TABLE 1.

Biofilm-related genes identified in L. monocytogenes 15G01 through transposon insertions based on DNA homologies with the L. monocytogenes EGD genome database (accession number HG421741)^a

Function group and putative gene function	Transposon insertion site	Mean biofilm mass (%) relative to WT ± SD	No. of hits	Coordinate(s) for insertion in L. monocytogenes EGD	Orientation of transposon insertion	Mutant strainb
Biosynthesis
Adenylosuccinate synthase	LMON_0057 (purA)	135.7 ± 5.12	1	59174	3′–5′	24A10
Dihydroxyacetone kinase family protein	LMON_1882	173.03 ± 7.82	1	1888930	3′–5′	35H9
Acetyltransferase, GNAT family	LMON_2362	27.32 ± 6.92	1	2377834	5′–3′	31E7
Glycosyl hydrolase, family 31	LMON_2457	19.90 ± 4.93	1	–d	3′–5′	32E5
Cell wall/membrane
Sortase A, LPXTG-specific SrtA	LMON_0935	7.49 ± 0.59	1	948604	3′–5′	31C7
Glycosyltransferase	LMON_0939	18.74 ± 3.36	1	–	5′–3′	35C1
Putative peptidoglycan-bound protein (LPXTG motif) Lmo1666 homologue	LMON_1733	29.70 ± 5.66	3	1723653, 1721718, 1721318	5′–3′, 3′–5′, 3′–5′	24H3, 25D2, 64B3
Cardiolipin synthetase ClsA	LMON_2515	163.02 ± 15.27	2	2538121, 2538525	3′–5′, 5′–3′	30A9, 34F11
Glycosyltransferase LafA	LMON_2570	16.10 ± 2.43	2	2591134, 2590370	3′–5′, 3′–5′	28G11, 32A9
Translation and transcription
GTP-binding protein HflX	LMON_1358	16.06 ± 6.92	1	–	3′–5′	43C9
SSU ribosomal protein S1p	LMON_2007 (rpsA)	140.68 ± 10.74	1	2012734	3′–5′	28A2
Transporter systems
Manganese ABC transporter, ATP-binding protein SitB	LMON_1917	133.83 ± 7.38	1	1925244	3′–5′	47H11
Bacitracin export ATP-binding protein BceA	LMON_2188	138.01 ± 1.19	1	2194403	3′–5′	31G1
ABC transporter, permease protein EscB	LMON_2290	142.51 ± 7.66	2	2305608, 2305511	3′–5′, 3′–5′	32E2, 47H10
Phosphate ABC transporter, periplasmic phosphate-binding protein PstS	LMON_2511	30.81 ± 0.50	1	2532962	3′–5′	36A2
PTS system, IIA component	LMON_2675	32.69 ± 3.94	1	2692293	3′–5′	26C10
Mg2+ transport ATPase, P-type	LMON_2712	7.16 ± 1.47	2	2731046, 2731895	3′–5′, 3′–5′	30H2, 44D3
ABC transporter, ATP-binding protein	LMON_2792	6.93 ± 0.27	1	2816670	3′–5′	28D10
Motility
Flagellin protein FlaA	LMON_0695 (flaA)	23.74 ± 5.93	1	–	3′–5′	41H7
Autolysis
Membrane-bound lytic murein transglycosylase D precursor MltD	LMON_2714	2.11 ± 0.35	1	2734305	5′–3′	39G5
DNA repair and stress response
Glutamate decarboxylase	LMON_2376	6.81 ± 0.93	1	2393310	3′–5′	35F3
Excinuclease ABC subunit B UvrB	LMON_2501 (uvrB)	18.33 ± 2.58	2	2525427, 2525564	3′–5′, 3′–5′	33E11, 42G3
Unknown
FIG00774663: hypothetical protein	LMON_1212	21.32 ± 0.69	1	–	5′–3′	36B9
FIG00774466: hypothetical protein	LMON_2144	28.89 ± 3.37	1	2153693	5′–3′	26H1
COG1801: uncharacterized conserved protein	LMON_2417	15.37 ± 0.51	1	–	3′–5′	40C12
Hypothetical protein (mutant strain 44F5)	NCc	10.70 ± 5.02	1	–	3′–5′	44F5
Hypothetical protein (mutant strain 41A8)	NC	21.88 ± 7.19	1	–	3′–5′	41A8
Intergenice
Methionine ABC transporter ATP-binding protein and hypothetical protein	LMON_2430 and LMON_2431	18.27 ± 1.96	1	2450096	3′–5′	67C5
Dihydroxyacetone kinase family protein and putative alkaline-shock protein	LMON_1882 and LMON_1883	173.44 ± 15.52	1	1889436	3′–5′	33F8

^aHomologies were identified by Megablast and Geneious 7 software using default settings. The biofilm mass produced by the mutants (CV assay) was calculated relative to the biofilm formation by the wild type in two independent experiments with eight replicates. Putative gene functions are based on information from http://www.genome.jp/.

^bInternal numbering of the transposon library.

^cNC, no counterpart in L. monocytogenes EGD but present in the parental strain.

^d–, the exact insertion site could not be determined.

^eDefined by the two genes at each boundary of the intergenic space. 67C5 is 217 bp downstream of LMON_2430 and 100 bp upstream of LMON_2431, while 33F8 insertion is 7 bp downstream of LMON_1882 and 373 bp upstream of LMON _1883.