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Optimization of Streptococcus agalactiae Biofilm Culture in a Continuous Flow System for Photoinactivation Studies
Michal K Pieranski1, Michal Rychlowski2, Mariusz Grinholc1
1Laboratory of Photobiology and Molecular Diagnostics, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, 80-307 Gdansk, Poland.
Insights
This study optimized Streptococcus agalactiae biofilm growth conditions for photoinactivation research. Rose Bengal-mediated photoinactivation effectively eradicated these biofilms without harming human cells.
Area of Science:
- Microbiology
- Biotechnology
- Medical Research
Background:
- Streptococcus agalactiae causes neonatal mortality through infections like meningitis and sepsis.
- Bacterial biofilm formation is a key factor in treatment failure and recurrent infections.
- Optimizing S. agalactiae biofilm culture is crucial for developing effective antimicrobial strategies.
Purpose of the Study:
- To optimize culture conditions for Streptococcus agalactiae biofilm growth.
- To evaluate the efficacy of Rose Bengal-mediated photoinactivation on S. agalactiae biofilms.
- To establish a reliable biofilm model for future antibacterial studies.
Main Methods:
- Compared biofilm production of four S. agalactiae strains in four media using crystal violet staining.
- Evaluated stationary microtiter plate cultures and continuous flow cultures in a CDC Biofilm Reactor.
- Applied Rose Bengal-mediated photoinactivation to established biofilm models.
Main Results:
- Identified optimal conditions for stable and reproducible S. agalactiae biofilm growth in continuous flow.
- Demonstrated efficient eradication of S. agalactiae biofilms using Rose Bengal photoinactivation.
- Confirmed that photoinactivation is not cytotoxic or phototoxic to human keratinocytes.
Conclusions:
- Optimized continuous flow conditions facilitate reliable S. agalactiae biofilm cultivation for research.
- Rose Bengal photoinactivation presents a promising, non-toxic method for eradicating S. agalactiae biofilms.
- The developed biofilm model is suitable for photoinactivation assays and other antibacterial investigations.
Abstract:
Streptococcus agalactiae is a relevant cause of neonatal mortality. It can be transferred to infants via the vaginal tract and cause meningitis, pneumonia, arthritis, or sepsis, among other diseases. The cause of therapy ineffectiveness and infection recurrence is the growth of bacteria as biofilms. To date, several research teams have attempted to find a suitable medium for the cultivation of S. agalactiae biofilms. Among others, simulated vaginal fluid has been used; however, biofilm production in this medium has been found to be lower than that in tryptic soy broth. We have previously shown that S. agalactiae can be successfully eradicated by photoinactivation in planktonic culture, but there have been no studies on biofilms. The aim of this study was to optimize S. agalactiae biofilm culture conditions to be used in photoinactivation studies. We compared biofilm production by four strains representing the most common serotypes in four different broth media with crystal violet staining. Then, we evaluated stationary biofilm culture in microtiter plates and biofilm growth in a CDC Biofilm Reactor® (BioSurface Technologies, Bozeman, MT, USA) under continuous flow conditions. Subsequently, we applied Rose Bengal-mediated photoinactivation to both biofilm models. We have shown that photoinactivation is efficient in biofilm eradication and is not cyto/phototoxic to human keratinocytes. We found conditions allowing for stable and repetitive S. agalactiae biofilm growth in continuous flow conditions, which can be successfully utilized in photoinactivation assays and potentially in all other antibacterial studies.
