Navegando por Palavras-chave "Bacteriophages"

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    Atenuação viral em solos tropicais
    (Universidade Federal de São Paulo, 2016-04-04) Galvez, Margarita Nuche [UNIFESP]; Freitas, Juliana Gardenalli de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Groundwater contamination by viruses is an important threat to public health, however this type of contaminant can be significantly attenuated by viral adsorption and inactivation. Since groundwater is needed for water supply, understanding and quantifying these processes is important to define strategies to minimize risks to human health. The occurrence of these processes depends on several factors and few studies have evaluated the behavior of viruses in tropical soils. In this context, this work aims to assess the transport and behavior of viruses in two soils of high occurrence in Brazil: a Typic Hapludox and an Udoxic Quartzipsamment. The ?X174 bacteriophage was selected for quantifying viral attenuation, because it is an useful substitute for human enteric viruses. Laboratory experiments were conducted injecting a pulse of bacteriophages suspended in water into soil columns. The obtained results were compared with a non-reactive tracer (bromide) and an inert material (glass beads). The Typic Hapludox showed higher viral attenuation capacity (>99,997%) than the Udoxic Quartzipsamment (>99,982%). The dominant processes were adsorption in the Typic Hapludox (up to 80.98%) and inactivation in the Udoxic Quartzipsamment (up to 83.17%). The bacteriophage was transported at a higher velocity than bromide tracer, due to exclusion processes. Mean pH values (?5) promoved electrostatic adsorption of phage to soil, but reduction in acidity increased phage release and transport was facilitated in some tests by co-transport mechanisms. Therefore, the presence of Typic Hapludox and Udoxic Quartzipsamment can result in significant protection of groundwater quality for viral contamination. However, more laboratory research is needed to examine the impact of other environmental factors and also field tests to help determine wellhead protection zones, to ensure safety of supply.
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    Characterization of bacteriophages infecting clinical isolates of Pseudomonas aeruginosa stored in a culture collection
    (Associação Brasileira de Divulgação Científica, 2013-08-13) Zanetti, C.c.s.; Mingrone, R.c.c.; Kisielius, J.j.; Ueda-ito, M.; Pignatari, Antonio Carlos Campos [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Instituto Adolfo Lutz Nucleo de Microscopia Eletronica
    Some clinical isolates of Pseudomonas aeruginosa stored in our culture collection did not grow or grew poorly and showed lysis on the culture plates when removed from the collection and inoculated on MacConkey agar. One hypothesis was that bacteriophages had infected and killed those clinical isolates. To check the best storage conditions to maintain viable P. aeruginosa for a longer time, clinical isolates were stored at various temperatures and were grown monthly. We investigated the presence of phage in 10 clinical isolates of P. aeruginosa stored in our culture collection. Four strains of P. aeruginosa were infected by phages that were characterized by electron microscopy and isolated to assess their ability to infect. The best condition to maintain the viability of the strains during storage was in water at room temperature. Three Siphoviridae and two Myoviridae phages were visualized and characterized by morphology. We confirmed the presence of bacteriophages infecting clinical isolates, and their ability to infect and lyse alternative hosts. Strain PAO1, however, did not show lysis to any phage. Mucoid and multidrug resistant strains of P. aeruginosa showed lysis to 50% of the phages tested.