Growth capacity of thermotolerant campylobacters in culture media supplemented with pig and cow blood

In this work 60 thermotolerant Campylobacter strains (37 C. jejuni and 23 C. coli) isolated from the cows, pigs, chickens and ducks (15 strains of each type of animal) were used to establish their growth capacity on media containing cow or swine blood as potential substitutes of sheep or horse blood. The growth capacity was assessed by viable counts on cow and swine blood media, using the modified Miles and Misra method. Campylobacter strains showed better growth in the media supplemented with pig or sheep blood than with cow blood. Thus, the use of pig blood could be a supplement for Campylobacter culture medium, when there was no availability of sheep or horse blood.

Na cidade de Iquitos (Região Amazônica do Peru), tanto o sangue de carneiro quanto o de eqüino, ambos recomendados como suplemento nos meios de cultura para Campylobacter, são difíceis de encontrar. No entanto, sangues de bovino e de suíno são de fácil disponibilidade. Por esta razão, 60 amostras de Campylobacter termotolerantes (37 C. jejuni e 23 C. coli) isoladas de bovinos, suínos, frangos e patos (15 amostras de cada animal) foram utilizadas para estabelecer sua capacidade de crescimento em meios de cultura contendo sangue de bovino ou de suíno como potenciais substitutos do sangue de carneiro ou de eqüino. A capacidade de crescimento foi estabelecida através da contagem de células viáveis utilizando o método de Miles e Misra modificado. Todas as amostras de Campylobacter mostraram melhor crescimento em meios suplementados com sangue de eqüino ou de suíno. Estes resultados permitem propor o uso de sangue de suíno como suplementos em meios de cultura para Campylobacter.

La sangre de cerdo y de vaca como substitutos de la sangre de oveja o de caballo en medios de cultivo para campylobacters termotolerantes / The pig's blood and cow's blood substitutes sheep or horse culture media for thermotolerant campylobacters

En la ciudad de Iquitos (ubicada en la Amazonía peruana), la sangre de oveja y de caballo, uno de los suplementos recomendados para los medios de cultivo de campylobacters termotolerantes, no son tan disponibles como la sangre de cerdo y de vaca. Por ello, se estudió la capacidad de crecimiento de 60 cepas de Campylobacter termotolerantes (37 C. jejuni y 23 C. coli), usando sangre de vaca y de cerdo como potenciales substitutos de la sangre de oveja o de caballo. Estas cepas fueron aisladas de vacas, cerdos, pollos y patos (15 cepas de cada tipo de animal). Recuentos viables fueron realizados empleando el método de Miles y Misra, modificado. Las cepas de Campylobacter mostraron mayor crecimiento en presencia de sangre de cerdo o de oveja que con sangre de vaca; por lo que se sugiere el uso de sangre de cerdo como un suplemento de los medios de cultivo para Campylobacter, cuando no existe disponibilidad de sangre de oveja o de caballo.

In Iquitos (capital city of the Peruvian Amazon), sheep and horse blood, one of the recommended supplements for thermo tolerant campylobacters in growing environments, are difficult to obtain in comparison to pig and cow blood. Therefore, the growing capacity of 60 thermo tolerant Campylobacter strains (37 C. jejuni and 23 C. coli) using cow and pig blood as potential substitutes for sheep or horse blood, was studied. The strains were isolated from cows, pigs, chickens and ducks (15 strains of each animal). Accountable measure were used applying a modified Miles and Misra method. Compylobacter strains showed better growth in presence of pig or sheep blood in comparison with cow blood, so, we suggest the use of pig blood as a supplemet in the Campylobacter growing environment, when there is no availability of sheep or horse blood.

Functional characterization of the Bradyrhizobium japonicum modA and modB genes involved in molybdenum transport.

A modABC gene cluster that encodes an ABC-type, high-affinity molybdate transporter from Bradyrhizobium japonicum has been isolated and characterized. B. japonicum modA and modB mutant strains were unable to grow aerobically or anaerobically with nitrate as nitrogen source or as respiratory substrate, respectively, and lacked nitrate reductase activity. The nitrogen-fixing ability of the mod mutants in symbiotic association with soybean plants grown in a Mo-deficient mineral solution was severely impaired. Addition of molybdate to the bacterial growth medium or to the plant mineral solution fully restored the wild-type phenotype. Because the amount of molybdate required for suppression of the mutant phenotype either under free-living or under symbiotic conditions was dependent on sulphate concentration, it is likely that a sulphate transporter is also involved in Mo uptake in B. japonicum. The promoter region of the modABC genes has been characterized by primer extension. Reverse transcription and expression of a transcriptional fusion, P(modA)-lacZ, was detected only in a B. japonicum modA mutant grown in a medium without molybdate supplementation. These findings indicate that transcription of the B. japonicum modABC genes is repressed by molybdate.

The Bradyrhizobium japonicum napEDABC genes encoding the periplasmic nitrate reductase are essential for nitrate respiration.

The napEDABC gene cluster that encodes the periplasmic nitrate reductase from Bradyrhizobium japonicum USDA110 has been isolated and characterized. napA encodes the catalytic subunit, and the napB and napC gene products are predicted to be a soluble dihaem c and a membrane-anchored tetrahaem c-type cytochrome, respectively. napE encodes a transmembrane protein of unknown function, and the napD gene product is a soluble protein which is assumed to play a role in the maturation of NapA. Western blots of the periplasmic fraction from wild-type cells grown anaerobically with nitrate revealed the presence of a protein band with a molecular size of about 90 kDa corresponding to NapA. A B. japonicum mutant carrying an insertion in the napA gene was unable to grow under nitrate-respiring conditions, lacked nitrate reductase activity, and did not show the 90 kDa protein band. Complementation of the mutant with a plasmid bearing the napEDABC genes restored both nitrate-dependent anaerobic growth of the cells and nitrate reductase activity. A membrane-bound and a periplasmic c-type cytochrome, with molecular masses of 25 kDa and 15 kDa, respectively, were not detected in the napA mutant strain incubated anaerobically with nitrate, which identifies those proteins as the NapC and the NapB components of the B. japonicum periplasmic nitrate reductase enzyme. These results suggest that the periplasmic nitrate reductase is the enzyme responsible for anaerobic growth of B. japonicum under nitrate-respiring conditions. The promoter region of the napEDABC genes has been characterized by primer extension. A major transcript initiates 66.5 bp downstream of the centre of a putative FNR-like binding site.

Control biológico del "cogollero del maíz" Spodoptera frugiperda, (Lepidoptera; Noctuidae) con el baculovirus sfvpn, en Iquitos-Perú / Biological control of \"cogollero corn\" Spodoptera frugiperda (Lepidoptera; Noctuidae) with the baculovirus sfvpn in Iquitos-Peru

Con el propósito de encontrar una alternativa al control químico del "cogollero del maíz" Spodoptera frugiperda, principal plaga para el cultivo del maíz (Zea mays), se estudió la posibilidad de utilizar como controlador biológico de esta plaga, al baculovirus SfVPN (Virus de Poliedrosis Nuclear de Spodoptera frugiperda). Utilizando larvas del 3er estadío se comprobó que es un eficiente controlador biológico, determinándose que la dosis letal media fue de 49,653 cuerpos de inclusión (CI)/larva, con un promedio de tiempo letal medio (TL50) de 6.5 más menos 0.5 días. Asímismo, el número de CI del SfVPN producidos por una larva de 5to estadío fue de 5.4X10 CI/larva, y de 6to estadío fue de 7.3X10 CI/larva, constituyéndose estos estadíos en buenas productoras de virus para formulaciones de insecticidas biológicos. Se propone, por tanto, el empleo del SfVPN como una alternativa para el control de Spodoptera frugiperda.

Carriage of the classical thermotolerant campylobacters in health domestic animals from Earstern Peru

Com o objetivo de conhecer a importancia dos animais domesticos como reservatorios naturais dos classicos campylobacters termotolerantes, amostras de fezes foram obtidas de mamiferos e aves do leste do Peru e imediatamente colocadas num meio de enriquecimento. Tecnicas convencionais foram utilizadas para identificar C. jejuni ssp. jejuni, C. coli e C. lari. Campylobacter foi isolado em 26,5 por cento dos animais estudados, sendo C. jejuni ssp. jejuni biovar I o mais frequente (8,9 por cento). O frango foi o reservatorio mais importante destes microorganismos (54,0 por cento).

Aislamiento de especies termotolerantes de Campylobacter en dos poblaciones de pollos criados con y sin confinamiento / Isolation of thermotolerant Campylobacter species from two populations of chickens bred in confinement and at liberty

Estuda a freqüência de isolamento de Campylobacter spp. em frangos domésticos e frangos mantidos em confinamento permanente, na cidade de Iquitos (Peru). Campylobacter spp. foi isolado em 54,0 por cento no primeiro grupo e 35,0 por cento no segundo (p<0,005). Das espécies termotolerantes clássicas, as mais freqüentes foram C. jejuni e C. coli. A presença de C. Iari nessas aves, assinala a importância delas como reservatório natural desse microrganismo

Chicken as potential contamination source of Campylobacter lari in Iquitos, Peru

Com objetivo de conhecer a importancia dos frangos como reservatorio natural de Campylobacter lari na cidade de Iquitos, Peru, foram estudadas amostras cloacais obtidas de 200 aves. Cada amostra foi semeada em meio de enriquecimento semi-solido e no agar de Skirrow modificado. C. lari foi isola do em 21(10,5 por cento) amostras. Destes, 58,8 (por cento) corresponderam ao biotipo I e 41,2 (por cento) ao biotipo II do esquema de Lior. Os resultados obtidos sugerem que os frangos podem ser um importante reservatorio de C. lari em Iquitos, Peru.