The bacterial strains and plasmids used in this study are listed in Table 1 . S. suis strain SC-19 (streptomycin-resistant) of serotype 2 used in this study was isolated from a sick pig during the epidemic outbreak in Sichuan province of China in 2005 [37 (link)]. SC-19 and its genetically modified strains were grown in tryptic soy broth (TSB) or on tryptone soy agar (TSA) (Difco, France) supplemented with 10% fetal bovine serum (FBS) (Sijiqing, Hangzhou, China) at 37°C. For screening mutant strain ΔmsmK, erythromyein (90 μg/ml) was added. For construction of complementary strain CΔmsmK, erythromyein (90 μg/ml) and spectinomycin (100 μg/ml) were added when needed. Chemically defined medium (CDM) [38 (link)] supplemented with no sugar, or 1% of glucose, maltose, maltotriose, maltotetraose, raffinose, melibiose or glycogen as indicated was used for growth assays and Western blot. Bacteria cultured with CDM were grown at 37°C.
E. coli DH5α (Trans, China) was used as a host strain for cloning, and E. coli BL21 (DE3) (Trans) was used as a host strain to express His-tag fusion protein MsmK. Both were cultured in Luria-Bertani (LB) broth (Difco) or plated on LB agar plates at 37°C or 18°C.When appropriate, kanamycin (25 μg/ml) was added for bacterial selection.
Unless otherwise specified, all the antibiotics, chemicals and substrates were purchased from Biosharp (Hefei, China).
E. coli DH5α (Trans, China) was used as a host strain for cloning, and E. coli BL21 (DE3) (Trans) was used as a host strain to express His-tag fusion protein MsmK. Both were cultured in Luria-Bertani (LB) broth (Difco) or plated on LB agar plates at 37°C or 18°C.When appropriate, kanamycin (25 μg/ml) was added for bacterial selection.
Unless otherwise specified, all the antibiotics, chemicals and substrates were purchased from Biosharp (Hefei, China).
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