TABLE 1 .

Performance of the random forest model for predicting environmental contamination by uranium or nitrate in 69 wells at the OR-IFRC site using microbial functional genes as predictors

Contaminant	Predictora	OOB error rate (%)	No. of wells predicted/no. of wells defined
			Background wellsb	Contaminated wellsc
Uranium	All S cycling and metal-related genes	28.99	47/47	2/22
	All dsrA, cytochrome, and hydrogenase genes	24.64	47/47	5/22
	All dsrA genes	24.64	47/47	5/22
	All cytochrome genes	26.09	46/47	5/22
	All hydrogenase genes	28.99	41/47	8/22
	Key dsrA, cytochrome, and hydrogenase genes	27.54	45/47	5/22
	Key dsrA genes	24.64	45/47	7/22
	Key cytochrome genes	39.13	38/47	4/22
	Key hydrogenase genes	42.03	33/47	7/22
	AUC-RF selection	11.59	47/47	14/22
Nitrate	All N cycling genes	36.23	39/44	5/25
	All nifH, amoA, narG, nasA, and napA genes	34.78	40/44	5/25
	All nifH genes	33.33	41/44	5/25
	All amoA genes	27.54	41/44	9/25
	All narG genes	36.23	40/44	4/25
	All nasA genes	36.23	37/44	7/25
	All napA genes	34.78	41/44	4/25
	Key nifH, amoA, narG, nasA, and napA genes	30.43	40/44	8/25
	Key nifH genes	27.54	41/44	9/25
	Key amoA genes	28.99	39/44	10/25
	Key narG genes	37.68	37/44	6/25
	Key nasA genes	40.58	32/44	9/25
	Key napA genes	40.58	32/44	9/25
	AUC-RF selection	15.94	42/44	16/25

^aKey functional genes detected from each family are listed in Tables S3 and S4 in the supplemental material.

^bIn background wells, the concentrations of uranium or nitrate were 30 µg/liter or below or 10 mg/liter or below, respectively.

^cIn contaminated wells, the concentrations of uranium or nitrate were higher than 30 µg/liter or 10 mg/liter, respectively.