Survival of Vibrio parahaemolyticus in Fish Homogenate During Storage at Low Temperatures

Fish homogenate inoculated with Japanese strains of Vibrio parahaemolyticus were either stored at 0.6 C or frozen and stored at -18 and -34 C. Greater survival of the organisms was obtained at 0.6 C than at the lower temperatures.     

Interacting Effects of pH, Temperature, and Salt Concentration on Growth and Survival of Vibrio parahaemolyticus

Thermal resistance and minimal pH and temperature conditions for growth of Vibrio parahaemolyticus in artificial media containing 3 and 7% sodium chloride were studied. Growth was observed at pH 4.8 and at 5 C.     

Acanthamoeba castellanii Promotes the Survival of Vibrio parahaemolyticus

Vibrio parahaemolyticus is a food-borne pathogen that naturally inhabits both marine and estuarine environments. Free-living protozoa exist in similar aquatic environments and function to control bacterial numbers by grazing on free-living bacteria. Protozoa also play an important role in the survival and spread of some pathogenic species of bacteria. We investigated the interaction between the protozoan Acanthamoeba castellanii and the bacterium Vibrio parahaemolyticus. We found that Acanthamoeba castellanii does not prey on Vibrio parahaemolyticus but instead secretes a factor that promotes the survival of Vibrio parahaemolyticus in coculture. These studies suggest that protozoa may provide a survival advantage to an extracellular pathogen in the environment.     

Antigenic Relationships Among Strains of Vibrio parahaemolyticus

The antigenic relationships of 79 strains of Vibrio parahaemolyticus representing 46 assigned K-types were studied by tube agglutination. Homologous titers of 46 anti-K sera ranged from 80 to 2,560. All but three sera exhibited from one to six heterologous reactions, the majority of which gave titers of 相似文献   

Survival of Vibrio parahaemolyticus in cold smoked fish

Fresh samples of mullet (Mugil cephalus) and oil sardines (Sardinella longiceps) obtained from a fish market were subjected to cold smoking. Some of the samples harboured low levels of Vibrio parahaemolyticus. After cold smoking, however, many samples showed relatively high levels of V. parahaemolyticus suggesting that a small population of naturally occuring organisms could multiply to significant levels during the process of cold smoking or during subsequent storage at room temperature. Nevertheless, smoke components were observed to exert an inhibitory effect on V. parahaemolyticus in broth. Salt concentration 1% appeared to increase the sensitivity of V. parahaemolyticus to smoke components.     

Survival of Vibrio parahaemolyticus in Cooked Seafood at Refrigeration Temperatures

The growth and survival of two strains of Vibrio parahaemolyticus isolated during food-borne gastroenteritis outbreaks in Japan and surface inoculated on cooked shrimp, shrimp with sauce, or cooked crab were tested at various refrigeration temperatures during a 48-h holding period. On cooked shrimp and crab, the vibrios grew well at 18.3 C, but their numbers declined gradually at 10 C and below. At 12.8 C, vibrios remained static for the most part. Thus, it appeared that 12.8 C was the borderline temperature for growth of the organism on cooked seafood. When cocktail sauce was added to surface-inoculated shrimp at a ratio of 2:1, the vibrio die-off rate was accelerated. In the shrimp and sauce few cells remained after 48 h, but in the sauce alone die-off was complete at 6 h.     

Toxicity of Sodium and Chloride Ions to Rhizobium spp. in Broth and Peat Culture

The growth of a strain of Rhizobium trifolii and of R. meliloti was studied in broth and peat cultures to determine the relative toxicity of Na⁺ and Cl^-. The following salts were added in a range of concentrations: Na₂HPO₄ as a source of Na⁺, CaCl₂.2H₂O as a source of Cl^-, and NaCl. Disodium hydrogen orthophosphate affected the growth rate of both strains in broth culture but not in peat culture. Unexpectedly, calcium chloride was more toxic than NaCl in broth and peat culture. The toxicity of NaCl can be ascribed to the Cl^-. Rhizobium meliloti strains grew on 3·5% NaCl after adaptation during a long period. Rhizobia for soya bean and cowpea grew at 0·5% NaCl and those for clover and pea, at 1·0% NaCl.     

Survival of Vibrio parahaemolyticus in Shrimp Tissue Under Various Environmental Conditions

Vibrio parahaemolyticus culture O from Gulf Coast shrimp was inoculated into whole shrimp and shrimp homogenate to determine its survival at various temperatures and pH values. Although large decreases in viable population occurred during storage for 2 days at 10 to -18 C, survivors were present even after 8 days. No significant differences were observed in the population changes of inoculated whole shrimp as compared with shrimp homogenates. Low populations (5 x 10(2) per ml) of V. parahaemolyticus were destroyed by heating shrimp homogenates at 60, 80, and 100 C for 1 min. With larger populations (2 x 10(5) per ml), some survivors were present after heating at 60 and 80 C for 15 min. None survived 1 min at 100 C. V. parahaemolyticus was very sensitive to pH values below 6.0. Cells survived for several hours in the contents of the porcine gastrointestinal tract.     

Survival of Vibrio parahaemolyticus in Oyster Shellstock at Two Different Storage Temperatures

In oyster shellstock harvested from Maryland waters Vibrio parahaemolyticus was found to be present, to survive storage for at least 3 weeks at 4 C, and to multiply after being held for 2 to 3 days at 35 C.     

A Comparison of Measures of Boldness and Their Relationships to Survival in Young Fish

Boldness is the propensity of an animal to engage in risky behavior. Many variations of novel-object or novel-environment tests have been used to quantify the boldness of animals, although the relationship between test outcomes has rarely been investigated. Furthermore, the relationship of outcomes to any ecological aspect of fitness is generally assumed, rather than measured directly. Our study is the first to compare how the outcomes of the same test of boldness differ among observers and how different tests of boldness relate to the survival of individuals in the field. Newly-metamorphosed lemon damselfish, Pomacentrus moluccensis, were placed onto replicate patches of natural habitat. Individual behavior was quantified using four tests (composed of a total of 12 different measures of behavior): latency to enter a novel environment, activity in a novel environment, and reactions to threatening and benign novel objects. After behavior was quantified, survival was monitored for two days during which time fish were exposed to natural predators. Variation among observers was low for most of the 12 measures, except distance moved and the threat test (reaction to probe thrust), which displayed unacceptable amounts of inter-observer variation. Overall, the results of the behavioral tests suggested that novel environment and novel object tests quantified similar behaviors, yet these behavioral measures were not interchangeable. Multiple measures of behavior within the context of novel environment or object tests were the most robust way to assess boldness and these measures have a complex relationship with survivorship of young fish in the field. Body size and distance ventured from shelter were the only variables that had a direct and positive relationship with survival.     

Relationships between heat resistance and phospholipid fatty acid composition of Vibrio parahaemolyticus.

Vibrio parahaemolyticus was grown in tryptic soy broth (TSB) containing NaCl levels of 0.5, 3.0, and 7.5% (wt/vol). Cultures incubated at 21, 29, and 37 C were harvested in late exponential phases and thermal death times at 47 C (D47 c; time at 47 C required to reduce the viable population by 90%) were determined in phosphate buffer containing 0.5, 3.0, and 7.5% NaCl. At a given NaCl concentration in the growth medium, D47 c values increased with elevated incubation temperatures and with elevated levels of NaCl in the heating menstrua. Differences in thermal resistance of cells cultured at a particular temperature were greater between those grown in TSB containing 0.5 and 3.0% NaCl than between those grown in TSB containing 3.0 and 7.5% NaCl. D47c values ranged from 0.8 min (grown at 21 C in TSB with 0.5% NaCl) to 6.5 min (grown at 37 C in TSB with 7.5%, heated in 7.5% NaCl buffer). Methyl esters of major phospholipid fatty acids extracted from cells were quantitated. The ratio of saturated to unsaturated fatty acids in cells grown at a given NaCl concentration increased with elevated incubation temperature. At a particular growth temperature, however, saturated to unsaturated fatty acids ratios were lowest for cells grown in TSB containing 3.0% NaCl.     

Effect of Sodium Metabisulphite and Storage Temperature on the Survival of Vibrio cholerae on Prawns (Penaeus monodon)

Summary Sodium metabisulphite is traditionally used to control a non-microbiological spoilage symptom of prawns known as blackspot. This study was undertaken to evaluate the effect of sodium metabisulphite, at levels currently used to control blackspot, on the survival of V. cholerae on prawns during simulated commercial storage. Fresh prawns (Penaeus monodon) were divided into two batches, one of which was exposed to seawater while the other was treated with sodium metabisulphite (1%) in seawater. Two V. cholerae O1 strains were inoculated onto the prawns in separate experiments. Each of the batches were further sub-divided and stored either under chilled conditions (1.5 °C) for 14 days or under frozen conditions (−25 °C) for 49 days. At appropriate time intervals whole prawns were sampled and dilutions plated onto TCBS Cholera medium to determine numbers of V. cholerae. Experiments were performed in triplicate and uninoculated controls were included. Results indicated a significant (P < 0.05) decrease in numbers of V. cholerae on both chilled (~4 log units) and frozen (~2 log units) prawns over the storage period. A significantly (P < 0.05) greater decrease in numbers of the pathogen (up to 1.8 log units) on chilled sodium-metabisulphite-treated, as compared to chilled untreated, prawns was apparent. Sodium metabisulphite had a negligible effect on numbers of V. cholerae on frozen prawns. The use of sodium metabisulphite could be optimized and used to enhance the safety of chilled seafood in cholera-endemic countries.     

Changes in Caenorhabditis elegans exposed to Vibrio parahaemolyticus

Vibrio parahaemolyticus, which owes its origin to the marine environment, is considered as one of the most common causes of infectious diarrhea worldwide. The present study investigated the pathogenicity of V. parahaemolyticus against the model organism, Caenorhabditis elegans. Infection in the host was localized with GFP-tagged V. parahaemolyticus using confocal laser scanning microscopy. The times required for causing infection, bacterial load in intestine, chemotactic response, and alteration in pharyngeal pumping were analyzed in the host system. In addition, the regulation of innate immune-related genes, lys-7, clec- 60, and clec-87, was analyzed using real-time PCR. The role of immune-responsible pmk-1 was studied using mutant strains. The pathogenicity of environmental strain CM2 isolated from the Gulf of Mannar, India was compared with that of a reference strain obtained from ATCC. The pathogen infected animals appeared to ward off infection by upregulating candidate antimicrobial genes for a few hours after the exposure, before succumbing to the pathogen. For the first time, the pathogenicity of V. parahaemolyticus at both the physiological and molecular levels has been studied in detail using the model organism C. elegans.     

Survival of Vibrio parahaemolyticus After Chilling in Transport Media: an Explanation for Divergent Findings

Differing incidences of Vibrio parahaemolyticus reported by separate government agencies are attributable to sample handling and subsequent isolation techniques.     

DNA array with the groESL intergenic sequence to detect Vibrio parahaemolyticus and Vibrio vulnificus

The untranscribed DNA sequences of the intergenic spacer regions (ISRs) in the groESL gene of 23 Vibrio species were determined and compared. ISR sequence length (41-85 bp) was variable. Vibrio species could be divided into three groups according to the length and homology of their ISR sequences. DNA array hybridization using ISR-specific probes accurately distinguished Vibrio parahaemolyticus and Vibrio vulnificus from other species.     

EMA-LAMP方法快速检测鉴别副溶血性弧菌

建立将DNA染料EMA(ethidium bromide monoazide)结合环介导等温扩增技术(loop-mediated isother-mal amplification,LAMP)的方法(EMA-LAMP),用于检测鉴别副溶血性弧菌(Vibrio parahaemolyticus)死/活菌细胞。针对副溶血性弧菌不耐热溶血素基因tlh(thermolabile hemolysin)特异性序列的6个位点设计4条引物及2条环引物,进行检测。结果表明,浓度为8.0μg/mL或更高浓度的EMA,至少经25 min的曝光处理,能够有效抑制浓度为1×108cfu/mL的副溶血性弧菌死细胞的扩增,而对用相同浓度EMA处理的副溶血性弧菌活细胞扩增没有影响。经EMA处理,含有不同比例的副溶血弧菌死细胞和活细胞的混合液中,活菌的最小检测限为1.0×102cfu/mL。EMA-LAMP方法比EMA-PCR方法区分死活细胞中的活细胞更为有效,是一种能够快速、灵敏且更为有效鉴别副溶血性弧菌死活细胞的新方法。