Table 1.

selectable markers for Borrelia

ANTIBIOTIC RESISTANCE CASSETTES
gene	promoter	origin	resistance	selection (μg ml−1)	comments	reference
gyrB301	Native (gyrB)	B. burgdorferi chromosome	coumermycinA1	0.2–5	high rate of recombination at endogenous gyrB locus; pleiotropic effects	(Samuels et al., 1994)
aphl	flgB, flaB	E. coli Tn903	kanamycin	200–400	first widely used selectable marker in Borrelia	(Bono et al., 2000; Battisti et al., 2006)
ermC	native	Staphylococcus aureus	erythromycin	0.03–0.06	some Borrelia strains are resistant to erythromycin	(Sartakova et al., 2000)
aacC1	flgB, flaB	Pseudomonas aeruginosa Tn1696	gentamicin	40	selection with this marker can be variable in E coli	(Elias et al., 2003)
aadA	flgB, flaB	Shigella flexneri plasmid R100	streptomycina	50	aconfers resistance to both streptomycin and spectinomycin	(Frank et al., 2003; Jewett et al., 2007a)
bsdBb	flgB	Aspergillus terreus	blasticidin	10–160	codon-optimized for Borrelia	(Takacs et al., 2018)
hphBb	flgB	E. coli	hygromycin	0.2–0.3	codon-optimized for Borrelia	(Takacs et al., 2018)

^aStreptomycin is used for selection in B. burgdorferi because spontaneous resistance to spectinomycin is high, whereas spectinomycin is used in E coli, because many strains are resistant to streptomycin.