The actinomycete strain LS-A24 active against some plant fungal and oomycete pathogens wasisolated from a soil sample of the Sunghwan Lake in Korea. The cell wall composition and sporeshape of strain LS-A24 were
LL-diaminopimelic acid and spiral type, respectively. On the basis of thephysiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, strainLS-A24 was identical to
Streptomyces roseoflavus. An antifungal and antioomycete antibiotic wasisolated from LS-A24 using various chromatographic procedures. The molecular formular of theantibiotic was determined to be C
28H
26N
4O
3, and on the basis of the NMR data, the antibiotic wasconfirmed to be staurosporine, 2,3,10,11,12,13-hexahydro-10
R-methoxy-9
S-methyl-11
R-methylamino-9
S,13
R-epoxy-1H,9H-diindolo[1,2,3-gh:3',2',1'-lm]pyrrolo[3,4-j][1,7]benzodiazonin-1-one. Staurosporine completely inhibited the mycelial growth of
Colletotrichum orbiculare,
Phytophthora capsici,
Rhizoctonia solani,
Botrytis cinerea, and
Cladosporium cucumerinum with minimum inhibitoryconcentration (MIC) values of 1-50
g/mL for MICs. Staurosporine also was active against
Saccharomyces cerevisiae,
Bacillus subtilis ssp
. subtilis, and
Xanthomonas vesicatoria. Staurosporineand the commercial fungicide metalaxyl inhibited the development of
Phytophthora blight on pepperplants. However, the control efficacy of staurosporine against the
Phytophthora disease was somewhatless than that of metalaxyl. This is the first study to isolate staurosporine from
S. roseoflavus anddemonstrate its in vitro and in vivo antioomycete activity against
P. capsici.Keywords:
Streptomyces roseoflavus; staurosporine; antifungal activity; antioomycete activity;
Phytophthora blight