The author and his colleague were successful to clone several DNA fragments containing Streptomyces promoters that restored the expression of the mel gene on pIJ702 in Streptomycesjumonjinensis. This article outlines the system available for cloning Streptomyces promoters. One of the cloned promoters was described for its structure in comparison with other known Streptomyces promoters. Construction of wide-host-range vector plasmids (pIJ702 derivatives containing these promoters substituted for the mel gene promoter) was also provided. One of the vectors (pMEL18) was successfully used for cloning a DNA fragment from S. flavovirens, which codes for a hydroxylase catalysing the formation of pravastatin sodium (a new choresterol-lowering drug), into S. lividans.
Streptomyces canus ISP5017 produced a mixture of carotenoids by photoinduction. Biochemical studies on the mechanism of photochromogenicity in Streptomyces canus showed that photochromogenicity consists of a photochemical reaction step and a light-independent metabolic reaction step. In the former step, both light and oxygen were required. In the latter step, de novo protein synthesis was induced, as light exposure at 0-4 °C did not induce carotenoid synthesis in S. canus.
Pathogenic Nocardia species was found to have characteristic drug susceptibility profiles against certain ranges of chemotherapeutic agents, such as imipenem, aminoglycosides and 5-fluorouracil (5-FU). Based on the individual susceptibility patterns (expressed as + for sensitive and - for nonsensitive) to 50 μg/ml of imipenem, tobramycin and 5-FU, clinical isolates of Nocardia are easily and rapidly assignable to N. brasiliensis (−,+,−), N. asteroides (+,+,−), N. farcinica (+,−,−) and N. nova (+,−,+).
Most of papers, by Nonomura and Ohara, on the isolation, taxonomy and ecology of rare actinomycetes from Japanese soil have been cited in detail in books such as The Prokaryotes, Vol. II (Springer-Verlag, 1981), The Biology of the Actinomycetes (Academic Press, 1983) and Bergey’s Manual of Systematic Bacteriology, Vol.4 (Williams & Wilkins, 1989). This article is a memorandum of these papers and of the papers, which recently published by the author and his co-workers, on the isolation methods and ecological factors of soil actinomycetes.
The morphological characteristics of newly isolated actinomycete strains resembled those of Streptomyces strains, but the cell wall of these strains were of a new type containing similar amounts of both LL-DAP and meso-DAP, which is the most important characteristic of these strains. Based on these findings, a new genus Kitasatosporia was proposed for these strains. When strains of this genus were cultivated in liquid media, filamentous mycelia(FM) and submerged spores(SS) were produced. FM contained mostly meso-DAP and SS contained only LL-DAP. When grown on agar media, vegetative mycelia contained meso-DAP and aerial spores (AS) contained LL-DAP. Thus a good correlation between the cell morphology and the types of DAP isomers was demonstrated. The SS and AS were resistant to sonication, but were sensitive to lysozyme digestion and moist heat. The cell walls of SS and AS contained the same amino acids (LL-DAP, alanine, glutamic acid and glycine) in almost identical molar ratios.