were used as conjugative vectors. E. coli ET12567 derivatives were maintained in Luria–Bertani
broth (LB) supplemented with apramycin (50 lg ml)1
),
chloramphenicol (25 lg ml)1
) and kanamycin (25 lg
ml)1
) as required. S. rimosus strains R7 (ATCC10970),
M4018 and R6-593 (gifted from I.S. Hunter and
D. Hranueli) were used as recipients and were grown on
mannitol soya agar (MS; Hobbs et al. 1989) for preparation
of spores and in tryptone soya broth (TSB; HiMedia,
India) for preparation of mycelia. MS, ISP 4 (Shirling
and Gottlieb 1966) and tryptone soya agar (TSA; Oxoid
CM0131, UK) containing 10 m mol l)1 MgCl2 were used
as conjugative media.