The Effects of High Pressure Processing on Peanut Sauce Inoculated with Salmonella

Recent Salmonella outbreaks have prompted the need for new processing options for peanut products. Traditional heating kill-steps have shown to be ineffective in lipid-rich matrices such as peanut products. High pressure processing is one such option for peanut sauce because it has a high water activity, which has proved to be a large contributing factor in microbial lethality due to high pressure processing. Four different formulations of peanut sauce were inoculated with a five strain Salmonella cocktail and high pressure processed. Results indicate that increasing pressure or increasing hold time increases log10 reductions. The Weibull model was fitted to each kill curve, with b and n values significantly optimized for each curve (p-value < 0.05). Most curves had an n parameter value less than 1, indicating that the population had a dramatic initial reduction, but tailed off as time increased, leaving a small resistant population. ANOVA analysis of the b and n parameters show that there are more significant differences between b parameters than n parameters, meaning that most treatments showed similar tailing effect, but differed on the shape of the curve. Comparisons between peanut sauce formulations at the same pressure treatments indicate that increasing amount of organic peanut butter within the sauce formulation decreases log10 reductions. This could be due to a protective effect from the lipids in the peanut butter, or it may be due to other factors such as nutrient availability or water activity. Sauces pressurized at lower temperatures had decreased log10 reductions, indicating that cooler temperatures offered some protective effect. Log10 reductions exceeded 5 logs, indicating that high pressure processing may be a suitable option as a kill-step for Salmonella in industrial processing of peanut sauces. Future research should include high pressure processing on other peanut products with high water activities such as sauces and syrups as well as research to determine the effects of water activity and lipid composition with a food matrix such as peanut sauces.

Growth potential of Salmonella spp. and Listeria monocytogenes in nine types of ready-to-eat vegetables stored at variable temperature conditions during shelf-life

Growth potential (delta) is defined as the difference between the population of a microorganism at the end of shelf-life of specific food and its initial population. The determination of 6 of Salmonella and Listeria monocytogenes in RTE vegetables can be very useful to determine likely threats to food safety. However, little is known on the behavior of these microorganisms in several RTE vegetables. Therefore, the aim of this study was to determine the delta of both pathogens in nine different types of RTE vegetables (escarole, collard green, spinach, watercress, arugula, grated carrot, green salad, and mix for yakisoba) stored at refrigeration (7 degrees C) and abuse temperature (15 degrees C). The population of aerobic microorganisms and lactic acid bacteria, including those showing antimicrobial activity has been also determined. Results indicated that L monocytogenes was able to grow (delta >= 0.5 log(10)) in more storage conditions and vegetables than Salmonella. Both microorganisms were inhibited in carrots, although a more pronounced effect has been observed against L monocytogenes. The highest 5 values were obtained when the RTE vegetables were stored 15 degrees C/6 days in collard greens (delta=3.3) and arugula (delta=3.2) (L monocytogenes) and arugula (delta=4.1) and escarole (delta=2.8) (Salmonella). In most vegetables and storage conditions studied, the counts of total aerobic microorganisms raised significantly independent of the temperature of storage (p<0.05). Counts of lactic acid bacteria were higher in vegetables partially or fully stored at abuse temperature with recovery of isolates showing antimicrobial activity. In conclusion, the results of this study show that Salmonella and L monocytogenes may grow and reach high populations in RTE vegetables depending on storage conditions and the definition of effective intervention strategies are needed to control their growth in these products. (C) 2012 Elsevier B.V. All rights reserved.

3-Hydroxypropionic Acid as an Antibacterial Agent from Endophytic Fungi Diaporthe phaseolorum

Endophytic fungi are considered a rich source of active compounds resulting from their secondary metabolism. Fungi from marine environment grow in a habitat with unique conditions that can contribute to the activation of metabolic pathways of synthesis of different unknown molecules. The production of these compounds may support the adaptation and survival of the fungi in the marine ecosystem. Mangroves are ecosystems situated between land and sea. They are frequently found in tropical and subtropical areas and enclose approximately 18.1 million hectares of the planet. The great biodiversity found in these ecosystems shows the importance of researching them, including studies regarding new compounds derived from the endophytic fungi that inhabit these ecosystems. 3-hydroxypropionic acid (3-HPA) has been isolated from the mangrove endophytic fungus Diaporthe phaseolorum, which was obtained from branches of Laguncularia racemosa. The structure of this compound was elucidated by spectroscopic methods, mainly 1D and 2D NMR. In bioassays, 3-HPA showed antimicrobial activities against both Staphylococcus aureus and Salmonella typhi. The structure of this antibiotic was modified by the chemical reaction of Fischer-Speier esterification to evaluate the biologic activity of its chemical analog. The esterified product, 3-hydroxypropanoic ethyl ester, did not exhibit antibiotic activity, suggesting that the free carboxylic acid group is important to the pharmacological activity. The antibiotic-producing strain was identified with internal transcribed spacer sequence data. To the best of our knowledge, this is the first report of antibacterial activity by 3-HPA against the growth of medically important pathogens.

Lactobacillus sakei 2a and its Concentrated Acid Extract on Inhibition of Food-Borne Salmonella strains

Lactic acid bacteria are used in food production to provide desirable organoleptic characteristics, and can also act as biopreservatives, controlling the growth of undesirable microorganisms. In this study, we examined the antimicrobial action of Lactobacillus sakei 2a and its concentrated acid extract against food-borne Salmonella spp. The extract was obtained by acid extraction from culture broth of L. sakei 2a and was designated extract 2a. We determined that extract 2a had significant activity (approximately 500 AU ml(-1)). We used different antimicrobial substances alone or in combination with extract 2a to evaluate the inhibitory activity of the various treatments on a pool of five Salmonella strains. The pathogen Listeria monocytogenes Scott A Cm-r Em(r) was used as an indicator strain of inhibitory activity. In summary, all antimicrobials substances that were tested showed an inhibitory effect against the growth of Salmonella, andthis action was enhanced in the presence of extract 2a. Moreover, among the treatments applied, the combination of extract 2a and 0.1% lactic acid exhibited the most potent inhibitory effect towards the pool of Salmonella strains. Our findings indicate that L. sakei 2a and extract 2a, especially in combination with other antimicrobials, present potential technological application in the control of salmonellae in foods.

Current perspectives in avian salmonellosis: Vaccines and immune mechanisms of protection

Salmonellosis is one of the most prevalent foodborne diseases worldwide. Food animals have been identified as reservoirs for nontyphoid Salmonella infections. in poultry, host-specific Salmonella infections cause fowl typhoid and pullorum diseases that produce economic losses in different parts of the world. Several measures have been used to prevent and control Salmonella infections in poultry, and vaccination is the most practical measure because it avoids contamination of poultry products and by-products and prevents disease in humans. Salmonella vaccines can decrease public health risk by reducing colonization and organ invasion, including invasion of reproductive tissues, and by diminishing fecal shedding and environmental contamination. We review available information on the host-specific and non-host-specific Salmonella serotypes found in poultry and the improved understanding of the pathogenesis of and immune responses to infection. We also include some approaches based on updated publications regarding killed and live attenuated vaccines and their immune mechanisms of protection.

Heat stress impairs performance and induces intestinal inflammation in broiler chickens infected with Salmonella Enteritidis

Stressful situations reduce the welfare, production indices and immune status of chickens. Salmonella spp. are a major zoonotic pathogens that annually cause over 1 billion infections worldwide. We therefore designed the current experiment to analyse the effects of 31 +/- 1 degrees C heat stress (HS) (from 35 to 41 days) on performance parameters, Salmonella invasion and small intestine integrity in broiler chickens infected with Salmonella Enteritidis. We observed that HS decreased body weight gain and feed intake. However, feed conversion was only increased when HS was combined with Salmonella Enteritidis infection. In addition, we observed an increase in serum corticosterone levels in all of the birds that were subjected to HS, showing a hypothalamus-pituitary-adrenal axis activation. Furthermore, mild acute multifocal lymphoplasmacytic enteritis, characterized by foci of heterophil infiltration in the duodenum, jejunum and ileum, was observed in the HS group. In contrast, similar but more evident enteritis was noted in the heat-stressed and Salmonella-infected group. In this group, moderate enteritis was observed in all parts of the small intestine. Lastly, we observed an increase in Salmonella counts in the spleens of the stressed and Salmonella-infected chickens. The combination of HS and Salmonella Enteritidis infection may therefore disrupt the intestinal barrier, which would allow pathogenic bacteria to migrate through the intestinal mucosa to the spleen and generate an inflammatory infiltrate in the gut, decreasing performance parameters.

Molecular and serological characterization of Leptospira interrogans serovar Canicola isolated from dogs, swine, and bovine in Brazil

The identification of Leptospira clinical isolates through genotyping and serotyping, besides the recognition of its reservoirs, are important tools for understanding the epidemiology of leptospirosis, and they are also keys for identifying new species and serovars. Fourteen clinical isolates from animals were characterized by means of single enzyme amplified length polymorphism, variable number of tandem repeat analysis, pulsed field gel electrophoresis, and serotyping. All isolates were identified as Leptospira interrogans, serovar Canicola. Infections by this serovar occur in urban regions, where dogs represent the main maintenance hosts, whereas bovine and swine may act as reservoirs of serovar Canicola in rural areas. Both urban and rural aspects of leptospirosis, and the role of domestic animals as maintenance hosts, cannot be neglected in developing and developed countries.

Genotoxicity assessment of water soluble fractions of biodiesel and its diesel blends using the Salmonella assay and the in vitro MicroFlow (R) kit (Litron) assay

The designation of biodiesel as an environmental-friendly alternative to diesel oil has improved its commercialization and use. However, most biodiesel environmental safety studies refer to air pollution and so far there have been very few literature data about its impacts upon other biotic systems, e.g. water, and exposed organisms. Spill simulations in water were carried out with neat diesel and biodiesel and their blends aiming at assessing their genotoxic potentials should there be contaminations of water systems. The water soluble fractions (WSF) from the spill simulations were submitted to solid phase extraction with C-18 cartridge and the extracts obtained were evaluated carrying out genotoxic and mutagenic bioassays [the Salmonella assay and the in vitro MicroFlow (R) kit (Litron) assay]. Mutagenic and genotoxic effects were observed, respectively, in the Salmonella/microsome preincubation assay and the in vitro MN test carried out with the biodiesel WSF. This interesting result may be related to the presence of pollutants in biodiesel derived from the raw material source used in its production chain. The data showed that care while using biodiesel should be taken to avoid harmful effects on living organisms in cases of water pollution. (C) 2011 Elsevier Ltd. All rights reserved.

Leptospira interrogans serovar Copenhageni harbors two lexA genes involved in SOS response

Bacteria activate a regulatory network in response to the challenges imposed by DNA damage to genetic material, known as the SOS response. This system is regulated by the RecA recombinase and by the transcriptional repressor lexA. Leptospira interrogans is a pathogen capable of surviving in the environment for weeks, being exposed to a great variety of stress agents and yet retaining its ability to infect the host. This study aims to investigate the behavior of L. interrogans serovar Copenhageni after the stress induced by DNA damage. We show that L. interrogans serovar Copenhageni genome contains two genes encoding putative LexA proteins (lexA1 and lexA2) one of them being potentially acquired by lateral gene transfer. Both genes are induced after DNA damage, but the steady state levels of both LexA proteins drop, probably due to auto-proteolytic activity triggered in this condition. In addition, seven other genes were up-regulated following UV-C irradiation, recA, recN, dinP, and four genes encoding hypothetical proteins. This set of genes is potentially regulated by LexA1, as it showed binding to their promoter regions. All these regions contain degenerated sequences in relation to the previously described SOS box, TTTGN 5CAAA. On the other hand, LexA2 was able to bind to the palindrome TTGTAN 10TACAA, found in its own promoter region, but not in the others. Therefore, the L. interrogans serovar Copenhageni SOS regulon may be even more complex, as a result of LexA1 and LexA2 binding to divergent motifs. New possibilities for DNA damage response in Leptospira are expected, with potential influence in other biological responses such as virulence

Epidemiología de salmonella en Gran Canaria

[ES] Se recoge información sobre el origen, distribución y sensibilidad a los antibiotícos de las salmonelas aisladas en Gran Canaria en los últimos años. La frecuencia de serotipos aislados a partir de humanos y animales así como del medio ambiente ha sido estudiada

Bacterias patógenas humanas en aguas naturales : estudio sobre la presencia de "Salmonella spp" en diferentes zonas de interés público en el litoral canario

[ES]En el litoral se produce la influencia de numerosos factores ajenos al medio marino procedentes del entorno terrestre. Así, la presencia de patógenos humanos en el agua de mar se investiga desde hace muchas décadas, siguiendo la Directiva 76/160/CEE, de calidad de aguas de baño. La presencia de Salmonella en relación con otros microorganismos fecales es un importantísimo factor ecológico y sanitario a considerar. Durante años hemos aislado numerosas serovariedades de Salmonella en zonas marinas contaminadas por aguas residuales.

Use of an indirect enzyme-linked immunosorbent assay for detection of antibodies in sheep naturally infected with Salmonella Abortusovis

An indirect enzyme-linked immunosorbent assay (ELISA) was modified and validated to detect antibodies against Salmonella Abortusovis in naturally infected sheep. The ELISA was validated with 44 positive and 45 negative control serum samples. Compared with the immunoblot, the sensitivity and specificity of the assay were 98% and 100%, respectively. To follow antibody levels over time, samples from 12 infected ewes were collected at 1, 3, and 10 months after abortion. All animals showed antibody levels above the cutoff value throughout the observation period. One and 3 months after abortion, high antibody levels could be detected in all but one animal, whereas after 10 months, 9 animals had markedly lower but still positive antibody levels. The test characteristics and evidence for the persistence of detectable antibody levels in all infected animals for up to 10 months indicates that the ELISA can be used for herd surveillance testing.