Growth abnormalities in microorganisms exposed to tobacco leaf extracts

Abstract

Unusual cultural changes were observed when several bacterial and yeast strains were grown on a medium containing aqueous extracts of tobacco leaves. In 24–48 h incubation on such a medium, several dark-brown papilla-like structures developed on the surface of normally smooth colonies. Moreover, smaller dark-brown refractile globular bodies were observed in the medium in areas beneath and surrounding the microbial colonies with papilla-like structures. Attempts to demonstrate the viability of these globular bodies failed. The cultural abnormalities observed on tobacco extract medium were unique to this medium since they were not detected in a wide variety of culture media tested. The lowest concentration of tobacco extract (dry wt. basis), which is required for the development of this phenomenon, was determined to be 0.5 mg/ml of medium.