Mechanism of natural rifampin resistance of Streptomyces spp.
In a previous phylogenetic study of the genus Streptomyces using the rpoB gene, N531, which stands for an aspargine residue in position 531 of RpoB instead of serine (S531), known to be associated with natural rifampin resistance in several organisms, was also observed in the RpoB of several Streptomyces species. To determine whether N531 is associated with the rifampin resistance of Streptomyces strains, we analyzed the rifampin minimum inhibitory concentrations (MICs) of 11 strains of the N531 RpoB type (putative rifampin resistant strains) and of 12 strains of the S531 RpoB type. (putative rifampin susceptible strains). In general, the N531 RpoB types showed higher MIC levels (16-128 microg/ml) than the S531 RpoB types (0-8 microg/ml). To determine the isolation frequencies of N531 RpoB types versus rifampin concentration, we applied screening methods involving different rifampin concentrations (0, 20 and 100 microg/ml) to Korean soils. Higher isolation frequencies of the N531 RpoB types were observed at the higher rifampin concentrations. In addition, during the course of this study we developed an allele specific PCR method to detect rifampin resistant Streptomyces strains. Our results strongly suggested that N531 might be involved in a major mechanism of natural rifampin resistance in strains of the genus Streptomyces.
Kim
Hong
H
Department of Microbiology, College of Medicine, Seoul National University, 28 Yongon-dong, Chongno-gu, Seoul 110-799, Republic of Korea.
Kim
Sun-Hyun
SH
Ying
Yuan-Hai
YH
Kim
Hyun-Ju
HJ
Koh
Young-Hwan
YH
Kim
Chang-Jin
CJ
Lee
Sueng-Hyun
SH
Cha
Chang-Yong
CY
Kook
Yoon-Hoh
YH
Kim
Bum-Joon
BJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D012321:DNA-Directed RNA Polymerases / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D012293:Rifampin / Q000494:pharmacology*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013302:Streptomyces / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification
D004791:Enzyme Inhibitors; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit; D012293:Rifampin