Table 2.

DNA yield, A_260/280 ratio, A_260/230 ratio, number of 16S rRNA amplicon sequencing reads, and 16S rRNA gene copies/g from each soil DNA extraction method.

	Sample ID	DNA Yield (ng/µL)	A260/280 *	A260/230 *	Method	Number of Reads	16S rRNA Gene Copies/g
	FM-1	1.8	1.74	0.23	Normal	0	0
	FM-2	1.8	1.11	0.33	Normal	0	0
	FM-3	3.2	1.2	0.17	Normal	0	0
	FM-B1	68.8	1.55	0.4	Beating	0	0
	FM-B2	12.5	1.61	0.18	Beating	0	0
	FM-B3	68.8	1.55	0.4	Beating	0	0
	FM-H1	0.5	1.91	0.05	Heating	0	0
	FM-H2	1.6	1.21	0.08	Heating	0	0
PowerSoil	FM-H3	1.2	1.56	0.01	Heating	0	0
	FM-CER1	5	0.75	0.03	CER	0	0
	FM-CER2	2.4	2.25	0.02	CER	0	0
	FM-CER3	6	0.87	0.06	CER	0	0
	FM-P1	9	1.62	0.03	PBS	0	0
	FM-P2	13	1.89	0.13	PBS	0	0
	FM-P3	9	3.15	0.03	PBS	0	0
	FM-PC1	5	5.31	0.04	PBS+CER	0	0
	FM-PC2	9	1.28	0.01	PBS+CER	0	0
	FM-PC3	19	1.39	0.01	PBS+CER	0	0
	FM-N1	1.3	1.59	0.04	N2	0	0
	FM-N2	1.1	1.93	0.03	N2	0	0
	FM-N3	3.2	1.47	0.08	N2	0	0
	FM-MP1	9.144	2.47	0.01	Normal	28,642	30,380
MP	FM-MP2	9.331	2.7	0.01	Normal	29,743	38,550
	FM-MP3	8.391	2.62	0.01	Normal	37,805	42,070

* A_260/280, the ratio of absorbance at 260 nm and 280 nm is used to assess the purity of DNA. A₂₆₀: DNA absorbs with a peak at 260 nm. A₂₈₀: protein absorbs with a peak at 280 nm. A_260/230: the ratio of absorbance at 260 nm and 230 nm is used as a secondary measure of DNA purity. A_260/280 around 1.8 and A_260/230 in the range of 2.0–2.1 means the DNA is generally accepted as “pure”.