Composition and toxicity of diethyl ether soluble lipids from Nocardia asteroides GUH-2 and Nocardia asteroides 10905

Virulent Nocardia asteroides GUH-2 and avirulent N. asteroides 10905 contained 8.2% and 10.6% of diethyl ether soluble lipids (DESL) per dry cell mass, respectively. Intraperitoneal (i.p.) inoculation of 250 micrograms of DESL from GUH-2 dissolved in mineral oil was toxic to mice, resulting in weight loss and death of 100% of the animals (20/20) within 20 days. In contrast, DESL from 10905 had very little toxicity, and only one mouse (1/10) died within 30 days. Three fractions resulted from DESL by silicic acid column chromatography: (1) neutral lipids and fatty acids (NFA); (2) glycolipids (GL); and (3) phospholipids (PL). Each fraction dissolved in mineral oil was inoculated into mice as described above. The NFA and PL were not toxic. GL from 10905 had low toxicity (30% of the animals died, 3/10) whereas GL from GUH-2 expressed high toxicity (100% of the animals became cachetic and died, 10/10). GL from 10905 represented a minor component (0.6% of dry cell weight) whereas GL from GUH-2 was more prominent (1.5% of dry cell wt.). Approximately 95% of GL from GUH-2 had properties of an authentic trehalose-6,6'-dimycolate standard. Infrared spectrum of the major glycolipid (GUH-2 GL) had characteristic absorptions in the fingerprint region between 800 cm-1 and 1500 cm-1. Upon alkaline hydrolysis GUH-2 GL released 76% mycolic acids in the C50 size range plus 24% trehalose.(ABSTRACT TRUNCATED AT 250 WORDS)