We exploited the natural histidine auxotrophy of Francisella species to develop hisD (encodes histidinol dehydrogenase) as a positive selection marker. A shuttle plasmid (pBR103) carrying Escherichia coli hisD and designed for cloning of PCR fragments replicated in both attenuated and highly virulent Francisella strains. During this work, we formulated a simplified defined growth medium for Francisella novicida.
Elizabeth Ramage, Larry Gallagher, Colin Manoil. Exploiting a natural auxotrophy for genetic selection. Applied and environmental microbiology. 2012 Aug;78(16):5926-8
PMID: 22660718
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