The Inhibitory Effects of 2 Commercial Probiotic Strains on the Growth of Staphylococcus aureus and Gene Expression of Enterotoxin A

Background: Food-borne intoxications are current problems in human society and most of them are caused by the enterotoxins of Staphylococcus aureus. Staphylococcal enterotoxin A (SEA) is the most frequently responsible for staphylococcal food poisoning outbreaks. From a food safety and human health point of view, lactic acid bacteria (LAB) may provide a promising strategy to combat the pathogenic bacteria, particularly S. aureus. Objective: The objective of this study was to evaluate the inhibitory activity of two commercial lactobacillus strains on growth and enterotoxin A production by S. aureus. Moreover, the inhibitory effect of these strains on gene expression of enterotoxin type A was assessed using real-time Polymerase chain reaction (PCR). Materials and Methods: In this study the inhibitory effect of two commercial probiotic strains, Lactobacillus acidophilus (LA5) and Lactobacillus casei 01 on the growth and enterotoxin production of S. aureus was evaluated at 25 and 35°C. The gene expression of SEA of S. aureus was also evaluated by real time (RT) PCR technique. Results: The lactobacillus strains decreased the bacterial count at both temperatures compared with the control group. This reduced effect was greater at 25°C (3 log/CFU) than 35°C (2 log/CFU). The production of SEA, SEC and SEE was inhibited by the lactobacillus strains. Furthermore, the gene expression of SEA was significantly suppressed in S. aureus co cultured with studied lactobacillus strains and the greatest down-regulation of sea (10.31 fold) was observed in co-incubation of S. aureus with LC01 at 25°C. Conclusion: This research raises important implications for the potential use of LAB as a natural preservative in foodstuffs by correct microbial ecology of the environment and a new approach for biocontrol of S. aureus

Frequency and antibiotic resistance of Helicobacter pullorum among exposed and non-exposed population

Background: Helicobacter pullorum can infect the intestinal tracts of both humans and avian species. This study aimed to assess the frequency and antibiotic resistance of H. pullorum isolated from workers in the poultry slaughterhouses, farms, and markets as exposed population and healthy people who referred to the hospital as non-exposed population by culture method and polymerase chain reaction (PCR) test. Methods: Two hundred healthy individuals, including 100 individuals from exposed population and 100 from non-exposed population were selected in Semnan. Fresh stool samples were examined by conventional culture method and biochemical tests. PCR test with 16S rRNA gene was employed to confirm the H. pullorum isolates. Antibiotic resistance test was done using the disk diffusion method and various antimicrobial agents. Results: Generally, 17 (17%) samples from exposed population and 12 (12%) samples from non-exposed population were H. pullorum positive by culture method and biochemical tests. However, PCR test could confirm 10 (10%) and 7 (7%) samples from exposed and non-exposed populations, respectively. Therefore, the frequency of H. pullorum was determined to be 9.5%. Antibiotic resistance test could reveal that most of the isolates were resistant to ciprofloxacin (84.2%), whereas resistance to colistin and fosfomycin was found to be 15.8%. Conclusion: The present study illustrated that H. pullorum can be present among healthy population with the low frequency rate. Moreover, it was indicated that the frequency of this food-borne pathogen is high in the exposed population. Therefore, there is a high demand for good observation for slaughter hygiene and implementation of routine surveillance in the poultry farms and markets. Keywords: Helicobacter pullorum, Frequency, Humans, Poultry, Polymerase chain reactio

Theoretical Investigation on Antioxidant Activity of Bromophenols from the Marine Red Alga <i>Rhodomela confervoides</i>: H‑Atom vs Electron Transfer Mechanism

Bromophenols are known as antioxidant radical scavengers for some biomolecules such as those in marine red alga. Full understanding of the role played by bromophenols requires detailed knowledge of the radical scavenging activities in probable pathways, a focus of ongoing research. To gain detailed insight into two suggested pathways, H-atom transfer and electron transfer, theoretical studies employing first principle quantum mechanical calculations have been carried out on selected bromophenols. Detailed investigation of the aforementioned routes revealed that upon H-atom abstraction or the electron transfer process, bromophenols cause an increase in radical species in which the unpaired electron appears to be delocalized as much as possible over the whole aromatic ring, especially in the bromine substituent. The O–H bond dissociation energies (BDEs) and ionization potential energies (IPs) are reported at the B3LYP level of theory, providing the first complete series of BDEs and IPs for bromophenols. The observations are compared to those of other antioxidants for which BDEs and IPs have been previously obtained

Investigating and optimizing the effect of combined coating of whey protein concentrate, maltodextrin and rosemary essence on the chemical properties of tilapia fish during cold storage

polyunsaturated fatty acids, and pH. One of the methods which can control the spoilage rate is the use of natural coatings. This study aimed to investigate the effect of coating Tilapia fish fillets with whey protein concentrate (10, 15, and 20% w/w), maltodextrin (15, 20, and 25% w/w), and rosemary essential oil (1, 3 and 5% v/w). The optimization of the process was conducted by response surface methodology and Design Expert software. For this purpose, 18 models were presented by the software, and the samples were immersed in the produced solutions and were kept at 4 °C for 6 days. After this period, peroxide value (PV), Thiobarbituric acid (TBARS), Total Volatile Basic Nitrogen (TVBN), and pH were measured. The results showed that by increasing the concentration of biopolymers and essential oil, all the investigated parameters were in lower limits, and in the sample coated with the maximum concentration of substances, the values of PV, TBARS acid, TVBN, and pH (in 100 grams), were 1.05 meq, 0.05 mg, 5.7 mg and 6.2, respectively, while these values for the coated sample with minimum concentrations, were 3.44 meq, 0.305 mg, 10.85 mg and 6.79 respectively. By optimizing the production process by software, the best solution was achieved by mixing 11.214% w/w of whey protein concentrate, 25% w/w of maltodextrin, and 3.402% v/w of rosemary essential oil

Application of carrot waste extract and Lactobacillus plantarum in Alyssum homalocarpum seed gum-alginate beads to create a functional synbiotic yogurt

Abstract One of the most recent and effective methods, which is currently receiving special attention and is being developed by numerous researchers, is production of microspheres from the probiotic cells. The largest market segment for functional foods is represented by dairy products, which have been touted as the most effective carriers of nutrients, such as probiotics, prebiotics, proteins, vitamins, and minerals. Yogurt is fermented dairy product that is popular all over the world. A new functional symbiotic yogurt fabricated by plant wastes (carrot pomace extract), Lactobacillus plantarum, and beads based on Alyssum homolocarpum seed gum (AHSG) and sodium alginate (SA) using extrusion technique was produced and characterized. Evaluation of the functional properties of yogurts indicated that the total phenolic content and DPPH radical scavenging activity were in the range of 16.13–48.30 µg GAE/ml and 7.4–14.64%, respectively. The acidity, pH, syneresis, water holding capacity, lightness, redness, and yellowness of the yogurts were in the range of 1.50–2.90, 4.07–4.38, 49.00–57.24%, 46.8–57.3%, 57.16–61.25, − 0.20–0.91, 6.40–13.06 on the 28th day storage, respectively. The panelists confirmed the sensory properties of yogurt samples. Probiotic survival rate of the functional yogurts were in the range of 6.37–8.13 log CFU/g, on the 28th day. Based on the results, bead production by AHSG and SA and the use of carrot pomace extract enhanced the survival of probiotic bacteria significantly in yogurt during storage compared to free cells. Graphical Abstrac

Antimicrobial activity of Zataria multiflora boiss. essential oil on Staphylococcus aureus isolated from raw milk

Enterotoxin-producing strains of Staphylococcus aureus can cause food poisoning through the consumption of contaminated dairy products. Essential oil (EO) of Zataria multiflora Bioss. contains components with antibacterial and antifungal properties. The present study was conducted to determine the minimum inhibitory concentration (MIC) of Z. multiflora Boiss. EO on S. aureus isolated from raw milk. Extraction and gas isolation of the EO was provided and analyzed by Chromatography/mass spectrometry. A total of 84 samples of raw milk from a dairy farm in Semnan were analyzed for the presence of S. aureus. Fourteen S. aureus strains were isolated from raw milk. The chemical composition of hydrodistilled EO of Z. multiflora Boiss was analyzed by Chromatography/mass spectrometry. A total of 25 compounds representing 98.59% of the oil were identified: carvacrol (50.53%), thymol (14.7%), p-cymene (7.9%), Carvacryl acetate (3.85%) and Trans-caryophyllene (3.4%). The MIC of Z. multiflora Boiss. Using broth microdilution method, MIC of EO on all of the S. aureus isolates was estimated at 0.0001-0.004. Based on results, the EO ofZ. multiflora Boiss possesses antibacterial activity on S. aureus isolated from raw milk

Pyoderma caused by Proteus mirabilis in sheep

Abstract Pyoderma is a purulent skin infection usually caused by bacteria and can be divided into primary and secondary categories based on histology. In the present study, an 18‐month‐old female mixed breed sheep was examined for pyoderma at the injection site of the enterotoxemia vaccine. After routine bacteriology and histopathology procedures, secondary pyoderma caused by Proteus mirabilis was diagnosed. The bacterium analysed using genome sequencing and new strain called AJJ 2021 was diagnosed. This is the first report of pyoderma caused by Proteus mirabilis in sheep