The Use of Ethanol for the Selective Isolation of Bacillus Strains Originating from Spores

The use of ethanol as selective agent for the isolation of Bacillus cultures was studied. Ethanol at 10% prevents the growth of 28 different Bacillus strains. 10 out of the 28 strains were already inhibited using ethanol concentration of 5%. All the strains were found able to grow in media containing 2% ethanol. The vegetative cells of B. polymyxa were killed in less than 5 min after exposure to 50% ethanol whereas they were killed after 10 min exposure to 25% ethanol. B. cereus was killed after 5 min by 50% ethanol and after 30-60 min by a concentration of 25% ethanol. After 30 min the vegetative cells of B. subtilis were totally killed by 50% ethanol. Ethanol concentrations of 25-75% were ineffective against Bacillus spores , even with prolonged exposure up to 24 h. Germination percent of the spores decreased gradually with increasing ethanol concentrations in the growth medium.