Fig. 3

S-layer genes are not essential for the S. islandicus cell survival. a Genomic context of S-layer genes in the genetic host and mutant strains. Relative positions of primers used to confirm S-layer gene deletions are labelled with small arrows. b PCR verification of ΔslaA, ΔslaB, and ΔslaAB mutants with two primer sets, which bind the flanking and internal regions of S-layer genes, respectively. Expected sizes of amplicons can be found in Supplementary Table 8. L (lanes 1, 6, and 12) indicates the 2-Log DNA Ladder (NEB, USA). Blank (lane 11) denotes that no sample was loaded in the well. c Growth profiles of RJW004 (wild type), ΔslaA, ΔslaB, and ΔslaAB mutant strains. Wild-type and S-layer gene knockout strains were cultivated at pH 3.3, 76 °C for 11 days in DY liquid medium supplemented with uracil and agmatine without shaking. Cell culture growth was monitored by optical density measurements at 600 nm every 12 or 24 h. Error bars represented standard deviations from three independent experiments