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Free keywords:
bacterial mixed culture, population dynamics, cystic fibrosis, Ceftazidime, phenazine synthesis
Abstract:
To improve the understanding of microbial communities, experiments have to be performed, investigating community interactions. Therefore, a bacterial mixed culture was analyzed during batch cultivations with and without addition of the antibiotic Ceftazidime. The community was composed of Burkholderia cepacia, Pseudomonas aeruginosa, and Staphylococcus aureus, pathogens causing infections in cystic fibrosis patients. Gel-based proteomics and mass-spectrometry were used to obtain qualitative and quantitative proteomic data. Proteomic tracking, an approach for relative quantification of species-specific population dynamics of mixed cultures, was developed. During cultivation P. aeruginosa became dominant within the mixed culture while S. aureus was inhibited in growth. Analysis of samples - taken along cultivation - revealed about 270 differentially expressed proteins. Some of those proteins related to bacterial interactions, response to antibiotic treatment, and metabolic shifts. For instance, the enzymes PhzS and PhzG2 indicated the production of the antibiotic pigment pyocyanine by P. aeruginosa which is related to oxidative stress and therefore, might inhibit growth of S. aureus. Overall, the strategy applied not only allows species-specific tracking of the community composition but also provides valuable insights into the behavior of mixed cultures.
Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim [accessed November 2nd 2012]
