Table 3 Strains and plasmids used in this study

Strains

Streptomyces sp. SS

Wild-type strain (sansanmycin-producing strain), CPCC 200442

[1]

 SS/XKO

Mutant of Streptomyces sp. SS with the in-frame deletion of ssaX

This study

 SS/XKO/pL-ssaX

SS/XKO with the expression vector pL-ssaX, Am^r

This study

 SS/pL-ssaX

Streptomyces sp. SS with the expression vector pL-ssaX, Am^r

This study

Escherichia coli

 DH5α

General cloning host

[39]

 ET12567/pUZ8002

Donor strain for intergeneric conjugation between E. coli and Streptomyces, Cm^r, Km^r

[40]

 BW25113/pIJ790

Strain for RED/ET-mediated recombination, Cm^r

[21]

 ΔtolC mutant

Strain for testing antimicrobial activity

[44]

Pseudomonas aeruginosa 11

Strain for sansanmycin bioassays

[6]

Bacillus subtilis CMCC (B) 63501

Strain for testing antimicrobial activity

Mycobacterium tuberculosis

Strain for testing antimicrobial activity

 H₃₇Rv

Standard strain, susceptible to isoniazid and rifampicin

 FJ05189

Clinically isolated multi-drug-resistant strain, resistant to isoniazid and rifampicin

 FJ05120

Clinically isolated multi-drug-resistant strain, resistant to isoniazid and rifampicin

 FJ05195

Clinically isolated extensive-drug-resistant strain, resistant to isoniazid, rifampicin, ethambutol, streptomycin, kanamycin and ofloxacin

Plasmids

13R-1

Cosmid based on vector pOJ446, containing the majority of sansanmycin biosynthetic gene cluster ssaM–ssaV including ssaX

[11]

13R-1-SCP2KO

Cosmid 13R-1with the minimal replicon of SCP2* replaced by ampicillin resistance marker bla, Amp^r, Am^r

This study

13R-1-SCP2KO-XKO

Cosmid 13R-1-SCP2KO with the in-frame deletion of ssaX, Amp^r, Am^r

This study

pIJ779

Vector used as the template for amplifying aadA cassette, Spec^r

[21]

pSET152

Streptomyces integrative vector, Am^r

[22]

pL646

pSET152 derivative containing the constitutive promoter ermE*p, Am^r

[36]

pL-ssaX

pL646 derivative plasmid containing 843 bp complete coding region of ssaX

This study