Population dynamics of a dual Pseudomonas putida–Pseudomonas fluorescens biofilm in a capillary bioreactor

Abstract

Most biofilm studies employ single species, yet in nature biofilms exist as mixed cultures, with inevitable effects on growth and development of each species present. To investigate how related species of bacteria interact in biofilms, two Pseudomonas spp., Pseudomonas fluorescens and Pseudomonas putida, were cultured in capillary bioreactors and their growth measured by confocal microscopy and cell counting. When inoculated in pure culture, both bacteria formed healthy biofilms within 72 h with uniform coverage of the surface. However, when the bioreactors were inoculated with both bacteria simultaneously, P. putida was completely dominant after 48 h. Even when the inoculation by P. putida was delayed for 24 h, P. fluorescens was eliminated from the capillary within 48 h. It is proposed that production of the lipopeptide putisolvin by P. putida is the likely reason for the reduction of P. fluorescens. Putisolvin biosynthesis in the dual-species biofilm was confirmed by mass spectrometry.

Keywords:

• Detachment
• mixed-species biofilm
• lipopeptide

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the European Research Council (ERC) [grant number 278530]; and by the Science Foundation Ireland [grant number 15/IA/3008].