Physiological role of germicidins in spore germination and hyphal elongation in Streptomyces coelicolor A3(2)

Four germicidin homologs were isolated from a liquid culture of Streptomyces coelicolor A3(2). These were identified as germicidins A, B and C, and surugapyrone A (germicidin D). Absolute stereochemistry of the chiral center in germicidins A and C is determined to be S. All germicidins inhibited germination of S. coelicolor A3(2) spores above 1 mu g ml(-1). S. coelicolor A3(2) spores collected from a single petri dish (9cm i.d.) contained 5.4 mu g of germicidin A (similar to 2.7 x 10(-14) g per spore), which accounts for 2.3% of the spore extract, and contents of germicidins B, C and D were 0.2-0.8 mu g. The activity of the spore extract corresponded well with the sum of the activity of each germicidin, which was estimated from the content and dose-response curve, which indicates that germicidins functions as self-germination inhibitors in S. coelicolor A3(2). Inhibitory action of germicidin A on spore germination was reversible and germicidin A inhibited not only spore germination but also hyphal elongation. The Journal of Antibiotics (2011) 64, 607-611; doi: 10.1038/ja.2011.59; published online 27 July 2011