Abstract
BackgroundDuring the infection process, bacteria are confronted with various stress factors including nutrient starvation. In an in vitro model, adaptation strategies of nutrient-starved brucellae, which are facultative intracellular pathogens capable of long-term persistence, were determined.ResultsLong-term nutrient starvation in a medium devoid of carbon and nitrogen sources resulted in a rapid decline in viability of Brucella suis during the first three weeks, followed by stabilization of the number of viable bacteria for a period of at least three weeks thereafter. A 2D-Difference Gel Electrophoresis (DIGE) approach allowed the characterization of the bacterial proteome under these conditions. A total of 30 proteins showing altered concentrations in comparison with bacteria grown to early stationary phase in rich medium were identified. More than half of the 27 significantly regulated proteins were involved in bacterial metabolism with a marked reduction of the concentrations of enzymes participating in amino acid and nucleic acid biosynthesis. A total of 70% of the significantly regulated proteins showed an increased expression, including proteins involved in the adaptation to harsh conditions, in regulation, and in transport.ConclusionsThe adaptive response of Brucella suis most likely contributes to the long-term survival of the pathogen under starvation conditions, and may play a key role in persistence.
Highlights
IntroductionBacteria are confronted with various stress factors including nutrient starvation
During the infection process, bacteria are confronted with various stress factors including nutrient starvation
Survival of B. suis under extreme starvation conditions Based on early work performed on M. tuberculosis [8], we have developed a simple nutrition starvation model to study the impact on long-term viability of the pathogen
Summary
Bacteria are confronted with various stress factors including nutrient starvation. In an in vitro model, adaptation strategies of nutrient-starved brucellae, which are facultative intracellular pathogens capable of long-term persistence, were determined. In the absence of an adequate long-term antibiotic treatment, acute human brucellosis (Malta fever) may relapse or turn into chronic disease [1,2]. During the acute phase of infection, brucellae are capable of replicating in the macrophages of the mammal host where they are found within a nutrient-poor vacuole. Viable brucellae are able to persist in the environment, and periods of survival in soil, manure and water have been determined, reaching up to 180, 240, and 150 days, respectively [16]. Soil may even be the natural habitat of the lately described species B. microti [17]
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