Abstract
Plasmid pGC91. 14 harboring the transposonTn951, which codifies forlac operon, was introduced by conjugation inRhodobacter capsulatus. Nevertheless β-galactosidase activity in these strains was so low that they were unable to grow with lactose as the only carbon source. For this reason, chromosomal mutants of theR. capsulatus (pGC91. 14) strain able to grow on lactose minimal medium were isolated by mutagenesis withN-methyl-N′-nitro-N-nitrosoguanidine. In these mutants, the transcription of thelac operon was stimulated by the addition of lactose but not by the analogue isopropyl-β-d-thiogalactopyranoside. Furthermore, and contrary toEscherichia coli cells, addition of either cAMP or glucose to the cultures of the Lac+ mutants ofR. capsulatus (pGC91. 14) did not produce any effect on the expression of β-galactosidase.
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Barbé, J., Garí, E. & Llagostera, M. Regulation oflac operon in lactose-utilizing mutants ofRhodobacter capsulatus . Current Microbiology 16, 185–189 (1988). https://doi.org/10.1007/BF01568527
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DOI: https://doi.org/10.1007/BF01568527