%0 Journal Article %A Harper, G. J. %A Morton, J. D. %T Bacillus subtilis Spores labelled with Radiophosphorus %D 1952 %J Microbiology, %V 7 %N 1-2 %P 98-106 %@ 1465-2080 %R https://doi.org/10.1099/00221287-7-1-2-98 %I Microbiology Society, %X Summary: Bacillus subtilis was grown in surface culture on media containing about 0·6 mC./ml. of 32P as phosphate, and harvested after 2 days. The spore suspension was heated at 60° for 1½ hr. and washed by centrifuging and resuspending in water six times. The fresh suspension contained about 2 × 109 spores/ml., of which 20 % were viable. The radioactivity was about 0°05 mC./ml. of which more than 95 % was carried by the spores. The radioactivity was sufficient for 103 spores to be readily detected and assessed by conventional Geiger-Müller counting methods. These highly radioactive suspensions are particularly useful in studying the respiratory retention of bacterial aerosols. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-7-1-2-98