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Microscopic view (1,0003) of massive gelatinous aggregates of early exponential phase cells of A. hydrophila (simple staining with crystal violet) treated with SAPP (0.5%), pH 6, for 0.5 h at 258C.
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Aeromonas hydrophila is considered to be an emergent food-related bacterium. Phosphates are used as additives, mainly in meat products, to improve the quality of these foods. The antibacterial properties of phosphates are also well known. In this work, two A. hydrophila strains in early exponential phase were used: (A) A. hydrophila ATCC 7965 and (...
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Context 1
... spectrophotometrically determined (260 nm) bacteriolytic effect of SAPP was conn rmed microscopically. Figure 5 shows a control preparation and Figure 6 shows the massive gelatinous aggregates when A. hydrophila cells were treated with 0.5% SAPP. These aggregates were identii ed by enzymes (DNase, RNase, and proteinase K). ...
Context 2
... on the dissolution of the gelatinous aggregates was as follows: DNase 1 RNase 1 proteinase K . DNase . proteinase K . RNase. Similar results were obtained by other authors on gram-positive bacteria (17). When the cells were treated with SAPP enzyme(s), fewer gelatinous aggregates were observed (Fig. 7) as compared to the cells treated with SAPP (Fig. 6). The presence of gelatinous aggregates depended on the type of enzyme(s) used. On the other hand, the phosphates are inhibitors of nucleases (17). Therefore, it could be inferred that the gelatinous aggregates accumulated that remained undissolved after the treatment with nucleases are the product of the inhibiting effect of phosphates ...
Citations
... The mixture in 96-well plate was cultured at 30 • C or 37 • C for 16 h, and then the absorbance of each well at 600 nm was detected via microplate reader of multi-wavelength (Thermo Fisher Scientific, BioTek, USA). As previously reported, MIC was defined as the lowest peptide concentration at which no bacteria growth was observed [43][44][45][46]. As for determination of MBC, 100 μl of mixture with TroNKL-27 whose concentrations were equal to or higher than the MIC values was applied on solid plates. ...
NK-lysin, a homologue of granulysin among human, is predominantly found in natural killer cells and cytotoxic T-lymphocytes, which plays a pivotal part in innate immune responses against diverse pathogenic bacteria. Nonetheless, in teleosts, the research on antimicrobial activity and mechanisms of NK-lysin are seldom reported. In this study, we determined the antimicrobial activity of the truncated peptide TroNKL-27 that derived from golden pompano (Trachinotus ovatus) NK-lysin, and investigated its antimicrobial mechanisms. The results showed that TroNKL-27 had considerable antimicrobial potency against both Gram-positive (Staphylococcus aureus, Streptococcus agalactiae) and Gram-negative bacteria (Vibrio harveyi, V. alginolyticus, Escherichia coli, Edwardsiella tarda). Cytoplasmic membrane depolarization and propidium iodide (PI) uptake assay manifested that TroNKL-27 could induce the bacterial membrane depolarization and change its membrane permeability, respectively. In the light of scanning electron microscopy (SEM) observation, TroNKL-27 was capable of altering morphological structures of bacteria and leading to leakage of cellular contents. Moreover, the results of gel retardation assay indicated TroNKL-27 had the ability to induce the degradation of bacterial genomic DNA. As regards in vivo assay, TroNKL-27 could reduce the replication of V. harveyi in tissues of golden pompano, protect the tissue from pathological changes. Moreover, TroNKL-27 in vivo could significantly increase the expression of the immune genes (such as IL1β, TNFα, IFN-γ, C3 and Mx) in presence or absence of V. harveyi infection. All of these results suggest that TroNKL-27 is a novel antimicrobial peptide possessing antibacterial and immunoregulatory function in vivo and in vitro, and the observed effects of TroNKL-27 will lay a solid foundation for the development of new antimicrobial agents used in aquaculture.
... The polyphosphate NaCl mixture inhibited bacterial growth in ground pork during refrigerated storage. According to Velazquez et al. [169] the growth of A. hydrophila was completely inhibited by concentrations between 0.5 and 3.0% of four phosphates (tetrasodium pyrophosphate, sodium acid pyrophosphate, trisodium phosphate and sodium tripolyphosphate) in modified completely defined synthetic medium (mCDS) and cooked ground meat medium. A stronger inhibitory impact (bactericidal and bacteriolytic effects) was produced by sodium acid pyrophosphate (0.5%) [15]. ...
... Aeromonas hydrophila is a widespread representative species of Aeromonas found in water, water habitants, domestic animals and foods (Rashid et al., 1992;Dascalov, 2006;Djuikom et al., 2008). It is mainly considered to be an emergent food-related bacterium (Velazquez et al,. 2001;Motta et al.,. 2007). Food and water-borne illnesses are the major important problems in the world, because of improperly treated water and unhygienic animal foodstuffs. The mesophilic Aeromonas has been likely to cause many human infections (Condon et al.,. 1991). The organism has been isolated from a range of foods in almost every coun ...
This study was carried out in lamb and chicken meat retail outlets located in Coimbatore city, Tamilnadu, India during September 2005 to February 2006. Lamb and chicken meat and the accessories like chopping boards, knifes, balance trays, washing water and hands of the butchers were examined. A total of 63 A. hydrophila strains were isolated from lamb and chicken meat retail outlets. The highest incidence was found in butchers hand and washing water. Survival study was carried out using selected strains of A. hydrophila (SLM-4) on lamb, chicken meat and egg samples at various temperatures (30, 10 and 4 o C). The temperature at 30 o C stimulates the survivability of A. hydrophila in all the samples. However, the organism survives even at low temperature (4 o C). Similarly, the bacterium survived significantly in the stainless steel, wood and iron pieces showing the adhering ability of the organism. Traditional cooking process (100 o C) proved complete elimination of A. hydrophila. In the study of antibiotic sensitivity, all the strains isolated from lamb and chicken meat outlets were resistant to ampicillin and bacitracin. The resistance showed < 20% by using the antibiotics, chloramphenicol, gentamycin, nalidixic acid, streptomycin and sulphamethoxazole.
... In ground pork, the polyphosphate-NaCl combination limited growth of the bacterium during refrigerated storage. Velazquez, Escudero, and de Guzman (2001) assessed the antibacterial effects of four phosphates (tetrasodium pyrophosphate, sodium acid pyrophosphate, trisodium phosphate and sodium tripolyphosphate) on growth of A. hydrophila; the growth of A. hydrophila was totally inhibited by concentrations between 0.5% and 3.0% in modified complete defined synthetic medium (mCDS) and cooked ground meat medium (CM). Sodium acid pyrophosphate (0.5%) had greater inhibitory effect (bactericidal and bacteriolytic effects). ...
Aeromonas hydrophila is a widespread representative of Aeromonas found in water, water habitants, domestic animals and foods (fish, shellfish, poultry, and raw meat). The microorganism has the potential to be a foodborne pathogen, especially strains from hybridization group (HG1), associated with clinical cases of illness. The pathogen produces different virulence factors including exotoxins, cytotoxins and others. As a psychrotroph, A. hydrophila grow in foods during refrigeration. The disease spectrum associated with this microorganism includes gastroenteritis, septicemia, traumatic and aquatic wound infections, and infections after medical leech therapy. Multiple resistance of the bacterium to many antimicrobials is a fact of high significance. The potential of A. hydrophila to become a foodborne pathogen is a controversial issue. Many approaches are effective for control of the presence of A. hydrophila in food for human consumption.
... There are additional reports indicating that antimicrobial agents that are highly ef cacious in broth systems often lose activity in the more complex environments of foods (22). It was recently shown that TSP was far less active in a cooked ground meat medium than it was in commercial broth systems (45). The presence of proteins (i.e., bovine serum albumin) and complex organic molecules has been shown to impair the ef cacy of antimicrobial agents (37). ...
A two-step approach for enhancing the efficacy of trisodium phosphate (TSP) was evaluated using meat spoilage and pathogenic bacteria in flow cell biofilms and adipose tissue model systems. The process was based on the plasmolysis of attached bacteria (biofilms) with a hyperosmotic solution (1.5 M NaCl) and the subsequent deplasmolysis of cells with a low-osmotic-strength solution containing different concentrations of TSP (0.1, 0.25, 0.5, 0.625, and 1.0 % [wt/vol]). Escherichia coli, Salmonella Enteritidis, Pseudomonas sp., Listeria monocytogenes, and Brochothrix thermosphacta strains were cultivated for 24 h as pure culture biofilms in glass flow cells with complex media and were then treated with either 0.1, 0.25, 0.5, 0.625, and 1.0% TSP, or the same TSP concentrations delivered in conjunction with plasmolysis-deplasmolysis (PDP). Confocal scanning laser microscopy, a commercial fluorescent viability probe, and image analysis were then used to quantify the relative abundances of living and dead cells remaining after the different treatment regimes. With the exception of L. monocytogenes (which was resistant to TSP concentrations of up to 5%), the PDP process increased the sensitivity of the test strains to TSP. However, when similar experiments were conducted with pork adipose tissue, it became evident that higher TSP concentrations were necessary to produce significant decreases in the number of viable cells and that the PDP process generally failed to enhance TSP efficacy. An exception was L. monocytogenes, which exhibited an increase in sensitivity to TSP when inoculated tissue was pretreated with 1.5 M NaCl. It is thought that factors contributing to the failure of the PDP process to enhance the activity of TSP in meat systems involves the mode of TSP antimicrobial activity, alkaline pH stress, and the chemically complex, buffered nature of meats. It remains to be determined whether the PDP process is suitable for use with other food grade antimicrobial agents or can be used in nonfood biofilm control applications.
... are widely distributed in the aquatic environment and have been isolated from various seafoods and dairy products during refrigerated storage (43). Most species are psychrotrophs and reported as emerging foodborne pathogens associated with septicemia and gastroenteritis in humans (42). Although A. hydrophila has not been frequently reported as a histamine former, it was isolated from both fresh and spoiled sh at 48C in this study. ...
Bacterial growth and histamine formation in Pacific mackerel during storage at 0, 4, 15, and 25 degrees C were monitored. To identify bacterial species contributing to histamine formation, several groups of bacteria were isolated by using selective media under temperatures corresponding to the various storage conditions. Initially, low counts of bacteria were found in the gill, skin, and intestine of fresh fish, and only weak histamine formers were found in the gill. Histamine was found in the muscle when fish were stored above 4 degrees C, and aerobic plate counts reached 10(6) CFU/g. When fish became unsuitable for human consumption by abusive storage, toxicological levels of histamine were always found. The highest level of histamine formed was 283 mg/100 g in 2 days. The optimum temperature for supporting growth of prolific histamine formers was 25 degrees C. The most prolific and prevalent histamine former was Morganella morganii, followed by Proteus vulgaris, both of which were isolated on violet red bile glucose (VRBG) agar. At 15 degrees C, a significant level of histamine was still produced in fish muscle, although prolific histamine formers were less frequently detected than at 25 degrees C. The isolates on thiosulfate citrate bile salts sucrose (TCBS) agar were weak histamine formers and identified as Vibrio parahaemolyticus and Vibrio alginolyticus. At 4 degrees C, less than 57.4 mg/100 g of histamine was found in fish stored for 14 days. Most isolates were natural bacterial flora in the marine environment and identified as weak histamine formers. At 0 degrees C, neither histamine former nor histamine production was detected up to 14 days of storage.
Aeromonas hydrophila is a freshwater, facultatively anaerobic, chemo-organoheterotrophic bacterium that distressed fishes with gastroenteritis, septicemia and causes a disease known as Motile Aeromonas Septicemia (MAS), which affects the aquatic environment. Haemolysin, aerolysin, cytosine, gelatinase, enterotoxin and antimicrobial peptides have been identified as virulence factors in A. hydrophila. Medicinal herbs/plants and their uses are the instant, easily available, cost-effective, efficient and eco-friendly approach for socio-economic, sustainable development of modern aquaculture practice. Phytotherapy either through a dip or by incorporation into the diets is an alternative approach to synthetic pharmaceuticals to diminish the pathogenicity of aquatic environmental pathogens. Due to the presence of remarkable phytoconstituents like flavonoids, alkaloids, pigments, terpenoids, steroids and essential oils, the
medicinal plant exhibits anti-microbial, appetite-stimulating, anti-stress, growth-promoting and immunostimulatory activities. Aqua-industry preferred phytotherapy-based techniques/ compounds to develop resistance against a variety of aquatic pathogens in culturable fishes because they are inexpensive and environment-friendly. As a result, this review elaborates on the diverse applications of phytotherapy as a promising tool for disease management in aquaculture and a major step toward organic aquaculture.
The aim of the chapter was to explain the importance of emulsifying salts during processed cheese production. Firstly, the principles of emulsifying salts action in the model system or processed cheese were described. In particular, the phase of ion exchange and liberating of caseins and their action in the process of water hydration and fat emulsification were characterized. Hence, the formation of new protein matrix during so called “creaming phase” was explained. The chapter was focused especially on phosphate- and citrate-based emulsifying salts. Moreover, the role of solely used phosphates and citrate (sodium salts) was characterized. Additionally, the more complicated systems of binary and ternary mixtures of phosphates and/or citrates were also described. Legislative aspects of emulsifying salts used were taken into account, too. At the end of the chapter, the possibility of traditional emulsifying salts substitution was described and four possible approaches were presented.
Aeromonas hydrophila is an opportunistic pathogen that is responsible for a variety of infectious diseases both in human and animals, particularly aquatic animals. Moreover, the pathogen has become a foodborne pathogen by transmitting from seafood to human. The abuse of antibiotics in aquaculture results in the emergence of antibiotic resistance and treatment failure. Therefore, novel approaches are urgently needed for managing resistant A. hydrophila associated infections. Aerolysin, an essential virulence factor of pathogenic A. hydrophila strain, has been identified as target developing novel drugs against pathogenesis of A. hydrophila. In the present study, genistein, without anti-A. hydrophila activity, was identified that could decrease the production of aerolysin and biofilm formation at a dose-dependent manner. Transcription of aerolysin encoding gene aerA and quorum sensing related genes ahyI and ahyR was significantly down-regulated when co-cultured with genistein. Cell viability studies demonstrated that genistein could significantly improve aerolysin mediated A549 cell injury. Furthermore, genistein could provide a remarkable protection to channel catfish infected with A. hydrophila. These findings indicate that targeting quorum sensing and virulence can be a useful approach developing drugs against A. hydrophila infections in aquaculture. Moreover, genistein can be chosen as a promising candidate in developing drugs against A. hydrophila.
In the food industry, phosphates, polyphosphates and their salts are used, for example, as emulsifying agents in the production of processed cheese. The inhibitory effects of three commercially available phosphates and polyphosphates differing in their chain length (690, S9 and HBS) were tested on a set of 15 gram-positive or gram-negative CCM (Czech Collection of Microorganisms) strains and on 12 bacterial strains isolated from processed cheeses. Five different concentrations of each phosphate were chosen (0.1, 0.2, 0.3, 0.4 and 0.5% w/v) in order to observe the inhibitory effects of the phosphate salts on the growth of the microorganisms tested. Sensitivity of the individual bacterial strains to phosphates was observed of a liquid cultivation medium which was supplemented with applied salts. Subsequently, the growth in cells was determined by measuring optical density at a wavelength of 600 nm. According to the results, 690 and S9 phosphates, containing mainly orthophosphates, diphosphates (pyrophosphates) and short-chain polyphosphates, do not have a significant inhibitory effect on the growth of the tested bacteria. Significant inhibitory effects were observed only in HBS salt (a mixture of long-chain polyphosphates), which showed antibacterial effects on all gram-positive bacteria tested (both the CCM strains and those isolated from processed cheeses). The antibacterial effect of phosphates on gram-positive microorganisms is growing with the increasing length of the polyphosphate chain. This study has not proved a significant effect of the phosphates tested on the growth of gram-negative bacteria used.
