Effects of Spi-1 and Spi-2 deletions on levels of secreted FlgM. (A) Secreted levels of FlgM were determined for strains carrying deletion mutant alleles of the either the Spi1 or Spi2 gene by quantitative Western blot analysis using anti-FlgM antibody to detect FlgM in the supernatant of the spent growth medium. Sec FlgM, secreted FlgM; WC FlgM, whole cellular FlgM; WC DnaK, whole cellular DnaK. P*, parent strain, TH18500 (ΔaraBAD1156::flgM+). (B) Relative levels of secreted FlgM.