Development of a novel heterologous β-lactam-specific whole-cell biosensor in Bacillus subtilis

Table 2 Antibiotic compounds, inhibitory concentrations and concentrations tested

Compound	β-Lactam class	Inhibitory conc. in liquid [μg/ml]		Inducing conc. in liquid [μg/ml]^a		Conc. used for DDA [μg/ml]^b
Compound	β-Lactam class	wt	ΔpenP	wt	ΔpenP	wt and ΔpenP
Ampicillin	Penicillins	50	0.04	1	0.02	50
Carbenicillin	Penicillins	12.5	0.09	3	0.01	100
Penicillin G	Penicillins	500	0.04	7.5	0.009	50
Cefalexin	Cephalosporins	0.1	0.09	0.025	0.025	10
Cefoxitin	Cephalosporins	0.8	0.8	0.3	0.3	200
Cefoperazone	Cephalosporins	1.5	1.5	0.5	0.2	200
Cephalosporin C	Cephalosporins	0.01	0.03	0.27	0.27	500
Cefotaxime	Cephalosporins	0.004	0.01	0.037	0.037	200
Aztreonam	Monobactams	500	500	8.3	8.3	2000
Meropenem	Carbapenems	2.5·10⁻⁶	7.6·10⁻⁶	0.016	0.016	10
Bacitracin	–	250	250	40	40	20,000

^aConcentrations tested in the assessment of biosensor activity in liquid culture. Note that two different concentrations have been used due to the higher susceptibility of the penP mutant
^bConcentrations tested in disk diffusion assays (DDA) on solid MH agar plates. Here, the values correspond to the concentration of which 10 μl were applied to the disks

ISSN: 1754-1611