Pseudomonas-Saccharomyces interactions: Influence of fungal metabolism on bacterial physiology and survival

Julia D. Romano, Roberto Kolter

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Fungal-bacterial interactions are ubiquitous, yet their molecular basis is only poorly understood. In this study, a novel beneficial interaction between a strain of Pseudomonas putida and the fungus Saccharomyces cerevisiae was identified. When the bacteria were incubated alone in grape juice or in synthetic medium containing various concentrations of glucose, they lost viability rapidly during stationary phase. However, when the bacteria were incubated in these media in the presence of the fungus, their stationary phase survival improved dramatically. On agar plates containing glucose, the beneficial effects of the fungus were manifested in robust bacterial growth and exopolysaccharide production that led to visible mucoidy. In contrast, bacteria grew poorly and were nonmucoid in such media in the absence of the fungus. By using the available S. cerevisiae deletion library, yeast mutants that were unable to mediate this beneficial interaction were identified. These mutants revealed that the beneficial effect on bacterial physiology and survival was mediated by the ability of the fungus to metabolize the available glucose and consequent effects on the medium's pH. In natural environments where the concentration of glucose is high, it is likely that the presence of fungi has had profound beneficial effects on the physiology and survival of certain P. putida strains throughout their natural history.

Original languageEnglish (US)
Pages (from-to)940-948
Number of pages9
JournalJournal of bacteriology
Issue number3
StatePublished - Feb 2005

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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