Table 1.

A summary of the estimated values for the biopolymer brush thickness (nm), biopolymer grafting density (μm²) and cellular elasticity (MPa) for the untreated cells (NT) and for cells treated with ampicillin for 3 or 8 h at MICs. The quality of the Hertz or steric models fit the data is provided using the r² mean values.

Strain ID	MIC (μg/ml)	TE (hrs)	n	aSteric Model Results			bHertz Model Results
				L0 (nm)	Γ (μm−2)	r2	E (MPa)	δ(nm)	r2
D4	45	3	37	612 ± 290*	8886 ± 3511*	0.97	0.09 ± 0.03*	151 ± 32*	0.97
	45	8	44	169 ± 64*	18505 ± 5569*	0.97	0.26 ± 0.09*	127 ± 29*	0.98
	NT	5	43	200 ± 39	13840 ± 1726	1.00	0.13 ± 0.04	138 ± 28	0.98
A9	45	3	32	403 ± 95*	29496 ± 7880*	0.95	0.10 ± 0.05*	221 ± 41*	0.97
	45	8	32	267 ± 51*	14519 ± 2001*	0.91	0.14 ± 0.04**	144 ± 45**	0.97
	NT	5	26	286 ± 140	11035 ± 1670	1.00	0.13 ± 0.05	147 ± 48	0.98
A5	50	3	33	204 ± 77	13890 ± 2274	0.99	0.19 ± 0.05	113 ± 28*	0.98
	NT	5	44	215 ± 50	14056 ± 2092	0.99	0.18 ± 0.05	134 ± 39	0.97
H5	50	3	40	385 ± 14*	10602 ± 3000*	1.00	0.43 ± 0.13	88 ± 20*	0.98
	NT	5	39	128 ± 81	22637 ± 5487	1.00	0.37 ± 0.10	113 ± 25	0.98

^*Values are statistically significant (99% confidence) from both the untreated (negative control) and the treatment group.

^**Values are statistically significant (99% confidence) from the treatment group but not from the negative control, p < 0.001. The values are the means ± standard deviations of average measurements performed on 26 to 44 cells obtained from three independent cultures. NT means cells grown in LB without ampicillin supplementation, TE represents the time of exposure (hours), E (MPa) represents the average estimated cellular elasticity, δ(nm) is the indentation distance corresponding to 1 nN indentation force, n is the number of individual cells probed in each condition, L₀ (nm) and Γ (μm⁻²) represent the thickness and the grafting density of the bacterial surface biopolymer brush layer estimated from the steric model, respectively.