Table 3.

Genetic mobility via different mechanisms in Salmonella spp.

	Accession	DNA transferred	HGT mechanism	Transfer frequency (TE/donor CFU)a	Source for transfer frequency data	Cargo capacity rateb	Relative frequency of genetic mobilityc
Mobilome component
Plasmids
pSLT	CP001362	Plasmid	Conjugation	4.20 × 10−6 to 2.90 × 10-4	50	0.53 (54/102)	2.22 × 10−6 to 1.54 × 10−4
pS3		Plasmid	Conjugation	1.30 × 10−7	51	0.63 (52/82)	8.24 × 10−8
pOU1114	DQ115387	Plasmid	Conjugation	4.30 × 10−2	52	0.57 (27/47)	2.47 × 10−2
pESI		Plasmid	Conjugation	4.00 × 10−6	53	ND	ND
pWW012	CP022169	Plasmid	Conjugation	1.20 × 10−6	54	ND	ND
Phage
P22		Phage	Lysogenisation	1.57	This work	0.07 (5/70)	1.12 × 10−1
Transposable elements—ICEs
ICESb1	FN298494.1	Conjugative Tn	Conjugation	1.10 × 10−6	55	0.77 (81/105)	8.49 × 10−7
SGI3		Conjugative Tn	Conjugation	1.20 × 10−7 to 1.30 × 10−4	56	0.66 (57/86)	7.95 × 10−8 to 8.62 × 10−5
Chromosomal transfer
Generalised transduction
tetA marker HF1d	AE006468.2	Chromosomal DNA	P22-mediated GT	1.52 × 10−4	17	1.00 (41/41)e	1.52 × 10−4
tetA marker HF2		Chromosomal DNA	P22-mediated GT	1.64 × 10−4	17	1.00 (33.5/33.5)	1.64 × 10−4
tetA marker HF3		Chromosomal DNA	P22-mediated GT	3.07 × 10−4	17	1.00 (44/44)	3.07 × 10−4
tetA marker HF4		Chromosomal DNA	P22-mediated GT	3.00 × 10−4	17	1.00 (37/37)	3.00 × 10−4
tetA marker HF5		Chromosomal DNA	P22-mediated GT	3.13 × 10−5	17	1.00 (42/42)	3.13 × 10−5
tetA marker HF6		Chromosomal DNA	P22-mediated GT	2.00 × 10−5	17	1.00 (43/43)	2.00 × 10−5
tetA marker HF7		Chromosomal DNA	P22-mediated GT	1.93 × 10−5	17	1.00 (43/43)	1.93 × 10−5
Lateral transduction
tetA marker HF1	AE006468.2	Chromosomal DNA	P22-mediated LT	2.33 × 10−3	17	0.51 (21.5/42.5)	1.18 × 10−3
tetA marker HF2		Chromosomal DNA	P22-mediated LT	9.27 × 10−3	17	1.00 (33.5/33.5)	9.27 × 10−3
tetA marker HF3		Chromosomal DNA	P22-mediated LT	6.83 × 10−4	17	1.00 (44/44)	6.83 × 10−4
tetA marker HF4		Chromosomal DNA	P22-mediated LT	2.40 × 10−3	17	1.00 (37/37)	2.40 × 10−3
tetA marker HF5		Chromosomal DNA	P22-mediated LT	1.33 × 10−3	17	1.00 (42/42)	1.33 × 10−3
tetA marker HF6		Chromosomal DNA	P22-mediated LT	4.97 × 10−4	17	1.00 (43/43)	4.97 × 10−4
tetA marker HF7		Chromosomal DNA	P22-mediated LT	9.87 × 10−5	17	1.00 (43/43)	9.87 × 10−5

ND not determined.

Source data are provided as a Source Data file.

^aIn order to enable comparisons between conjugation and the other modes of horizontal gene transfer, transfer frequency of phage-mediated DNA transfer was analysed as transfer events (TE) per bacterial donor cell at the time of prophage induction: TE per donor cell = Transductant Units (TrU) per ml/1.0 × 10⁸ CFU per ml. TrU per ml data was obtained from the sources indicated. Lysogens were induced at OD₆₀₀ 0.2, which is equivalent to 1.0 × 10⁸ CFU per ml in the donor population.

^bCargo capacity rate = Number of accessory ORFs utilisable by the host cell (e.g., virulence factors, AMR genes and HPs)/total ORFs contained within the mobilised DNA sequence. Bracketed values indicate the number of accessories ORFs/total ORFs for each element where sequence data was available for analysis. Phage P22 is proposed to carry five ORFs with lysogenic conversion effects: sieAB and gtrABC.

^cRelative frequency of genetic mobility = transfer frequency × cargo capacity rate.

^dHF, phage headful (43.8 kb); numbers denote the distance of each tetracycline-resistance marker from the phage chromosomal attachment site in terms of headful units in the direction of phage packaging.

^eEstimation of ORFs packaged in HF1 during generalised transduction if packaging terminates in the same location as for HF1 during lateral transduction. No phage genes are expected to be transduced during generalised transduction of the DNA sequence containing the tetracycline-resistance marker, so 100% of the transferred sequence is available for recombination and utilisation by the recipient cell.

^fThe total number of accessory ORFs utilisable by the recipient host cell is only a proportion of the total sequence transferred by HF1 because part of the phage genome is also packaged in the first headful during lateral transduction.