Ninety-five streptomycin-nonproducing mutants derived from Streptomyces griseus FT-1 by UV-irradiation could be classified into major two classes by cosynthesis tests. Class I mutants (42 strains) were mutants blocked in the pathway of streptomycin biosynthesis while class II mutants (49 strains) required a factor for streptomycin biosynthesis which was excreted by the parental or class I mutant strains. The factor could be replaced by synthetic A-factor (2S-isocapryloyl-3S-hydroxymethyl-r-butyrolactone) which restored both streptomycin biosynthesis and spore formation in the class II mutants. A-Factor deficient mutants were obtained from several strains of S. griseus and S. bikiniensis at high frequency by treatment with acridine orange or incubation at high temperature.A mutant whose streptomycin biosynthesis was independent of A-factor deficiency was found. The production of A-factor was distributed among various species of actinomycetes.

The bactericidal activity of commonly used antiseptics against clinical isolates was determined. It is noteworthy that povidone-iodine (PVP-I) solution showed high bactericidal activity against all of the test strains after 30 s of exposure. However, in the case of chlorhexidine gluconate (CHG), residual bacteria were observed in most species. Next, acquisition of resistance to antiseptics was examined, and it was found that remarkable increases in MICs were seen for CHG and alkyldiaminoethylglycine hydrochloride. The strains which acquired resistance against one antiseptic showed cross-resistance to all antiseptics except for PVP-I. As for bactericidal activity against biofilm, no viable cells were seen after a 10-min exposure to PVP-I solution. No decrease in viable cell count was seen even after a 60-min exposure to any of the other antiseptics. PVP-I showed high activities in all the tests conducted in this study. Thus, PVP-I was confirmed to be a clinically useful antiseptic.

A-factor is a potent pleiotropic effector produced by Streptomyces griseus and is essential for streptomycin production and spore formation in this organism. Its production is widely distributed among various actinomycetes including Streptomyces coelicolor A3(2). Genetic analysis of A-factor production was carried out with S . coelicolor A3(2), and two closely linked loci for A-factor mutations (afsA and B) were identified between cysD and leuB on the chromosomal linkage map. In contrast, genetic crosses of A-factor-negative mutants of S. griseus, using a protoplast fusion technique, failed to give a fixed locus for A-factor gene(s) and suggested involvement of an extrachromosomal or transposable genetic element in A-factor synthesis in this organism. INTRODUCTIONA-factor, 2-S-isocapryloyl-3-S-hydroxymethyl-y-butyrolactone, found in Streptomyces griseus and Streptomyces bikiniensis (Khokhlov et al., 1973), is a potent autoregulating factor essential for both streptomycin biosynthesis and spore formation in these organisms (Khokhlov et al., 1973;Khokhlov, 1980; Hara & Beppu, 1982a). Furthermore, recent work from this laboratory has revealed that A-factor is also involved in streptomycin resistance in these organisms through its inducible effect on the synthesis of streptomycin-6-phosphotransferase (Hara & Beppu, 1982 b). Mutants lacking A-factor simultaneously lose streptomycin production capability, the ability to form spores and a large degree of streptomycin resistance. Exogenous supplementation of A-factor to the culture of these mutants restores all these phenotypes. A-factor-negative mutants of S . griseus and S. bikiniensis were easily obtained at high frequency by treatment with acridine dyes or by incubation at high temperature, which suggested involvement of an extrachromosomal genetic determinant in the biosynthesis of A-factor in these organisms.A-factor productivity has been found in various species of actinomycetes including Streptomyces coelicolor A3(2) (Efremenkova et al., 1979; Hara & Beppu, 1982a), but in contrast to S . griseus and S. bikiniensis, no A-factor-negative mutants of S. coelicolor A3(2) were obtained by the curing treatments. In this report, we describe genetic analyses of A-factor genes of S . coelicolor A3(2) and S . griseus, using conjugation and protoplast fusion techniques, respectively. The results clearly indicate that A-factor gene(s) of S. coelicofor A3(2) are located at a fixed position on the chromosomal linkage map, while in S . griseus, they appear to be extrachromosomal.t Present address: Fermentation Technology Laboratories, Meiji