TABLE 1.

Comparison of sample preparation methods for DNA extraction and PCR^a

Method	Sonication time (min)	No. of spores (range) detected by PCR
Autoclaving only (121°C, 20 min)	None	10 3-10 6
Sonication only	0	10 4-10 5
	10	10 4-10 5
	30	10 0-10 4
	60	10 2-10 4
Sonication followed by autoclaving	0	10 2-10 6
	10	10 0-10 4
	30	10 1-10 5
	60	10 0-10 3
Autoclaving followed by sonication	0	10 3-10 5
	10	10 1-10 5
	30	10 3-10 6
	60	10 2-10 6
Germination at 80°C for 2 min, followed by sonication and autoclaving	0	10 0-10 2
	30	10 0-10 1
	60	10 0-10 2
Germination at 80°C for 2 min, followed by autoclaving and sonication	0	10 0-10 2
	30	10 0-10 3
	60	10 0-10 3
Germination at 80°C for 10 min, followed by sonication and autoclaving	0	10 0-10 4
	30	10 0-10 3
	60	10 0-10 3
Germination at 80°C for 10 min, followed by autoclaving and sonication	0	10 0-10 4
	30	10 0-10 3
	60	10 0-10 6
Germination at 60°C for 10 min, followed by sonication and autoclaving	0	10 0-10 5
	30	10 0-10 5
	60	10 0-10 5
Germination at 60°C for 10 min, followed by autoclaving and sonication	0	10 0-10 4
	30	10 0-10 4
	60	10 0-10 5

^aEach protocol was tested with 20 to 30 sets of a series of dilutions, and the DNA in each dilution tube was tested in triplicate.