Antibacterial activity of human prostasomes

BACKGROUND. Prostasomes are prostate-derived organelles in semen exhibiting pluripotent properties. The present study deals with their possible antiba cterial effects. METHODS. Antibacterial activity was assessed by growth inhibition of bacter ia in an incubation medium containing prostasomes, after which the incubate was inoculated on cystine lactose electrolyte deficient agar (CLED) plates . In cases involving Bacillus megaterium, the effects were also documented ultrastructurally with scanning electron microscopy and atomic force micros copy. RESULTS. A dose-dependent growth inhibition was apparent, and a complete in hibition of growth was seen at a prostasome protein concentration of 30 mu g/ml with Bacillus megaterium. Ultrastructurally, increasingly irregular co ntours and a loosening of the smooth surface were observed, combined with a fragmentation of the bacteria. Among 9 other bacterial strains tested, a c omplete growth inhibition by prostasomes was attained in 3 strains, while t he other 6 were unaffected. CONCLUSIONS. Our data suggest that prostasomes, or prostasome-derived prote ins, are responsible for the antibacterial effects on Bacillus megaterium a nd some other bacterial strains. The results may serve as a basis of develo pment of a new class of antibacterial drugs. (C) 2000 Wiley-Liss, Inc.