Generation of useful insertionally blocked sterol degradation pathway mutants of fast-growing mycobacteria and cloning, characterization, and expression of the terminal oxygenase of the 3-ketosteroid 9[alpha]-hydroxylase in Mycobacterium smegmatis [mc.sup.2]155

Article Abstract:

Integration of the pCG79 temperature sensitive plasmid carrying Tn611 was used to generate libraries of mutants with blocked sterol-transforming ability of the sterol-utilizing strains Mycobacterium smegmatis [mc.sup.2]155 and Mycobacterium phlei M51-Ept. A blocked 4-androstene-3,17-dione producing M. phlie mutant transformed sitosterol to 23, 24 dinocholane derivatives and the open reading frame encodes the 383-amino acid terminal oxygenase of 3-ketosteroid 9[alpha]-hydroxylase in M. smegmatis [mc.sup.2]155.

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Ability of Shiga toxin-producing Escherichia coli and Salmonella spp. to survive in a desiccation model system in dry foods

Article Abstract:

The survival of 58 diarrheagenic strains and of 15 nonpathogenic Escherichia coli strains are determined after drying at 35 degree Celsius for 24 h in paper disks to determine desiccation tolerances of bacterial strains. The effects of pH, food ingredients such as sucrose, storage period, and storage temperature are examined and the survival of these desiccated bacteria in selected dry foods after artificial inoculation are studied.

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Reactivation of insertionally inactivated Shiga toxin 2 genes of Escherichia coli O157:H7 caused by nonreplicative transposition of the insertion sequence

Article Abstract:

An inactivated version of the Shiga toxin 2 genes could revert to the wild type gene if the IS1203v insertion sequence is removed. This insertion sequence is found in STEC strains of E. coli O157:H7.

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