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Updated: Dec 8, 2025
Microtiter Dish Biofilm Formation Assay
Published on: January 30, 2011
Environmental pH is a key modulator of Staphylococcus aureus biofilm development under predation by the virulent
Lucía Fernández1,2, Diana Gutiérrez3,4, Pilar García3,5
1Instituto de Productos Lácteos de Asturias (IPLA-CSIC), Paseo Río Linares s/n, 33300, Villaviciosa, Asturias, Spain. lucia.fernandez@ipla.csic.es.
Abstract:
Previous work had shown that, in some Staphylococcus aureus strains, low concentrations of the virulent phage vB_SauM_phiIPLA-RODI (phiIPLA-RODI) promoted the formation of DNA-rich biofilms, whose cells exhibited significant transcriptional differences compared to an uninfected control. This study aimed to dissect the sequence of events leading to these changes. Analysis of phage propagation throughout biofilm development revealed that the number of phage particles increased steadily up to a certain point and then declined. This partial phage inactivation seemed to be a consequence of medium acidification due to glucose fermentation by the bacterium. Computer simulation of phage-host dynamics during biofilm development showed how even small differences in pH evolution can affect the outcome of phage infection. An acidic pH, together with successful phage propagation, was also necessary to observe the phage-associated changes in biofilm architecture and in the transcriptional profile of the bacterial population. Altogether, this study shows how the dynamics between phage and host can be tightly coordinated through an environmental cue, even in the context of a complex biofilm population.
Insights
Bacteriophage phiIPLA-RODI and Staphylococcus aureus biofilm formation are linked by pH. Acidic conditions, caused by bacterial fermentation, influence phage propagation and alter biofilm structure and gene expression.
Area of Science:
- Microbiology
- Bacteriology
- Molecular Biology
Background:
- Staphylococcus aureus biofilms are a significant clinical concern.
- Previous studies indicated that phage phiIPLA-RODI influences S. aureus biofilm formation and bacterial transcription.
- The precise mechanisms driving these phage-induced changes remained unclear.
Purpose of the Study:
- To elucidate the sequence of events linking phage phiIPLA-RODI infection to altered Staphylococcus aureus biofilm characteristics.
- To investigate the role of environmental factors, specifically pH, in phage-host dynamics within biofilms.
Main Methods:
- Monitoring phage propagation and bacterial transcriptional profiles during biofilm development.
- Utilizing computer simulations to model phage-host interactions under varying pH conditions.
- Assessing changes in biofilm architecture and bacterial gene expression in response to phage infection and pH.
Main Results:
- Phage phiIPLA-RODI particle numbers initially increased then declined during biofilm development, correlating with medium acidification from glucose fermentation.
- Computer simulations demonstrated the critical impact of pH evolution on phage infection outcomes.
- Acidic pH was essential for observing phage-mediated alterations in biofilm architecture and bacterial transcriptional profiles.
Conclusions:
- Phage-host dynamics in Staphylococcus aureus biofilms are modulated by environmental cues, particularly pH.
- Bacterial fermentation-induced acidification plays a key role in regulating phage propagation and subsequent biofilm modification.
- This study highlights a coordinated interaction between phage, host, and environment in complex microbial communities.
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