Table 3.

Influence of metals on the population density of studied microorganisms at maximum growth stage under periodic cultivation conditions.

Metal salt	Microbial strain	Optical density of the population at stationary growth phase
		OD control	OD experience	Percentage difference
Pb	B. clausii	0.160 ± 0.001	0.327 ± 0.001∗∗∗	51.07
	B. licheniformis	0.160 ± 0.002	0.298 ± 0.003∗∗∗	46.31
	B. subtilis	0.161 ± 0.004	0.266 ± 0.002∗∗∗	39.47
Co	B. clausii	0.160 ± 0.001	0.297 ± 0.002∗∗∗	46.13
	B. licheniformis	0.160 ± 0.002	0.282 ± 0.003∗∗∗	43.26
	B. subtilis	0.161 ± 0.004	0.198 ± 0.003∗∗	18.69
Zn	B. clausii	0.160 ± 0.001	0.232 ± 0.003∗∗∗	31.04
	B. licheniformis	0.160 ± 0.002	0.216 ± 0.001∗∗∗	25.93
	B. subtilis	0.161 ± 0.004	0.283 ± 0.006∗∗∗	43.11
Cd	B. clausii	0.160 ± 0.001	0.259 ± 0.003∗∗∗	38.22
	B. licheniformis	0.160 ± 0.002	0.073 ± 0.001∗∗∗	54.38
	B. subtilis	0.161 ± 0.004	0.197 ± 0.005∗∗	18.27

⁣^∗∗p < 0.01; ⁣^∗∗∗p < 0.001.