Antibacterial activity of human prostasomes

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Abstract
BACKGROUND Prostasomes are prostate-derived organelles in semen exhibiting pluripotent properties. The present study deals with their possible antibacterial effects. METHODS Antibacterial activity was assessed by growth inhibition of bacteria 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 microscopy. RESULTS A dose-dependent growth inhibition was apparent, and a complete inhibition of growth was seen at a prostasome protein concentration of 30 μg/ml with Bacillus megaterium. Ultrastructurally, increasingly irregular contours and a loosening of the smooth surface were observed, combined with a fragmentation of the bacteria. Among 9 other bacterial strains tested, a complete growth inhibition by prostasomes was attained in 3 strains, while the other 6 were unaffected. CONCLUSIONS Our data suggest that prostasomes, or prostasome-derived proteins, are responsible for the antibacterial effects on Bacillus megaterium and some other bacterial strains. The results may serve as a basis of development of a new class of antibacterial drugs. Prostate 44:279–286, 2000.