7 ± 0.5um; n = 8) 3841 flaA – BCDEHG 8 – Almost all cells are non-flagellated; only one cell with very thin, short appendage 3841 flaB – ACDEHG 47 + Truncated (2.2 ± 0.5um; n = 6) 3841 flaC – ABDEHG 30 ++ ND 3841 flaD – ABCEHG 87 +++ ND 3841 flaE – ABCDHG 39 ++++ Truncated (3.4 ± 0.3 um; n = 5) GF120918 3841 flaH – ABCDEG 54 +++ Truncated (2.4 ± 0.6 um; n = 12) 3841 flaG – ABCDEH 96 ++ ND 3841 flaB/C/D – AEHG 26 + Truncated (1.9 ± 0.6 um; n = 13) 3841 flaA/B/C/D – EHG – - ND Strain VF39SM selleck kinase inhibitor ABCDEHG 100 +++++ Normal (5.1 ± 0.5 um; n = 13) VF39SM flaA – BCDEHG – - No flagella VF39SM flaB – ACDEHG 41 ++ Truncated (1.6 ± 0.5 um; n = 6); reduced
number of filaments (1-2 filaments/cell) VF39SM flaC – ABDEHG 49 ++ Truncated (2.1 ± 0.5 um; n = 9); reduced number of filaments (1-2 filaments/cell) SC79 VF39SM flaD – ABCEHG 85 ++++ Normal number and length; thinner filaments VF39SM flaE – ABCDHG 92 ++++ Normal VF39SM flaH – ABCDEG 97 +++++ Normal VF39SM flaG – ABCDEH 100 +++ Normal; slightly reduced number of filaments VF39SM flaB/C/D – AEHG 25 + Truncated (1.6 ± 0.3 um; n = 13); reduced number of filaments (1-2 filaments/cell) VF39SM flaA/B/C/D – EHG – - No flagella *Percentage relative to wildtype swimming diameter. Means of at least two replicates. (-) means non-motile; † As observed by TEM; ND means not determined; values in parenthesis refer to the average length of a flagellar filament ± standard deviation.
The lengths of the flagella formed by the fla mutants are significantly Fossariinae different from the flagella formed by the wildtype strain (P < 0.0001). The swimming motility of the 3841 flaA mutant was significantly reduced while the VF39SM flaA mutant was non-motile
on swimming plates. Complementation of 3841 flaA and VF39SM flaA mutants with pBBRMCS1-MCS5::flaA completely restored swimming motility, confirming that swimming defects were due to loss of flaA. Both of the flaA mutants were also unable to swarm. The VF39SM flaA mutant strain was non-flagellated (Fig. 4a). Most of the 3841 flaA mutants observed by TEM were non-flagellated. Only one cell was observed to possess a very thin and short appendage (Fig. 5). Individual mutations in flaB for both 3841 and VF39SM, and flaC for VF39SM resulted in a reduced number of flagella and shorter filaments (Fig. 4b and 4c; Fig. 5), which could account for the considerable reduction in swimming and swarming motility (Table 2). The lengths of the flagellar filaments formed by the VF39SM flaB and VF39SM flaC mutants were reduced to around half of the wildtype flagellum. Mutation of flaB in 3841 also resulted in the synthesis of shorter filaments, exhibiting an average length of 2.2 μm. In terms of the number of filaments formed, almost all of the VF39SM flaB – and VF39SM flaC – cells observed exhibited only one flagellum per cell compared with the 4-7 flagella formed by the wildtype strain.