Biofilm Formation by Clostridium ljungdahlii Is Induced by Sodium Chloride Stress: Experimental Evaluation and Transcriptome Analysis
C. ljungdahlii biofilms were grown in well plates by adding 200 mM NaCl to the medium. The medium was not swapped in control wells (left), while, after 3 days of incubation, the supernatant of all other wells was carefully removed to not disturb the biofilms. Fresh medium without NaCl addition (middle) or with 200 mM NaCl (right) was added to the wells (n = 3). One day after the swap of the medium (four days after the start of the experiment), the crystal violet assay (described in text) was performed on all wells. The pictures underneath the data bars show the corresponding, stained biofilms, before extraction with methanol. Remark that OD 600 nm values are given on a linear scale, while the A 570 nm values are on a logarithmic scale.