TABLE 3.

Inhibitory effects of different concentrations of cheese, feces, and meat on the amplification capacities of nine thermostable DNA polymerases

DNA polymerase	Sampleb	PCR resultsa with sample concn of:
		20%	2%	0.2%	0.1%	0.07%	0.05%	0.04%
AmpliTaq Gold	Cheese	−+	++	++	++	++	++	++
	Feces	−−	−−	++	++	++	++	++
	Meat	−−	−−	−−	−+	−+	++	++
Expand High Fidelity	Cheese	++	++	++	++	++	++	++
	Feces	−−	−−	++	++	++	++	++
	Meat	−−	−−	±+	++	++	++	++
HotTub	Cheese	±+	++	++	++	++	++	++
	Feces	−−	−−	−−	++	++	++	++
	Meat	−−	−−	−−	±+	±+	++	++
Pwo	Cheese	±+	++	++	++	++	++	++
	Feces	−−	−+	++	++	++	++	++
	Meat	−−	−−	−−	++	++	++	++
rTth	Cheese	±+	++	++	++	++	++	++
	Feces	−−	−−	++	++	++	++	++
	Meat	−−	−−	−±	++	++	++	++
Taq	Cheese	±+	++	++	++	++	++	++
	Feces	−−	−−	−−	±+	++	++	++
	Meat	−−	−−	−−	±+	++	++	++
Tfl	Cheese	++	++	++	++	++	++	++
	Feces	−−	−−	−−	−±	++	++	++
	Meat	−−	−−	−±	−+	++	++	++
Tli	Cheese	++	++	++	++	++	++	++
	Feces	−−	−−	−−	−−	−+	++	++
	Meat	−−	−−	−−	±+	++	++	++
Ultma	Cheese	−−	−−	++	++	++	++	++
	Feces	−−	−−	−−	−±	−+	++	++
	Meat	−−	−−	−−	−−	−−	−−	−−

^aTwo independent PCR results. Symbols: +, band of good intensity; ±, band of low intensity; −, no band. 

^bPercentage (vol/vol) of homogenates of cheese, feces, and meat in the PCR mixtures containing 1 ng of L. monocytogenes DNA.