Environmental Stress-Induced Bacterial Lysis and Extracellular DNA Release Contribute to Campylobacter jejuni Biofilm Formation

Supplemental material

  • Supplemental file 1 -

    Supplemental Materials and Methods: construction of C. jejuni F38011 ΔspoT and ΔrecA mutant strains, construction of C. jejuni F38011 spoT and recA complementary strains, crystal violet biofilm assay, fabrication of microfluidic “lab-on-a-chip” platform for biofilm formation, atomic force microscopy, real-time qPCR analysis of gene expression; schematic illustration of the fabrication of microfluidic “lab-on-a-chip” platform (Fig. S1); Raman peaks derived from the microfluidic substrate had no overlap with the peaks derived from C. jejuni F38011 biofilm (Fig. S2); the mutations on flaA and flaB significantly decreased the motility of C. jejuni F38011, while the mutations on spoT or recA had no influence on the motility of C. jejuni F38011 (Fig. S3); autolysis level of C. jejuni induced by Triton X-100 was significantly higher than that of S. Typhimurium SL1344, and autolysis level had no significant difference among C. jejuni F38011 wild type and its spoT, recA, and flaAB deletion mutants (Fig. S4); the length of the DNA fragment present in C. jejuni during biofilm formation was similar to that of genomic DNA extracted from C. jejuni F38011 planktonic cells (Fig. S5); expression of flaA and flaB in C. jejuni F38011 wild type and its spoT and recA deletion mutants was upregulated only at the first day of biofilm formation under aerobic condition (Fig. S6); topographic images of C. jejuni F38011 biofilms confirmed that DNase I treatment disrupted biofilm structure and dispersed encased C. jejuni F38011 cells (Fig. S7); biofilm formation by C. jejuni F38011 complementary strains including spoT, recA, and flaAB under optimal condition (Fig. S8); bacterial strains and plasmid used in the current study (Table S1); primers used in the current study (Table S2); Raman band assignments for C. jejuni biofilm formed in the microfluidic platform (Table S3); legend to Video S1.

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  • Supplemental file 2 -

    C. jejuni-Salmonella dual-species biofilm (Video S1).

    AVI, 1.3M