Abstract

Bacillus macerans Schardinger appeared on culture media and forceps used in serial transfers of Ulmus americana callus tissue after several contamination-free transfers and may have originated as an endophyte in the leaf tissue used as an explant. Bacteria remained viable on forceps stored for several weeks in 95% ethanol whether or not the excess was burned off in a flame from an alcohol lamp. Bacteria were eliminated from forceps treated similarily with 85% ethanol. The bacterium on artificially contaminated forceps remained viable after immersion up to 4 hr in either 95%, 85%, 80%, or 70% ethanol with or without flaming. Artificial contamination was eliminated, either by autoclaving for 20 min at 121C (185.8F) or exposure to a bunsen burner flame for 6-8 sec. Bacillus macerans remained viable in both naturally and artificially contaminated ethanol at dilutions of 95%, 85%, 80%, and 70%. Thus, forceps may be contaminated by latent bacteria in callus or contaminated ethanol. Ethanol may become contaminated by storage of nonsterile forceps and airborne spores introduced during routine, septic procedures.