Table 5.

Mantel test of relationship of different gene categories to corresponding environmental variables

Gene category	Environmental variable	rM	P
Arsenic resistant genes	Arsenic	0.3243	0.018
Chromium resistant genes	Chromium	0.8295	0.001
Copper resistant genes	Copper	0.5743	0.017
Mercury resistant genes	Mercury	0.8176	0.002
dsr genes	sulfur	0.5172	0.007
dsr genes	all studied metal	0.6927	0.013

The signal intensity of different functional genes among 9 samples was used as the first matrix; normalized related environmental variables were used as the second matrix