¹ H- and ¹³ C-NMR spectra were taken on a Bruker DMX 600 NMR spectrometer using TMS as an internal standard. FAB mass spectra were recorded on a Krapos mass spectrometer using m -nitrobenzyl alcolhol as a matrix. The first seed-culture of the organism, prepared by incubation at 30 ^o C for 2 days on a reciprocal shaker (180 rpm) in Tryptic Soy Broth (TBS, Sigma, 50 mL) was inoculated into the same medium and cultured under the same culture condition for the second seed-culture. The production culture medium (20 liters) was chosen among the three media ( 4 ), which was cultured on a jar fermentor for 4 days at 30 ^o C with an air flow of 2−3 liters per minute and agitation rate of 175 rpm. The harvested cells were extracted with MeOH, and the extract was chromatographed on a column packed with silica gel which was eluted with CH ₂ Cl ₂ −MeOH (30:1, v/v) to give a mixture of four macrolactone class of compounds 1−4 . Each of the components was finally purified by reverse-phase HPLC (Inertsil ODS-2, 5 μm, i.d. 4.6×150 mm: solvent system: CH ₃ CN−H ₂ O = 1:1 (v/v): detection: UV at 275 nm).