Plate-based dormancy culture system for Mycobacterium smegmatis and isolation of metronidazole-resistant mutants.
Mycobacterium smegmatis is an obligate aerobe. However, growth analyses in oxygen-limited liquid cultures have shown that the bacillus is able to survive anoxia with a half-life of 4 days by shifting down to a drug-resistant, dormant state. Metronidazole is the first lead against dormant bacilli and shows selective toxicity for this physiological state. Here, we report a plate-based dormancy culture system employing anoxic jars for M. smegmatis. Its usefulness for the genetic analysis of dormancy was demonstrated by isolating the first metronidazole-resistant mutants. Highly resistant mutants formed slightly yellow (as opposed to creamy) colonies. Furthermore, high-level metronidazole resistance correlated with an increased half-life of 12 days under anoxic conditions. This suggests a link between metronidazole susceptibility and anaerobic survival.
Lim
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A
Institute of Molecular and Cell Biology, 30 Medical Drive, 117609, Singapore, Singapore.
Dick
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T
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003470:Culture Media; D004352:Drug Resistance, Microbial / Q000235:genetics; D008795:Metronidazole / Q000494:pharmacology*; D009154:Mutation; D020102:Mycobacterium smegmatis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D012641:Selection, Genetic
D000900:Anti-Bacterial Agents; D003470:Culture Media; D008795:Metronidazole