Zinc Oxide Nanoparticles Enhance the Tolerance and Remediation Potential of Bacillus spp. against Heavy Metal Stress

Table 4

Effect of different concentrations of ZnO nanoparticles (0, 5, 10, 15, 20, and 25 ppm) on zone of inhibition of Bacillus cereus and Lysinibacillus macroides under heavy metal (Pb, Cd, Cr, and Cu) stress.

Treatments (mg/L)	Zone inhibition assay (mm)
	Control (+)	Lead	Chromium	Cadmium	Copper
Bacillus cereus
Control (HMs) (-)		^ab	^ab	^ab	^bc
5 mg/plate	^bc	^ab	^a	^a	^c
10 mg/plate	^ab	^a	^ab	^ab	^a
15 mg/plate	^a	^ab	^ab	^ab	^ab
20 mg/plate	^ab	^abc	^a	^b	^ab
25 mg/plate	^ab	^d	^a	^a	^bc
Lysinibacillus macroides
Control (HMs) (-)		^b	^d	^b	^b
5 mg/plate	^bc	^b	^b	^b	^b
10 mg/plate	^ab	^b	^b	^b	^d
15 mg/plate	^ab	^e	^c	^e	^g
20 mg/plate	^ab	^b	^e	^e	^b
25 mg/plate	^ab	^c	^f	^d	^f

Values are of three replicates () followed by different alphabetic letters which showed statistically significant at 5% probability level (ANOVA and Duncan’s multiple range test.