Spontaneous mutations in the flhD operon generate motility heterogeneity in Escherichia coli biofilm

BMC Microbiology

Table 1 Summary of phenotypes for isolates that were recovered from biofilm of MC1000

Incubation	# of col.	Motility^a	Colony designations^b	pXL27 compl.^c	PCR1/PCR2^d				PCR3^e
					Partially Motile	Non-Motile
					Partially Motile	Category I	Category II	Category III
7d	368	4 NM (1 %)	JS28-31	4 col. PM		4 col. with parental PCR fragments			ND
7d	368	9 PM (2.4 %)	JS19-JS27	ND	9 col. with parental PCR fragments				ND
14 d	1217	58 NM (4.8 %)	JS18, JS42-79, JS82-JS100	54 col. FM, 4 col. PM		21 col. with parental PCR fragments	3 col. lacking a PCR1 product, 3 col. lacking a PCR2 product	31 col. with extended PCR fragments in both reactions	31 col. tested: 6 col. JS44 orient, 22 col. JS90 orient, 3 col. no PCR3 fragments
14 d	1217	14 PM (1.1 %)	S17, JS32-JS41, JS80, JS81, JS101	ND	14 col. with parental PCR fragments				ND

^aMotility was determined on motility plates: NM, the isolate was completely non-motile; PM, the isolate exhibited partial motility relative to its parent strain
^bAll 85 MC1000 biofilm isolates that exhibited reduced motility relative to MC1000 were given JS designations
^c Non-motile isolates from MC1000 biofilm were tested for complementation with pXL27: FM, at least 7 of 8 transformants exhibited the full motility of the parent; PM, fewer than 7 of 8 transformants were fully motile or all colonies were partially motile. ND, not determined
^dReduced motility isolates from MC1000 biofilm were subjected to PCR1 and PCR2 to test for insertions/deletions within the flhD operon
^eThe 31 isolates from category III were subjected to PCR3 to identify IS1 insertions

ISSN: 1471-2180