جستجوی مقالات مرتبط با کلیدواژه "نیسین" در نشریات گروه "دامپزشکی"

Globally, clinical mastitis (CM) is a significant disease in the dairy industry and has a tremendous economic impact because of the significantly reduced amount of milk production. Antibiotics are medicines used to treat infections, particularly those of bacterial origin. Misusing these common drugs leads to emerging resistance bacteria and public health concerns in human and animal medicine worldwide. Therefore, the use of natural alternatives with low effects is recommended. This article aims to evaluate the antibacterial activity of peptide nisin on mastitis bacteria and its synergistic effect with CLF36 peptide in vitro. Recombinant peptide nisin and CLF36 were obtained from previous research. The minimum inhibitory concentration (MIC) test was performed using the microdilution method on bacteria extracted from animal mastitis, such as Clostridium perfringens, Proteus mirabilis, Enterococcus faecalis, Salmonella typhimurium, Pseudomonas aeruginosa, and Listeria monocytogenes. This study showed that nisin and CLF36 alone had an inhibitory effect on all the studied bacteria in the 64-32 and 256-32 μg/ml concentration range, respectively. Also, the combination of nisin and CLF36 showed a general synergistic interaction for all used strains (FIC I < 0.5). This study demonstrated that combining these two peptides could reduce the risk of developing drug resistance by creating synergistic effects with a minimum concentration of each of the two peptides.

Staphylococcus aureus is a food pathogen and is a serious threat to humans. This study was conducted in order to evaluate the antibacterial effects of Hibiscus sabdariffa in inhibiting Staphylococcus aureus bacteria alone and together with nisin in Vanami shrimp minced meat. The plant was extracted using a vacuum evaporation method with the help of a rotary machine. The effect of different concentrations of alcoholic extract of Hibiscus sabdariffa (0, 1, 2.5, 3.5, 5%) and nisin (0, 0.5, 2.5 micrograms/gram) and the combination of different amounts of nisin (micrograms per gram) and extract (%) (0.25+3.5), (0.25+5), (0.5+1), (2.5+1), (2.5+2.5) were investigated on the growth behavior of the bacteria at a 4°C during 21 days. The results showed that bacterial growth in low concentrations of Hibiscus sabdariffa extract (2.5.1%) had no significant difference in inhibiting bacterial growth. Combined treatments of the extract with nisin could stop the growth of bacteria from the 6th day onwards. According to the findings of this research, it can be suggested that Hibiscus sabdariffa extract and nisin have inhibitory effects and are introduced as a natural food preservative instead of its chemical and industrial types. The combined use of these compounds proved their synergistic effects.

Staphylococcus aureus beyond the cause of food poisoning, can cause wide spectrum of infections in human and is a serious threat in food industry. This study was conducted to evaluate antibacterial effect of alcoholic extract of garlic (Allium sativum) alone and in combination with nisin on inhibition of Staphylococcus aureus in minced meat of the tilapia fish. Garlic Extract was prepared by vacuum evaporation method using the rotary device. The effects of different concentrations of garlic alcoholic extract (0, 1, 2.5, 3.5, 5%) and nisin (0, 0.5 and 2.5 μg / g) and the combinations of nisin (micrograms per gram) and Extract (%) (0.25+3.5), (0.25+5), (0.5+1), (0.5+2.5), (2.5+1), (2.5+2.5) were studied on the growth of the S. aureus at 4 ° C for 21 days. The results showed that the bacterial growth was stopped at 3.5% and 5% concentrations of garlic extract from days 12 and 9 respectively, and It was stopped at 0.5, 2.5 μg/g of nisin from days 9 and 6 respectively. Low concentrations of garlic extract (1 and 2.5%) did not inhibit the growth of bacteria. Combined treatments of extract and nisin were able to stop bacterial growth from day 6 onwards. According to this study, garlic extract and nisin have inhibitory effect on growth of bacteria and they are introduced as a natural preservative of food instead of chemical preservative. This research approved the synergistic effect of nisin and alcoholic extract on the inhibition of the S. aureus growth.

Alicyclobacillus acidoterrestris (A. acidoterrestris) is a thermophilic spore-forming bacterium that changes taste and smell of juices. The aim of this study was to investigate the inhibitory effect of nisin and ascorbic acid on A. acidoterrestris. Nisin (150 and 200 ppm) and ascorbic acid (100 and 250 ppm) were used in orange juice contaminated with A. acidoterrestris. Microbial, physicochemical, and sensory properties of the samples were investigated during 90 days’ storage. Adding nisin and ascorbic acid significantly (P<0.05) decreased the number of A. acidoterrestris in orange juice. The sample containing 200 ppm nisin+250 ppm ascorbic acid and the sample containing 200 ppm nisin+100 ppm ascorbic acid had the lowest number of A. acidoterrestris, respectively. During storage, the number of bacteria in samples containing nisin and ascorbic acid decreased significantly (P<0.05) so that no bacterial growth was seen in the sample containing 200 ppm nisin and 250 ppm ascorbic acid on the 60th and 90th days and the sample containing 200 ppm nisin+100 ppm ascorbic acid on the 90th day. Acidity of the samples increased and brix decreased significantly (P<0.05) during storage. The sample containing 150 ppm nisin +100 ppm ascorbic acid and the sample containing 200 ppm nisin +100 ppm ascorbic acid had the highest score of overall acceptance. The sample containing 200 ppm nisin +100 ppm ascorbic acid was selected as the best sample with regard to microbial and sensory properties. Therefore, orange juice containing nisin and ascorbic acid has suitable sensory quality and can affect the inhibition of A. acidoterrestris.

Effect of nisin on microbial quality of farmed great sturgeon Huso huso in refrigerator and freezing temperaturesIn this study the effects of nisin (a biotic preservative) (0, 0.2 and 0.4%) on the microbiological quality of farmed great sturgeon (H. huso) slices inoculated by Staphylococcus aureus and Escherichia coli (8 log cfu/ml) during storage (4 and -18 °C) for 10 days was determined. The counts of S. aureus did not change significantly after ten days of storage (P> 0.05) and in other words, it was not affected from different concentrations of nisin and storage temperatures. Frozen samples treated by nisin showed lower counts of E. coli. Nisin at both concentrations had the same effects on reducing the counts of both bacteria. The positive effects of such a low-risk biological preservative in studied food product appearing to reduce the microbial load, therefor its usage in preservation of food is industrially preferable rather than other chemical preservatives.

In order to prevent or inhibit the growth of pathogenic objects and factors of food spoilage, great deal of research has been done by using natural preservatives and currently is performed. This study has been done to investigate the effect of different concentrations of lysozyme and nisin on the growth rate of the bacteria Escherichia coli and Listeria monocytogenes and also  determination of MIC and MBC of this combinations on these bacteria.In this study, various concentrations of lysozyme and nisin was set in form of alone concentration and in combination concentration (0, 19.53, 39.06, 78.13, 156.25, 312.5, 625, 1250, 2500, 5000) in vitro conditions and pH 5.5, 6, 6.5, 7, 7.5 and 8.These actions was done in microdilution method at 24 ° C and reading the combined effect on the growth of bacteria was performed by using ELISA reader.The results showed that lysozyme is less effective on the E. coli and nisin have less effective on the L.monocytogenes. The combined use of lysozyme and nisin at low pH was decreased MIC.

Listeria monosytogenes is one of food borne pathogens that presence in raw foods and capable of growth during cold storage and cause infection in consumers. Raw milk is one of the most particular foods associated with listeria contamination. Reemerging listerial infection increased because of increase the consumer interest to consume of raw milk in last years. This study was conducted to evaluate the anti-listerial effect of nisin, rosemary extract and mixed of them in milk at refrigerator temperature (4±1ºC). Five treatments of milk were prepared; control sample with no nisin and rosemary extract (A), milk contain 0.5% rosemary extract (B), milk contain 1% rosemary extract (C), milk contain 1000 IU nisin (D) and milk contain 0.5% rosemary extract 500 IU nisin (E). 107 cfu/ml Listeria monosytogenes was inoculated in each sample. All samples were exanimate for Listeria monosytogenes count on day 0, 1, 2, 3, 4 and 5. Based on results; rosemary extract and nisin reduced the listerial growth. Highest anti-listerial activity was shown in sample E, D and C respectively. The antimicrobial effect of rosemary extract at high concentration significantly (p

Considering the side effects of chemical preservatives and attention of food producers to natural preservatives، evaluation of antimicrobial effects of them in the laboratory and food models seems to be necessary. Meat microbial control from health human and high quality life chief very important. Nisin has a wide spectrum inhibitory effect than the other Bacteriocins and inhibits food-borne pathogens such as S. aureus and many other Gram-positive spoilage microorganisms. The purpose of this study is investigating the effects of nisin، on the growth of S. aureus in minced sheep during refrigerated storage. Lamb mince samples were inoculated with Staphylococcus aureus ATCC 29213 1×103. Nisin treatments at three levels 5،7،9 µg/ml. Parameters included total count، Staphylococcus aureus، pH، on days 1، 3، 7، 14 Evaluation. Results showed that the effect of different concentrations of nisin was statistically significant (P< 0. 05). The antibacterial activity of nisin decreased during the storage period.

In this study، effect of different concentrations of nisin (0، 0. 25، 0. 5 and 0. 75 µg/ ml) were conducted against zoonotic bacteria Streptococcus iniae and Lactococcusgarvieae in fish fillet of rainbow trout (Oncorhynchusmykiss) in refrigerator storage. Lyophilized cultured of S. iniae (GQ850377) and L. garvieae (Ir-170A856bp) were obtained from Department of Aquatic Health and Diseases، Faculty of Veterinary Medicine، University of Tehran، Tehran، Iran، and were used in this study. After determination of incubation dose of two bacteria (1. 4×108 and 9. 2×107 CFU/ ml) and preparation of nisin solution، incubation of bacterial was done in fish fillets. The results revealed that different concentrations of nisin were statistically different in reduction of bacteria comparing with control group (P<0. 05). The highest inhibitory effect was observed in 0. 75 µg/ ml 65. 77% on L. garvieae and 60. 88 % on S. iniae. Thatresults showed that nisin، as a preservative، can be effective in control of food-borne bacteria in foodstuff.

Streptococcus iniae is an emerging zoonotic pathogen that represents a threat to the aquaculture industry worldwide and poses a risk to humans’ health. The aim this study, was to evaluate the effect of cumin (Cuminum cyminum) essential oil and nisin on the growth of S. iniae. For this purpose, the fillets of rainbow trout (Oncorhynchus mykiss) were inoculated with 103 of S. iniae and afterwards were treated with the different concentrations of cumin essential oil (0, 0.005, 0.135 and 0.405%) as well as nisin (0, 0.25 and 0.75 μg/ml). The samples were stored at 4 and 10 ºC for 15 days. Results revealed that in the samples stored at 4 °C the solo application of each of nisin and cumin essential oil could inhibit the growth of S. iniae until day 9; meanwhile, in combining form the inhibition of bacterial growth was occurred for 3 days. In the samples stored at 10 ºC, nisin and cumin essential oil hindered the bacterial growth for 3 and 6 days, respectively. Moreover, combination of the two materials inhibited the bacterial growth until day 6. The highest synergistic effect was observed in 0.405% of cumin essential oil and 0.75 μg/ml of nisin at 4 ºC. However, at 10 ºC, 0.135 and 0.405% of cumin essential oil together with 0.75 μg/ml of nisin had the highest synergistic effect. As a significant (P<0.05) difference was observed between the treatment and control groups, it could be concluded that cumin essential oil and nisin could efficiently inhibit the growth of S. iniae.

In this study, the inhibitory effects of bacteriocins of lactobacilli which were isolated from Iranian traditional dairy products was determined against known gram positive, gram negative and yeast by well diffusion technique. Among 8 isolates with higher capability of bacteriocin production, 2 isolates were selected for further investigations. The bacteriocins were purified by iso-propanol and ammonium sulfate precipitation following by dialysis and chromatography technique. The molecular weight of bacteriocins was determined as 45 to 66/2 KDa. by SDS-page electrophoresis. According to the results, the produced bacteriocins had more inhibition effect on Micrococcus luteus PTCC1169, Staphylococcus epidermidis PTCC1435 as well as Bacillus cereus PTCC1247 and with lesser degree of extent on Listeria monocytogenes PTCC 1301. Results also revealed that, Micrococcus luteus was the most sensitive bacterium among indicator bacteria, while Candid albicans PTCC 5027 identified as the most resistance organism. This research showed that, bacteriocins produced by lactobacilli isolated from traditional dairy products have high potency to be used against microbial pathogens and could be applied as biopreservative in food products.

In the present study, the anti-listeria activity of onion (Allium cepa L.) essential oil (EO), nisin as well as their combination at various pH values (4.8, 5.8 and 6.8) and different NaCl concentrations (0, 0.5, 2.5 and 4.5%) was investigated against Listeria monocytogenes by microtiter plates at 30°C. Minimum inhibitory concentrations (MICs) were assessed for the nisin, onion EO as well as their combination. Subsequently, fractional inhibitory concentration (FIC) was evaluated under different pH and NaCl concentrations. Both nisin and EQ showed significant antimicrobial effects against L.monocytogenes. Moreover, the nisin and onion EO exhibited MICs of 12.5 IU mL-1 and 125 μg mL-1, respectively. FICs of the nisin and onion EO alone and in combined form, along with various combinations of pH and NaCl concentration, showed clearly anti-listeria effect as synergistic, additional or indifference. Regardless of NaCl concentrations, the anti-listeria activity of both agents was strongly influenced by pH. Moreover, regardless of pH value, the growth of the bacterium was also affected by increasing of NaCl concentrations. It was concluded that, pH value of 4.8 and NaCl concentration of 4.5% had significant anti-listeria effect. In addition, it was found that, the effect of NaCl concentrations for each of the combination forms of treatments at various pH was different.Therefore, there are necessity to design and apply a comprehensive predictive model.

There is increasing demand for use of natural preservatives such as bacteriocins to control foodborne pathogens in seafoods. This study was performed to evaluate the antimicrobial effects of Nisin on Staphylococcus aureus in light and heavy salted silver carp fillets (4 and 8% Nacl). Effect of different concentrations of Nisin (0, 0.15, 0.25, 0.75, 1.5 µg/ml) on behavior of S.aureus at unfavourable refrigeration storage temperature (10oC) was determined by evaluation of the bacterial growth in salted fish fillets. The results showed that used concentrations of Nisin had inhibitory effect on the growth of S.aureus in light and heavy salted fish fillets compared to the control (p<0.05). This study showed inhibitory effect of Nisin on the growth of S.aureus. Therefore it can be considered as a natural preservative in light and heavy salted fish.

Combination of antimicrobial agents can enhance the inhibition of foodborne pathogens and food spoilage organisms. The aim of the study was to evaluate the antimicrobial activity of Stachys lavandulifolia Vahl. essential oil in combination with nisin or glycine, in order to find synergism, indifferent or antagonism interactions. The essential oil of plant was obtained by a clevenger-type apparatus. In order to determine chemical composition, the volatile oil was injected to a GC followed by GC/MS. Antimicrobial properties of the oil, nisin and glycine were determined by a microbroth dilution method, separately. Antimicrobial interactions were carried out using a Checkerboard titration and Fractional Inhibitory Concentration Indices (FICI) were calculated, consequently. Linalool was the most abundant constituent among the oil constituents. The gram negative bacteria and the yeasts were the most resistant and sensitive against glycine and essential oil, respectively. Listeria monocytogenes was the most sensitive and Candida albicans and gram negatives were the most resistant against nisin. Nisin and oil combination resulted in a synergism effect, but the glycine and oil combination led to antagonism, indifferent or additive effects. Antimicrobial interaction of essential oil of Stachys with nisin or glycine resulted in decrease of minimum inhibitory concentrations that was more important for gram negative bacteria and yeasts inhibition. However, minimizing the minimum inhibitory concentrations lonely isn’t equal to a synergism effect and may conclude additive, indifferent or antagonism effects.