title: Evidence for incorporation of thymidine into deoxyribonucleic acid in airborne bacterial cells.
abstract: As part of an effort to discover whether bacteria might propagate within airborne particles, we studied the incorporation of thymidine into the trichloroacetic acid-insoluble fraction of airborne cells of Serratia marcescens to seek evidence of the possible formation of new DNA. Two aerosols, one of S. marcescens and another of [3H]thymidine ([3H]dT) suspended in growth medium were caused to aggregate in air just prior to directing the aerosols into rotating-drum aerosol storage chambers. The age of the S. marcescens culture and other conditions for maximizing ([3H]dT) uptake were selected on the basis of prior in vitro trials. With 10-h cultures and addition of 2-deoxyadenosine to the [3H]dT, we showed that [3H]dT is incorporated into the trichloroacetic acid-insoluble fraction of cells recovered 6 h after aerosols were stored under the conditions of high humidity and 30 degrees C. Tests conducted in the same manner with Formalin-killed S. marcescens ruled out the possibility of adsorptive carry-over of [3H]dT. As much as 20 times more activity was found in the trichloroacetic acid-insoluble fraction of live cells than of dead cells.
mesh_terms: D000336:Aerosols; D000391:Air Microbiology; D002455:Cell Division; D004269:DNA, Bacterial / Q000096:biosynthesis*; D005557:Formaldehyde / Q000494:pharmacology; D012706:Serratia marcescens / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism*
chemical_list: D000336:Aerosols; D004269:DNA, Bacterial; D005557:Formaldehyde; D013936:Thymidine