms in the environment. The surface-enhanced Raman scattering platform consists of a natural diatomite microporous array decorated with a metal-phenolic network that enables the in situ reduction of gold nanoparticles. The as-prepared nanocomposites display excellent surface-enhanced Raman scattering activity with the lowest limit of detection and the maximum Raman enhancement factor of dye molecules up to 10-11 M and 1.18 × 107, respectively. For food-borne bacterial detection, a diatomite microporous array decorated with a metal polyphenol network and gold nanoparticle-based surface-enhanced Raman scattering analysis is capable of distinguishing the biochemical fingerprint information of Staphylococcus aureus and Escherichia coli, indicating the great potential for strain identification.

CRISPR/Cas-based colorimetric biosensors: a promising tool for the diagnosis of bacterial foodborne pathogens in food products.

Some physical phenomena and various chemical substances newly introduced in nanotechnology have allowed scientists to develop valuable devices in the field of food sciences. Regarding such progress, the identification of foodborne pathogenic microorganisms is an imperative subject nowadays. These bacterial species have been found to cause severe health impacts after food ingestion and can result in high mortality in acute cases. The rapid detection of foodborne bacterial species at low concentrations is in high demand in recent diagnostics. CRISPR/Cas-mediated biosensors possess the potential to overcome several challenges in classical assays such as complex pretreatments, long turnaround time, and insensitivity. Among them, colorimetric nanoprobes based on the CRISPR strategy afford promising devices for POCT (point-of-care testing) since they can be visualized with the naked eye and do not require diagnostic apparatus. In this study, we briefly classify and discuss the working principles of the different CRISPR/Cas protein agents that have been employed in biosensors so far. We assess the current status of the CRISPR system, specifically focusing on colorimetric biosensing platforms. We discuss the utilization of each Cas effector in the detection of foodborne pathogens and examine the restrictions of the existing technology. The challenges and future opportunities are also indicated and addressed.

Foodborne Pathogen and Microbial Community Differences in Fresh Processing Tomatoes in Xinjiang, China.

The microbes on fresh processing tomatoes correlate closely with diseases, preservation, and quality control. Investigation of the microbial communities on processing tomatoes from different production regions may help define microbial specificity, inform disease prevention methods, and improve quality. In this study, surface microbes on processing tomatoes from 10 samples in two primary production areas of southern and northern Xinjiang were investigated by sequencing fungal internal transcribed spacer and bacterial 16S rRNA hypervariable sequences. A total of 133 different fungal and bacterial taxonomies were obtained from processing tomatoes in the two regions, of which 63 genera were predominant. Bacterial and fungal communities differed significantly between southern and northern Xinjiang, and fungal diversity was higher in southern Xinjiang. Alternaria and Cladosporium on processing tomatoes in southern Xinjiang were associated with plant pathogenic risk. The plant pathogenic fungi of processing tomatoes in northern Xinjiang were more abundant in Alternaria and Fusarium. The abundance of Alternaria on processing tomatoes was higher in four regions of northern Xinjiang, indicating that there is a greater risk of plant pathogenicity in these areas. Processing tomatoes in northern and southern Xinjiang contained bacterial genera identified as gut microbes, such as Pantoea, Erwinia, Enterobacter, Enterococcus, and Serratia, indicating the potential risk of contamination of processing tomatoes with foodborne pathogens. This study highlighted the microbial specificity of processing tomatoes in two tomato production regions, providing a basis for further investigation and screening for foodborne pathogenic microorganisms.

Isothermal Amplification and CRISPR/Cas12a-System-Based Assay for Rapid, Sensitive and Visual Detection of Staphylococcus aureus.

Staphylococcus aureus exists widely in the natural environment and is one of the main food-borne pathogenic microorganisms causing human bacteremia. For safe food management, a rapid, high-specificity, sensitive method for the detection of S. aureus should be developed. In this study, a platform for detecting S. aureus (nuc gene) based on isothermal amplification (loop-mediated isothermal amplification-LAMP, recombinase polymerase amplification-RPA) and the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas12a) proteins system (LAMP, RPA-CRISPR/Cas12a) was proposed. In this study, the LAMP, RPA-CRISPR/Cas12a detection platform and immunochromatographic test strip (ICS) were combined to achieve a low-cost, simple and visualized detection of S. aureus. The limit of visual detection was 57.8 fg/µL of nuc DNA and 6.7 × 102 CFU/mL of bacteria. Moreover, the platform could be combined with fluorescence detection, namely LAMP, RPA-CRISPR/Cas12a-flu, to establish a rapid and highly sensitive method for the detection of S. aureus. The limit of fluorescence detection was 5.78 fg/µL of genomic DNA and 67 CFU/mL of S. aureus. In addition, this detection platform can detect S. aureus in dairy products, and the detection time was ~40 min. Consequently, the isothermal amplification CRISPR/Cas12a platform is a useful tool for the rapid and sensitive detection of S. aureus in food.

The survival and enterotoxin gene expression of Staphylococcus aureus planktonic and biofilm cells in quick-frozen food

Food safety issues caused by food-borne pathogenic microorganisms during low-temperature food storage have attracted broad attention. In the current study, Staphylococcus aureus cells in planktonic and different stages of biofilm formation were inoculated into four types of quick-frozen rice and flour products. The changes in culturable cell number of S. aureus in the artificially contaminated food samples stored at 4 °C and −20 °C were recorded for 60 days. Next, the PMA-qPCR method was used to explore the viable cell number and determine whether low temperature induced S. aureus enter into the viable but non-culturable (VBNC) state. Finally, the expression changes of enterotoxin gene seb in S. aureus were determined by RT-qPCR during food sample storage. Results showed that the culturable cell number of S. aureus was not significantly changed during 60 days except for the decreased culturable cell number in the 8 h biofilm cells in MF stored at −20 °C. In addition, S. aureus cells did not enter into the VBNC state during low temperature storage. Moreover, the seb gene was continuously expressed in most samples although with difference in expression level. The findings provided an alert for the risk of S. aureus contamination in quick-frozen rice and flour products.

Germicidal effect of intense pulsed light on Pseudomonas aeruginosa in food processing.

Pseudomonas aeruginosa (P. aeruginosa) can cause serious infections in many parts of the body and is also an underestimated foodborne pathogen. Intense pulsed light sterilization is recognized for its high sterilization efficiency, flexible and safe operation and ease of installation on production lines, which makes up for the shortcomings of several other physical sterilization technologies. This experiment studied the killing efficiency of different capacitances (650 μF, 470 μF, and 220 μF) of intense pulsed light on foodborne pathogenic microorganisms P. aeruginosa in the models of liquid food models, 96-well cell plates, and polycarbonate membrane models at room temperature (25°C) and refrigerated (4°C) environments to provide data to support the application of IPL sterilization devices in food processing. The IPL was very effective in killing P. aeruginosa in the planktonic state as well as in the early and mature biofilm states, meeting target kill rates of 100%, 99.99%, and 94.33% for a given number of exposures. The biofilms formed in the polycarbonate membrane model and the 96-well plate model were more resistant to killing compared to the planktonic state. To achieve the same bactericidal effect, the number of flashes increased with decreasing capacitance. The bactericidal effect of IPL on P. aeruginosa was significantly influenced by the state of the bacterium. The larger the capacitance the higher the number of pulses and the better the sterilization effect on P. aeruginosa.

Biodegradable composites from poly(butylene adipate-co-terephthalate) with carbon nanoparticles: Preparation, characterization and performances

The development of composites for food packaging that have good mechanical and antimicrobial characteristics is still a major challenge. In applications like food packaging, the usage of poly (butylene adipate-co-terephthalate) (PBAT), which has an adversative effect on the environment and reduces petroleum resources, has grown widespread. The present work reveals PBAT composites reinforced with CNPs at a few percentages up to 5.0 wt %. The PBAT/CNPs composites were produced using the solvent casting method. The results of TGA studies, CNPs significantly enhanced the thermal stability of composites using PBAT. The mechanical strength of the PBAT composites was improved by increasing CNPs concentration. Tensile strength increased from 7.38 to 10.22 MPa, respectively. The oxygen transmission rate (OTR) decreased with increasing the CNPs concentrations. The barrier properties (H2O and O2) of PBAT were improved by the presence of CNPs. WVTR was calculated to be 108.6 ± 1.8 g/m2/day for PBAT. WVTR reduced when CNPs concentration in PBAT increased. The PCN-5.0 film sample had the lowest WVTR value, 34.1 ± 3.1 g/m2/day. For PCN-3.0, WVTR dropped by 45.39%, indicating and even with a 3.0 wt% loading of CNPs in PBAT, the rise is noticeable. Contact angle measurements indicate that PBAT/CNPs composites becomes hydrophobic after reinforcing. Gram-positive (S. aureus) and Gram-negative (E. coli) food-borne pathogenic microorganisms showed enhanced antimicrobial activity against the developed PBAT composites. The carrot pieces preserved their freshness for an extended period of 12 days while packaged in the PBAT/CNPs composite film, indicating that the film is an effective and excellent packaging for food materials.

Fusarium Mycotoxins Zearalenone and Deoxynivalenol Reduce Hepatocyte Innate Immune Response after the Listeria monocytogenes Infection by Inhibiting the TLR2/NFκB Signaling Pathway.

Zearalenone (ZEA) and deoxynivalenol (DON) are two common mycotoxins produced by the genus Fusarium and have potential immunotoxic effects that may lead to a weak immune response against bacterial infections. Listeria monocytogenes (L. monocytogenes), a food-borne pathogenic microorganism ubiquitous in the environment, actively multiplies in the liver, where hepatocytes are capable of resistance through mediated innate immune responses. At present, it is not clear if ZEA and DON affect hepatocyte immune responses to L. monocytogenes infection or the mechanisms involved. Therefore, in this study, in vivo and in vitro models were used to investigate the effects of ZEA and DON on the innate immune responses of hepatocytes and related molecules after L. monocytogenes infection. In vivo studies revealed that ZEA and DON inhibited the toll-like receptors 2 (TLR2)/nuclear factor kappa-B (NFκB) pathway in the liver tissue of L. monocytogenes-infected mice, downregulating the expression levels of Nitric oxide (NO), in the liver and repressing the immune response. In addition, ZEA and DON inhibited Lipoteichoic acid (LTA)-induced expression of TLR2 and myeloid differentiation factor 88 (MyD88) in Buffalo Rat Liver (BRL 3A) cells in vitro, downregulating the TLR2/NFκB signaling pathway and resulting in the decreased expression levels of NO, causing immunosuppressive effects. In summary, ZEA and DON can negatively regulate NO levels through TLR2/NFκB, inhibiting the innate immune responses of the liver, and aggravate L. monocytogenes infections in mouse livers.

Tannic acid as a crosslinking agent in poly(butylene adipate-co-terephthalate) composite films enhanced with carbon nanoparticles: Processing, characterization, and antimicrobial activities for food packaging

The disposal of plastics waste is currently a major environmental problem. Plastics are used frequently and in more variety in everyday life, which has an effect on the environment. As a result of the emissions of carbon dioxide caused by burning of non-biodegradable polymers like polyethylene, polypropylene, and polyvinyl chloride, there is a growing concern of a global warming. This article discusses the carbonization and activation of KOH to produce porous carbon nanoparticles (CNPs). The solution casting method was used to produced composites of poly(butylene adipate-co-terephthalate (PBAT) with CNPs and tannic acid (TA). PBAT composites employing CNPs as reinforcement and TA as a cross-linker. TA and CNPs have been taken into account in investigating the morphological and antimicrobial activities of PBAT-based composites. The mechanical strength of PBAT/TA/CNPs composites increased as a result to the strengthening characteristics of CNPs. The thermal characterization of PBAT/TA/CNPs composites was improved with TA and CNPs, based on thermogravimetric analysis (TGA). Contact angle measurements show that after reinforcement, PBAT/TA/CNPs composites became hydrophobic. In PBAT/TA/CNPs composites, the oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) are reduced. The PBAT/TA/CNPs composites showed greater antimicrobial activity against the food-borne pathogenic microorganisms E. coli and S. aureus. Also, the results of food quality tests that PBAT/TA/CNPs composites used to have an improved shelf life for sliced carrot than control, commercial and PBAT film extending it from 1 to 12 days. The results indicated that PBAT/TA/CNPs composites would be suitable choices for materials to be used in food packaging.

High-throughput and specific detection of microorganisms by intelligent modular fluorescent photoelectric microbe detector

Food safety has emerged as a major global issue. Detecting foodborne pathogenic microorganisms and controlling them is vital to guard against foodborne diseases caused by microorganisms. However, the current detection methods need to meet the demand for real-time detection on the spot after a simple operation. Considering unresolved challenges, we developed an Intelligent Modular Fluorescent Photoelectric Microbe (IMFP) system containing a special detection reagent. This IMFP system can automatically monitor microbial growth in which the photoelectric detection, temperature control, fluorescent probe, and bioinformatics screen are integrated into one platform and employed to detect pathogenic microorganisms. Moreover, a specific culture medium was also developed, which matched the system platform for Coliform bacteria and Salmonella typhi. The developed IMFP system could attain a limit of detection (LOD) of about 1 CFU/mL for both bacteria, while the selectivity could reach 99%. In addition, the IMFP system was applied to detect 256 bacterial samples simultaneously. This platform reflects the high-throughput needs of fields for microbial identification and related requirements, such as the development of pathogenic microbial diagnostic reagents, antibacterial sterilization performance tests, and microbial growth kinetics. The IMFP system also confirmed the other merits, such as high sensitivity, high-throughput, and operation simplicity compared to conventional methods, and it has a high potential as a tool for application in the health and food security fields.

Global gene-mining strategy for searching nonribosomal peptides as antimicrobial agents from microbial sources

Foodborne pathogenic microorganism contamination and the emergence of drug-resistant bacteria are serious threats to human public health, and cationic nonribosomal peptides (CNRPs) represent a potential solution to this threat. In this report, a global gene mining strategy was used to evaluate 6563 bacterial genomes, including Bacillus sp, Paenibacillus sp and Brevibacillus sp. Using antiSMASH with a Python script filter, we discovered that the Bacillus subtilis group, Paenibacillus polymyxa, Brevibacillus laterosporus and Brevibacillus brevis most likely produce a larger number and greater variety of CNRPs than other Bacilli bacteria. Amino acids lysine, ornithine, 2,4-diaminobutyric acid, leucine, valine, threonine and serine were incorporated in higher abundance (amino acid preference) into these antimicrobial NRPs. Furthermore, flat colony counting, acid-base titrations and Ubbelohde viscometry measurements indicated that brevilaterins from Brevibacillus laterosporus inhibited the growth of various microbes during the first four days and showed exceptional antimicrobial activity against various microbial contaminations in raw milk. Raw milk containing brevilaterins maintained its initial acidity and viscosity over two days. This study should facilitate the identification of new antimicrobial peptides derived from bacteria and their artificial design and modification, allowing those suitable microorganisms identified to be fully utilized in antimicrobial agent production and food industry applications.

Identification, Typing and Drug Resistance of Cronobacter spp. in Powdered Infant Formula and Processing Environment.

Cronobacter spp. is a food-borne pathogenic microorganism that can cause serious diseases such as meningitis, sepsis, and necrotizing colitis in infants and young children. Powdered infant formula (PIF) is one of the main contamination routes, in which the processing environment is an important source of pollution. In this investigation, 35 Cronobacter strains isolated from PIF and its processing environment were identified and typed by 16S rRNA sequencing and multilocus sequence typing (MLST) technology. A total of 35 sequence types were obtained, and three new sequence types were isolated for the first time. The antibiotic resistance was analyzed, showing that all isolates were resistant to erythromycin but sensitive to ciprofloxacin. Multi-drug resistant strains accounted for 68.57% of the total, among which Cronobacter strains with the strongest drug resistance reached 13 multiple drug resistance. Combined with transcriptomics, 77 differentially expressed genes related to drug resistance were identified. The metabolic pathways were deeply excavated, and under the stimulation of antibiotic conditions, Cronobacter strains can activate the multidrug efflux system by regulating the expression of chemotaxis-related genes, thus, secreting more drug efflux proteins to enhance drug resistance. The study of drug resistance of Cronobacter and its mechanism has important public health significance for the rational selection of existing antibacterial drugs, the development of new antibacterial drugs to reduce the occurrence of bacterial resistance, and the control and treatment of infections caused by Cronobacter.

Molecular Identification of Bacteria Isolated from Marketed Sparus aurata and Penaeus indicus Sea Products: Antibiotic Resistance Profiling and Evaluation of Biofilm Formation.

Marketed fish and shellfish are a source of multidrug-resistant and biofilm-forming foodborne pathogenic microorganisms. Bacteria isolated from Sparus aurata and Penaeus indicus collected from a local market in Hail region (Saudi Arabia) were isolated on selective and chromogenic media and identified by using 16S RNA sequencing technique. The exoenzyme production and the antibiotic susceptibility patterns of all identified bacteria were also tested. All identified bacteria were tested for their ability to form biofilm by using both qualitative and quantitative assays. Using 16S RNA sequencing method, eight genera were identified dominated by Vibrio (42.85%), Aeromonas (23.80%), and Photobacterium (9.52%). The dominant species were V. natrigens (23.8%) and A. veronii (23.80%). All the identified strains were able to produce several exoenzymes (amylases, gelatinase, haemolysins, lecithinase, DNase, lipase, and caseinase). All tested bacteria were multidrug-resistant with a high value of the multiple antibiotic index (MARI). The antibiotic resistance index (ARI) was about 0.542 for Vibrio spp. and 0.553 for Aeromonas spp. On Congo red agar, six morphotypes were obtained, and 33.33% were slime-positive bacteria. Almost all tested microorganisms were able to form a biofilm on glass tube. Using the crystal violet technique, the tested bacteria were able to form a biofilm on glass, plastic, and polystyrene abiotic surfaces with different magnitude. Our findings suggest that marketed S. aurata and P. indicus harbor various bacteria with human interest that are able to produce several related-virulence factors.

Antibacterial activity of cinnamon oil against multidrug-resistant Salmonellaserotypes and anti-quorum sensing potential

The antimicrobial resistance due to Salmonella and other foodborne pathogenic microorganisms, witnessed in recent years, has become a significant health concern. Bacteria use chemical signals to communicate each other and regulate their behavior including virulence. Depending increased antibiotic resistance, new drug development strategies being investigating and the usability of active ingredients of various medicinal and aromatic plants is especially tested as an alternative. The aim of this study was to determine the anti-quorum sensing (QS) activity of cinnamon oil (CO) on pigment production of Chromobacterium violaceum and to evaluate antibacterial activity against multidrug resistant (MDR) S. enterica serotypes. Anti QS activity was tested using biosensor strain and antibacterial activity was determined by microdilution method according to EUCAST standards. CO was found effective on QS mechanisms of Chromobacterium violaceum with pigment inhibition. Nineteen foodborne pathogens isolated from different poultry/cow sourced foods and serotyped as S. enterica serovar Infantis (15), Kentucky (1), Newport (1), Telaviv (1), and Typhimurium (1). S. enterica Infantis strains were found resistant to three or more antibiotics and categorized as MDR. The results concluded that CO has strong antibacterial activity against all S. enterica serotypes with MIC between 0.125 µg ml-1 and 1.0 µg ml-1. This research demonstrates CO is a potential candidate for developing new antimicrobial agents, antiseptic solutions or natural food preservatives against MDR Salmonella isolates also a potential as an anti-QS agent.