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Master's Dissertation
DOI
10.11606/D.87.2018.tde-25092018-154659
Document
Author
Full name
Gabriel Guarany de Araujo
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2017
Supervisor
Committee
Galante, Douglas (President)
Artaxo Netto, Paulo Eduardo
Pellizari, Vivian Helena
Title in Portuguese
Resposta biológica de Pseudomonas syringae ao ambiente atmosférico.
Keywords in Portuguese
Pseudomonas
Atmosfera
Microbiologia ambiental
Nucleação de gelo
Radiação ultravioleta
Abstract in Portuguese
Pseudomonas syringae produz núcleos de gelo biológicos de grande eficiência. Bioaerossóis destas células tem potencial de participar na glaciação de nuvens, podendo influenciar a precipitação. Foram estudadas como as condições as quais P. syringae está sujeita em suspensão na atmosfera afetam sua sobrevivência e sua atividade de nucleação de gelo. Duas cepas foram testadas, e ambas apresentaram baixa tolerância ao UV-C e ao UV-B, mas exibiram uma maior resistência quando expostas a um espectro semelhante ao encontrado no ambiente. A atividade de congelamento de uma das cepas (pv. syringae) não foi afetada pelo UV, enquanto que para a outra (pv. garcae) houve uma redução moderada. Em resposta à dessecação, pv. garcae foi substancialmente mais resistente que pv. syringae. Isto também afetou a nucleação de gelo das cepas. Em ensaios adicionais, estas bactérias foram expostas em um voo de balão estratosférico, e a uma simulação em laboratório das condições no topo da troposfera. Nestes dois experimentos, sobreviventes protegidos do UV foram recuperados.
Title in English
Biological response of Pseudomonas syringae to the atmospheric environment.
Keywords in English
Pseudomonas
Atmosphere
Environmental microbiology
Ice nucleation
Ultraviolet radiation
Abstract in English
Pseudomonas syringae produces biological ice nuclei of great efficiency. Bioaerosols of these cells have the potential to take part in cloud glaciation, possibly influencing the precipitation. It was studied how the conditions to which P. syringae is subjected while in suspension in the atmosphere affect its survival and its ice nucleation activity. Two strains were tested, and both showed a low tolerance to UV-C and UV-B, but exhibited a higher resistance when exposed to a spectrum similar to the one found in the environment. The freezing activity of one of the strains (pv. syringae) was not affected by the UV, while that for the other (pv. garcae) there was a moderate reduction. In response to desiccation, pv. garcae was substantially more resistant than pv. syringae. This also affected the ice nucleation by the strains. In additional assays, these bacteria were exposed in a stratospheric balloon flight, and to a laboratory simulation of the conditions at the top of the troposphere. After these two experiments, survivors protected from the UV were recovered.
 
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Publishing Date
2018-09-25
 
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