Reducing Salmonella enterica serovar Enteritidis contamination in food: lytic bacteriophages in a homemade mayonnaise-like matrix / Reducción de la contaminación por Salmonella enterica serovar Enteritidis en alimentos: bacteriófagos líticos en una matriz similar a la mayonesa casera / Redução da contaminação por Salmonella enterica serovar Enteritidis em alimentos: bacteriófagos líticos em uma matriz caseira semelhante à maionese

Abstract Background: Salmonella enterica serovar Enteritidis (SE) is one of the major causes of food-borne disease worldwide, mainly associated with the consumption of poultry products, such as eggs. Several control methods have been implemented in the egg production process, but they have not effectively reduced the outbreaks. Therefore, the use of bacteriophages for the biocontrol of food-borne pathogens is gaining increasing acceptance. Objective: To evaluate a bacteriophage cocktail's effectiveness in reducing SE counts in an experimentally contaminated mayonnaise-like matrix. Methods: Homemade mayonnaise was contaminated with SE (103 CFU/ml) with equal volume to a matrix (1:1) treated with a bacteriophage cocktail (five phages, MOI 105), and stored at 21 °C for 24 and 72 h. Bacterial counts were performed to evaluate the bio-controlling activity of the cocktail and compared with a contaminated but not treated group. Results: Significant reductions (up to 3.75 log10 CFU/ml) were observed in the bacteriophage-treated groups (p<0.0001). Conclusions: These results demonstrate the effectiveness of bacteriophages as biocontrol agents for Salmonella Enteritidis in a raw-egg-derivative foodstuff. Further studies are needed to prove the reduction in an undiluted homemade mayonnaise.

Resumen Antecedentes: La Salmonella enterica, serovar Enteritidis (SE), es una de las principales causas de enfermedades transmitidas por alimentos en todo el mundo, asociadas principalmente al consumo de productos avícolas tales como los huevos. Diferentes métodos de control se han ensayado en el proceso de producción de huevos, pero no han sido capaces de reducir eficazmente los brotes de salmonelosis en las personas. Por esta razón, el uso de bacteriófagos para el control biológico de patógenos transmitidos por los alimentos está ganando cada vez más aceptación. Objetivo: Evaluar la eficacia de un cóctel de bacteriófagos para reducir los recuentos de SE en una matriz similar a la de mayonesa contaminada experimentalmente. Método: La mayonesa casera fue contaminada con SE (103 UFC/ml) en igual volumen que la matriz (1:1), tratada con una mezcla de bacteriófagos (cinco fagos, MOI 105), y almacenada a 21 °C por 24 y 72 h. Se realizaron recuentos bacterianos para evaluar la actividad biocontroladora de la mezcla y compararlos con un grupo contaminado, pero no tratado. Resultados: Se observaron reducciones significativas (hasta 3,75 log10 CFU/ml) en los grupos tratados con bacteriófagos (p<0,0001). Conclusiones: Estos resultados demuestran la efectividad del uso de bacteriófagos como agentes de biocontrol de Salmonella Enteritidis en un alimento crudo derivado del huevo. Sin embargo, se necesita realizar más estudios para comprobar la reducción en mayonesa casera no diluida.

Resumo Antecedentes: Salmonella enterica serovar Enteritidis (SE) é uma das principais causas de doenças transmitidas por alimentos em todo o mundo, principalmente associada ao consumo de produtos derivados de aves, como ovos. Diferentes métodos de controle foram implementados no processo de produção de ovos, mas não foram capazes de reduzir efetivamente os surtos nas pessoas. Por esse motivo, o uso de bacteriófagos para o controle biológico de patógenos de origem alimentar está ganhando crescente aceitação. Objetivo: Avaliar a eficácia de um coquetel de bacteriófagos na redução da contagem de SE em uma matriz experimentalmente semelhante a maionese contaminada. Método: A maionese caseira foi contaminada com SE (103 UFC/ml) no mesmo volume da matriz (1:1), tratada com uma mistura de bacteriófagos (cinco fagos, MOI 105) e armazenada a 21 °C por 24 e 72 h. As contagens bacterianas foram realizadas para avaliar a atividade de biocontrole da mistura e comparadas com um grupo contaminado, mas não tratado. Resultados: Reduções significativas (até 3,75 log10 UFC/ ml) foram observadas nos grupos tratados com bacteriófagos (p<0,0001). Conclusões: Esses resultados demonstram a eficácia do uso de bacteriófagos como agentes de biocontrole de Salmonella Enteritidis em alimentos crus derivados de ovos, mas são necessários mais estudos para verificar a redução da maionese caseira não diluída.

Predator preferences: a key to effective biological control design / Preferências do predador: a chave para um projeto de controle biológico eficaz

Objetctive: This experimental study aimed to assess the preference of Gambusia affinis to mosquito larvae of An.gambiae s.s., Cx. quinquefasciatus and Aedes aegypti. Method: Three Gambusia affinis were introduced in a glass container with a dimension of 45cm x 25cmx 25cm. Three larvae densities were used, 90 (30 larvae per species), 120 (40 larvae per species), and 180 (60 larvae per species). Each density experiment was set in triplicate and monitored after 1, 2, 3, and 24 hours. No fish food was added to the container for larvae. Results: Results have shown that in all times A. aegypti has been the most preferred species by Gambusia affinis. Among the tested species, A. aegypti was most prayed with time and in different densities. In mixed models including density, species, and time there was no significant difference among the species predation. Conclusion: Preliminary results have shown that the appropriate choice of predators for each mosquito species can have a great impact on bio-control to substantially complement existing tools.

Objetivo: avaliar a preferência de Gambusia affinis por larvas de mosquito de An. gambiae s.s., Cx. quinquefasciatus e Aedes aegypti. Método: Três Gambusia affinis foram introduzidos em um recipiente de vidro com dimensões de 45cm x 25cm x 25cm. Foram utilizadas três densidades de larvas, 90 (30 larvas por espécie), 120 (40 larvas por espécie) e 180 (60 larvas por espécie). Cada experimento de densidade foi estabelecido em triplicado e monitorado após 1, 2, 3 e 24 horas. Nenhum alimento de peixe foi adicionado ao recipiente com larvas. Resultados: Os resultados mostraram que em todos os tempos o A. aegypti foi a espécie mais preferida por Gambusia affinis. Entre as espécies testadas, A. aegypti foi a mais predada com o tempo e em diferentes densidades. Em modelos mistos incluindo densidade, espécie e tempo, não houve diferença significativa entre a predação por espécies. Conclusão: Os resultados preliminares mostraram que a escolha apropriada de predadores para cada espécie de mosquito pode ter um grande impacto no bio-controle para complementar substancialmente as ferramentas existentes.

Seasonal abundance of Henosepilachna vigintioctopunctata (Fab.) on Solanum melongena L. and natural occurrence of its two hymenopteran parasitoids

ABSTRACT The 28-spotted hadda beetle Henosepilachna vigintioctopunctata Fab. (Coleoptera: Coccinellidae) is a poly-phagous pest, commonly infesting solanacious crops including brinjal, Solanum melongena L. Upon its severe infestation on brinjal, it causes considerable damage to the foliage and also to the calyx of fruits. The studies were made to record the seasonal abundance of hadda beetle and identification of its natural enemies present in the region for two consecutive years. The pooled data for two years showed that the maximum number of H. vigintioctopunctata egg clusters on brinjal were recorded in the 27th (0.40 egg cluster/ plant), followed by grub population in 35th (3.78 grubs/ plant), pupae in 33rd and 39th (0.83 pupae/ plant) and adult beetles in 36th (5.48 adults/ plant) standard meteorological weeks, respectively. It was observed that the key meteorological factors had 35.9%, 87.3%, 66.8% and 81.9% effect on the abundance of egg clusters, grubs, pupae and adults respectively in summer planted brinjal crop. Two natural enemies of hadda beetle viz. Tetrastichus sp. (egg parasitoid) and Pediobius foveolatus (pupal parasitoid) were recorded. The maximum parasitisation by Tetrastichus sp. and P. foveolatus on the egg clusters and pupae was recorded 22.64% and 6.62% respectively, during the month of August (34th and 35th standard meteorological week respectively). Further, the morphometric parameters of these two adult parasitoids were recorded and greater morphometric variability was observed in P. foveolatus in comparison to Tetrastichus sp.

Laboratory efficacy of mycoparasitic fungi (Aspergillus tubingensis and Trichoderma harzianum) against tropical bed bugs (Cimex hemipterus) (Hemiptera: Cimicidae)

Objective To test the effectiveness of conidial spore formulations [Aspergillus tubingensis (A. tubingensis) and Trichoderma harzianum (T. harzianum)] against tropical bed bugs, Cimex hemipterus. Methods Spore formulations were made from two fungal strains, T. harzianum and A. tubingensis. The bed bugs were exposed to the conidial spores placed soaked onto a fabric cloth for 1 h and the mortality counts were recorded daily until 14 days. Results Mean survival times based on Kaplan–Meier survival analysis showed no significant differences between all the concentrations in both the fungal isolates: T. harzianum and A. tubingensis. However, the evaluation of both the isolates in terms of virulence resulted in low lethal hours in all the concentrations except for the high concentration of A. tubingensis (LT

Laboratory efficacy of mycoparasitic fungi (Aspergillus tubingensis and Trichoderma harzianum) against tropical bed bugs (Cimex hemipterus) (Hemiptera: Cimicidae)

Objective:To test the effectiveness of conidial spore formulations [Aspergillus tubingensis (A.tubingensis) and Trichoderma harzianum (T.harzianum)] against tropical bed bugs,Clnex hemipterus.Methods:Spore formulations were made from two fungal strains,T.harzianum and A.tubingensis.The bed bugs were exposed to the conidial spores placed soaked onto a fabric cloth for 1 h and the mortality counts were recorded daily until 14 days.Results:Mean survival times based on Kaplan-Meier survival analysis showed no significant differences between all the concentrations in both the fungal isolates:T.harzianum and A.tubingensis.However,the evaluation of both the isolates in terms of virulence resulted in low lethal hours in all the concentrations except for the high concentration ofA.tubingensis (LT50 =44.629 h) at the conidial exposure of 1 × 106 spores/mL.Rapid mortality of the bed bugs was observed from Day 6 to Day 12,ranging from 13％ to 90％ in all three concentrations of A.tubingensis.With reference to the T.harzianum exposure,the concentration of 1 × 104 spores/mL displayed a gradual increase in the percentage mortality of 90 on Day 14.Conclusions:Approaches to the bed bugs treatment should be explored in-depth using a natural biological agent like fungus especially A.tubingensis to reduce this pest population,in order to replace chemical methods.

Management of blight of bell pepper (Capsicum annuum var. grossum) caused by Drechslera bicolor

Abstract Sweet or bell pepper is a member of the Solanaceae family and is regarded as one of the most popular and nutritious vegetable. Blight, in the form of leaf and fruit blight, has been observed to infect bell pepper crops cultivated at the horticulture farm in Rajasthan College of Agriculture, Udaipur, India. Based on disease severity, we attempted to curb this newly emerged problem using different fungicides, plant extracts, bio-control agents, and commercial botanicals against the fungus in laboratory and pot experiments. Bio-control agent Trichoderma viride and plant growth promoting Rhizobacteria (PGPR) isolate Neist-2 were found to be quite effective against bell pepper blight. All evaluated fungicides, botanicals, commercial botanicals, and bio-control agents in vitro were further studied as seed dressers and two foliar sprays at ten days interval in pot experiments. The combinations of Vitavax, PGPR isolate Neist-2, and Mehandi extract were found to be very effective against bell pepper blight followed by Vitavax, T. viride, and Mehandi extract used individually. All treatments in the pot experiments were found to significantly reduce seedling mortality and enhance plant biomass of bell pepper. Thus, these experimental findings suggest that a better integrated management of bell pepper blight could be achieved by conducting field trials in major bell pepper- and chilli-cultivated areas of the state. Besides fungicides, different botanicals and commercial botanicals also seem to be promising treatment options. Therefore, the outcome of the present study provides an alternate option of fungicide use in minimizing loss caused by Drechslera bicolor.

El desafío de controlar las enfermedades transmitidas por alimentos: bacteriófagos como una nueva herramienta biotecnológica / The challenge of controlling foodborne diseases: bacteriophages as a new biotechnological tool

Foodborne diseases are an increasing public health issue, in which bacterial pathogens have a transcendental role. To face this situation, the food industry has implemented several control strategies, using in the last decade some biotechnological tools, such as direct application of bacteriophages on food, to effectively control bacterial pathogens. Their bactericidal and safe properties to humans and animals have been widely described in the literature, being nowadays some bacteriophage-based products commercially available. Despite this, there are so many factors that can interfere in their biocontrol effectiveness on food, therefore is essential to consider these factors before their application. Thus, the optimal bacterial reduction will be achieved, which would produce a safer food. This review discusses some factors to consider in the use of bacteriophages as biocontrol agents of foodborne pathogens, including historical background, taxonomy and biological description of bacteriophages, and also advantages, disadvantages, and considerations of food applications.

Las enfermedades transmitidas por alimentos son un creciente problema de salud pública, donde los agentes patógenos bacterianos juegan un rol trascendental. La industria alimentaria ha implementado diversas medidas de control para enfrentar esta situación, utilizando en la última década algunas herramientas biotecnológicas, como es la aplicación de bacteriófagos directamente en los alimentos. Sus propiedades exclusivamente bactericidas e inocuas para el hombre y los animales han sido descritas ampliamente en la literatura científica, existiendo a la fecha algunos productos comerciales disponibles en el mercado internacional. A pesar de esto, diversos son los factores que pueden influir en su efectividad bio-controladora en alimentos, por lo que conocer dichos factores resulta fundamental antes de considerar su aplicación. De esta manera, se logrará obtener la máxima actividad reductora de la carga bacteriana, generando así un alimento más seguro. Esta revisión aborda ciertos factores a considerar para el uso de bacteriófagos como agentes bio-controladores de patógenos alimentarios, incluyendo antecedentes históricos, taxonomía y descripción biológica de bacteriófagos, así como ventajas, desventajas y consideraciones de su aplicación en alimentos.

Lethal response of the dengue vectors to the plant extracts from family Anacardiaceae

Objective: To explore the larvicidal activities of different plant parts of Melanochyla fasciculiflora (. M. fasciculiflora), Gluta renghas (. G. renghas), Anacardium occidentale and Mangifera indica from family Anacardiaceae against the laboratory and field strains of dengue vectors Aedes aegypti and Aedes albopictus (. Ae. albopictus). Methods: Leaves and bark parts of study plants were collected from Taman Nageri, Bukit Pancor and Teluk Bahang National Park, Penang, Malaysia. Leaves and stem barks were separated, air dried, ground and extracted with methanol by Soxhlet apparatus. Crude extract was obtained by evaporating the extra solvent in rotary evaporator. The 4th instar larvae from laboratory and field strains were exposed to 50-1. 300 mg/L concentrations according to World Health Organization standard larval bioassay. Larval mortality was recorded after 24 h of exposure. Results: Highest larvicidal activity was exhibited by G. renghas bark extract against Ae. albopictus laboratory strain at 600 mg/L. G. renghas also showed the highest larvicidal activities for other strains as compared to other plant extracts, followed by Mangifera indica and M. fasciculiflora and Anacardium occidentale. Conclusions: Ae. albopictus has been found to be more susceptible as compare to Aedes aegypti in both laboratory and field strains in this study. G. renghas and M. fasciculiflora were tested for the first time and exhibited prompting larvicidal activities against dengue vectors. These results revealed that all the plants especially G. renghas and M. fasciculiflora have the higher larvicidal activities and can be used for the control of dengue vector as a new environment friendly, target specific and low cost phytochemical.

Lethal response of the dengue vectors to the plant extracts from family Anacardiaceae

Objective:To explore the larvicidal activities of different plant parts ofMelanochyla fasciculiflora(M. fasciculiflora),Gluta renghas(G. renghas),Anacardium occidentale and Mangifera indica from family Anacardiaceae against the laboratory and field strains of dengue vectorsAedes aegyptiandAedes albopictus(Ae. albopictus). Methods: Leaves and bark parts of study plants were collected from Taman Nageri, Bukit Pancor and Teluk Bahang National Park, Penang, Malaysia. Leaves and stem barks were separated, air dried, ground and extracted with methanol by Soxhlet apparatus. Crude extract was obtained by evaporating the extra solvent in rotary evaporator. The 4th instar larvae from laboratory and field strains were exposed to 50-1 300 mg/L concentrations according to World Health Organization standard larval bioassay. Larval mortality was recorded after 24 h of exposure. Results: Highest larvicidal activity was exhibited byG. renghas bark extract againstAe. albopictus laboratory strain at 600 mg/L.G. renghas also showed the highest larvicidal activities for other strains as compared to other plant extracts, followed byMangifera indica andM. fasciculilfora andAnacardium occidentale. Conclusions:Ae.albopictus has been found to be more susceptible as compare toAedes aegypti in both laboratory and field strains in this study.G. renghas andM. fasciculiflora were tested for the first time and exhibited prompting larvicidal activities against dengue vectors. These results revealed that all the plants especiallyG. renghas andM. fasciculilfora have the higher larvicidal activities and can be used for the control of dengue vector as a new environment friendly, target specific and low cost phytochemical.

Bio-control potential of Cladosporium sp. (MCPL - 461), against a noxious weed Parthenium hysterophorus L.

The phenological survey of Parthenium hysterophorus L., in and around the campus of Banaras Hindu University (BHU) was done for about two years (2004-06). During Nov. 2004, a few Parthenium plants were found diseased, and symptoms were restricted to the flowers, buds, and inflorescences. The disease causes sterility and reduces seed viability, which was observed with seed germination test from infected and healthy plants. The fungal pathogen was isolated and identified as Cladosporium sp. (MCPL-461). The severity of pathogen to the reproductive organs led to serious damages of the Parthenium plants. Thus in vitro and in vivo experiments were conducted to determine the bio-control potential of Cladosporium sp. (MCPL 461) against Parthenium weed. A combinatorial effort of Cladosporium sp. (MCPL 461) bio-control potential was evaluated with different culture media, incubation periods and spores strength. Spore suspension of 105 to 1012 spores ml-1 were used to spray on healthy Parthenium plants, and it was found that severe infection symptoms were appeared at 1010 to 1012 spores ml-1 suspension. LD50 was found at 107spores ml-1. To enhance the myco-herbicide activity 3% sucrose was added to the spore suspension, which further resolute the bio-control efficacy of the isolates. Only 20-30 % seeds of infected plants could germinate. However the safety of non-targeted and wild plants was also tested with Lantana camera, Chromolaena odorata and found that suspension up to 1012 spores ml-1 were not sufficient for disease outbreak in them.

QUORUM SENSING IN PLANT-ASSOCIATED BACTERIA / 微生物学通报

Bacterial N-Acyl-L-homoserine lactones (AHLs)-mediated quorum sensing is involved in the regulation of diverse biological functions. As the bacterial pathogen population density increases, AHLs concentration secreted by pathogen reaches a threshold and then interacts with their intercellular receptor and triggers expression of virulence genes. It is a promising approach to biologically control bacterial disease in plants and animals by manipulating bacterial AHL-quorum sensing with AHLs-degrading enzyme and AHL analogue.