Journal: Frontiers in Microbiology
Article Title: SdiA, a Quorum-Sensing Regulator, Suppresses Fimbriae Expression, Biofilm Formation, and Quorum-Sensing Signaling Molecules Production in Klebsiella pneumoniae
doi: 10.3389/fmicb.2021.597735
Figure Lengend Snippet: K. pneumoniae cells lacking SdiA regulator reach maximum production of AI-2 QS signaling molecules earlier and present up-regulation of luxS and lrsR . (A) Cell-free supernatants were collected from wild-type and sdia :: kan R mutant strains cultured at the indicated O.D. and tested for AI-2 production by indirect measuring the level of bioluminescence induced in the V. campbellii MM32 reporter strain. The mutant strain reaches maximum production of AI-2 after 2 h of culture, while the wild-type and complemented strains reached maximum production of AI-2 only after 8 h of culture. The addition of AHL had no effect on the production of AI-2 molecules by the K. pneumoniae strains. (B) The absence of SdiA causes up-regulation of luxS and lsrR genes, which encode the AI-2 synthase and the LsrR repressor, respectively. No change in the expression of lsrB (receptor of AI-2 molecules) was observed between the wild-type and mutant strains. Gene expression analysis were performed by RT-qPCR on the wild-type and mutant K. pneumoniae strains cultured at O.D. 600 nm of 0.2 and 0.6. Error bars represent the standard deviation. Statistically significant differences between the strains were analyzed by multiple t -test (** p < 0.01; *** p < 0.001).
Article Snippet: For indirect measurements of AI-2 molecules produced by the K. pneumoniae strains we used the reporter strain Vibrio campbellii MM32 (ATCC ® BAA-1121 TM ).
Techniques: Mutagenesis, Cell Culture, Expressing, Gene Expression, Quantitative RT-PCR, Standard Deviation
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