Bactericidal Effect of Entomopathogenic Bacterium Pseudomonas entomophila Against Xanthomonas citri Reduces Citrus Canker Disease Severity.

The bacterium Pseudomonas entomophila has been recognized as an exceptional species within the Pseudomonas genus, capable of naturally infecting and killing insects from at least three different orders. P. entomophila ingestion leads to irreversible gut damage resulting from a global blockage of translation, which impairs both immune and tissue repair systems in the insect intestine. In this study we isolated a P. entomophila bacterial strain from soil samples which displayed a strong activity against Xanthomonas citri subsp, citri (Xcc), the etiological agent of citrus canker disease. The antagonism potential of isolated bacteria against Xcc and its ability to reduce citrus canker severity was assessed both ex planta and in planta. Our findings show that pathogenicity assays in Citrus x limonia by pressure infiltration and spray with a mixture of P. entomophila and Xcc leaded to a significant reduction in the number of canker lesions in high susceptible citrus leaves, at 21 days post-infection. To the best of our knowledge this is the first report of antibacterial activity of P. entomophila against a phytopathogenic bacterium. Collective action of P. entomophila factors such as diketopiperazine production and the type 6 secretion system (T6SS) may be involved in this type of biological control of citrus canker. The results suggest that the P. entomophila strain could be a promising biocontrol agent acting directly against Xcc.

Uso de biomarcador histopatológico em brânquias de Centropomus undecimalis (Bloch, 1972) na avaliação da qualidade da água do Parque Ecológico Laguna da Jansen, São Luís - MA / Using histopathological biomarker in gills of Centropomus undecimalis (Bloch, 1972) in assessing the water quality at Ecological Park Laguna da Jansen, São Luís -MA

Com o objetivo de analisar a intensidade das alterações histológicas em brânquias de Centropomus undecimalis para avaliar a qualidade da água do Parque Ecológico Laguna da Jansen, em São Luís, Estado do Maranhão, coletaram-se exemplares de peixes no período chuvoso de 2012 e amostras de água nos períodos seco de 2011 e chuvoso de 2012 para análises físico-química e bacteriológica. Os resultados mostraram que a maioria dos parâmetros físico-químicos e bacteriológicos estava de acordo com os valores estabelecidos pela Resolução do CONAMA nº 357 de 2005. As alterações histológicas observadas foram: elevação do epitélio lamelar; proliferação excessiva de células dos epitélios filamentar e lamelar causando fusão total ou parcial das lamelas; alteração da estrutura das lamelas; hiperplasia das células mucosas; ruptura do epitélio lamelar; espessamento descontrolado do tecido proliferativo filamentar e lamelar e aneurismas de vários tamanhos. Também foi observada a presença de parasito em alguns exemplares. O Índice de Alteração Histológica (IAH) por indivíduo variou de 2 a 114. O valor médio do IAH obtido foi de 40,3, demonstrando que as brânquias dos indivíduos amostrados da espécie C. undecimalis apresentaram alterações de moderadas para severas no tecido. As alterações histológicas encontradas indicam que esses indivíduos desenvolveram mecanismos de defesa contra a ação de estressores presentes na água da laguna e a um provável desequilíbrio parasito-hospedeiro-ambiente associado à baixa qualidade do ambiente...

Aiming to analyze the intensity of the histological changes in the gills of Centropomus undecimalis to assess the water quality at Ecological Park of the Laguna da Jansen, in São Luís, State of Maranhão, specimens of fish were collected during the rainy season of 2012 and water samples during the dry season in 2011 and rainy season in 2012 for physical-chemical and bacteriological analyses. The results showed that most of the physical-chemical and bacteriological parameters analyzed agreed with the values established by CONAMA Resolution nº 357 of 2005. The histological changes were elevation of the lamellar epithelium, excessive cell proliferation of the filamentum and lamellar epithelium causing total or partial melting of the lamellar; changing the structure of the lamellar, hyperplasia of mucous cells, disruption of the lamellar epithelium, uncontrolled proliferative tissue filamentum thickening and lamellar and aneurysms in various sizes. We noted the presence of parasites in some samples. The Index Histological Amendment (IAH) per individual ranged from 2 to 114. The mean IAH obtained was 40.3, demonstrating that the gills of the individuals of the C. undecimalis species showed moderate to severe changes in the tissue. The histological findings indicate that these individuals have developed defense mechanisms against the action of stressors present in the water of the Laguna da Jansen and a probable parasite-host-environment imbalance associated with the environment's low quality...

Detecção de Salmonella Albany, Staphylococcus coagulase positivos e micro-organismos mesófilos em carcaças de frango in natura / Decteccion of Salmonella Albany, Coagulase positive Staphylococcus e mesophilic microrganisms in carcasses chicken in natura

Com o objetivo de avaliar as condições higiênico-sanitárias das carcaças de frango in natura comercializadas em mercados públicos do Município de São Luís, MA, foram colhidas quarenta amostras de carcaças de frango e analisadas quanto à pesquisa de Salmonella spp., Staphylococcus coagulase positivos e contagem padrão de micro-organismos mesófilos pelos métodos convencionais. Do total de amostras analisadas, 18 (45%) apresentaram contaminação por Staphylococcus coagulase positivos, 5 (12,5%) estavam contaminadas por Salmonella spp., identificadas como Salmonella Albany. A contagem padrão de micro-organismos mesófilos variou de 103 a 107 UFC/g no alimento analisado. Os resultados obtidos indicam que as condições higiênico-sanitárias das carcaças de frango in natura analisadas são insatisfatórias e que este produto pode ser um importante veículo de toxi-infecção alimentar.

The objective of this study was to evaluate the hygienic-sanitary conditions of in natura broiler carcasses commercialized in the market from São Luiz City, MA. Forty samples were collected and analyzed to research of Salmonella spp., coagulase positive Staphylococcus and of mesophilic microorganisms count. Among the analyzed samples, eighteen (45%) were contaminated with coagulase positive Staphylococcus, five (12,5%) were contaminated with Salmonella sp, being identified Salmonella Albany and counting of 103 to 107 UFC/g of mesophilic microorganisms. The results showed the hygienic-sanitary conditions samples analyzed were unsatisfactory and the consumption of this products can lead to an intoxication.

Comparative analyses of the complete genome sequences of Pierce's disease and citrus variegated chlorosis strains of Xylella fastidiosa.

Xylella fastidiosa is a xylem-dwelling, insect-transmitted, gamma-proteobacterium that causes diseases in many plants, including grapevine, citrus, periwinkle, almond, oleander, and coffee. X. fastidiosa has an unusually broad host range, has an extensive geographical distribution throughout the American continent, and induces diverse disease phenotypes. Previous molecular analyses indicated three distinct groups of X. fastidiosa isolates that were expected to be genetically divergent. Here we report the genome sequence of X. fastidiosa (Temecula strain), isolated from a naturally infected grapevine with Pierce's disease (PD) in a wine-grape-growing region of California. Comparative analyses with a previously sequenced X. fastidiosa strain responsible for citrus variegated chlorosis (CVC) revealed that 98% of the PD X. fastidiosa Temecula genes are shared with the CVC X. fastidiosa strain 9a5c genes. Furthermore, the average amino acid identity of the open reading frames in the strains is 95.7%. Genomic differences are limited to phage-associated chromosomal rearrangements and deletions that also account for the strain-specific genes present in each genome. Genomic islands, one in each genome, were identified, and their presence in other X. fastidiosa strains was analyzed. We conclude that these two organisms have identical metabolic functions and are likely to use a common set of genes in plant colonization and pathogenesis, permitting convergence of functional genomic strategies.

Comparison of the genomes of two Xanthomonas pathogens with differing host specificities.

The genus Xanthomonas is a diverse and economically important group of bacterial phytopathogens, belonging to the gamma-subdivision of the Proteobacteria. Xanthomonas axonopodis pv. citri (Xac) causes citrus canker, which affects most commercial citrus cultivars, resulting in significant losses worldwide. Symptoms include canker lesions, leading to abscission of fruit and leaves and general tree decline. Xanthomonas campestris pv. campestris (Xcc) causes black rot, which affects crucifers such as Brassica and Arabidopsis. Symptoms include marginal leaf chlorosis and darkening of vascular tissue, accompanied by extensive wilting and necrosis. Xanthomonas campestris pv. campestris is grown commercially to produce the exopolysaccharide xanthan gum, which is used as a viscosifying and stabilizing agent in many industries. Here we report and compare the complete genome sequences of Xac and Xcc. Their distinct disease phenotypes and host ranges belie a high degree of similarity at the genomic level. More than 80% of genes are shared, and gene order is conserved along most of their respective chromosomes. We identified several groups of strain-specific genes, and on the basis of these groups we propose mechanisms that may explain the differing host specificities and pathogenic processes.