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Published on: October 9, 2016
Cholate-stimulated biofilm formation by Lactococcus lactis cells
Arsalan Haseeb Zaidi1, Patrick J Bakkes, Bastiaan P Krom
1Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and the Kluyver Centre for Genomics of Industrial Fermentation, University of Groningen, Nÿenborgh 7, 9747 AG Groningen, Netherlands.
Lactococcus lactis lacking the LmrCD transporter reacquires bile acid resistance through cell surface changes. This leads to increased hydrophilicity and biofilm formation, enhancing survival in cholate environments.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Bile acid resistance in Lactococcus lactis is primarily mediated by the ABC-type multidrug transporter LmrCD.
- Deletion of lmrCD genes results in loss of bile acid resistance.
Purpose of the Study:
- To investigate the mechanism of acquired bile acid resistance in Lactococcus lactis lacking the LmrCD transporter.
- To understand the role of cell surface alterations and biofilm formation in non-transporter-based resistance.
Main Methods:
- Genetic deletion of lmrCD genes in Lactococcus lactis.
- Phenotypic analysis of bile acid resistance and cell surface properties (contact angle measurements).
- Assessment of biofilm formation on polystyrene surfaces under varying cholate concentrations.
Main Results:
- Lactococcus lactis cells lacking LmrCD (ΔlmrCD(r) strain) reacquired bile acid resistance.
- Resistance was linked to increased cell surface hydrophilicity and a tendency to flocculate.
- Subinhibitory cholate concentrations stimulated biofilm formation in ΔlmrCD(r) cells, with enhanced extracellular polymeric substance production.
- Biofilm cells exhibited high resistance to bile acids.
Conclusions:
- Non-transporter-based bile acid resistance in Lactococcus lactis involves significant cell surface alterations.
- These alterations promote biofilm formation, which confers enhanced resistance to bile acids.
- The study highlights an alternative resistance strategy independent of efflux pumps.
