We report here that Streptomyces coelicolor A3(2) produces at least se
ven butyrolactone autoregulators: two of the IM-2 type, four virginiae
butanolide type, and one A-factor type. The most abundant one corresp
onds to virginiae butanolide-C-9 having a C2 side chain of nine carbon
s. Model butyrolactone compounds as well as extracts of S. coelicolor
mycelia showed clear induction of morphological differentiation, imply
ing that S. coelicolor A3(2) probably possessed butyrolactone-type aut
oregulator(s) controlling the morphological differentiation.