TY - JOUR
T1 - Motility is required for the competitive fitness of entomopathogenic Photorhabdus luminescens during insect infection
AU - Easom, Catherine A
AU - Clarke, David J
PY - 2008/10/3
Y1 - 2008/10/3
N2 - Background: Photorhabdus are motile members of the family Enterobactericeae that are
pathogenic to insect larvae whilst also maintaining a mutualistic interaction with entomophagous
nematodes of the family Heterorhabditiae. The interactions between Photorhabdus and its hosts are
thought to be an obligate part of the bacteria's life-cycle in the environment. Motility often plays a
key role in mediating bacteria-host interactions and, in this study, we were interested in
characterising the role of motility in the Photorhabdus-nematode-insect tripartite association.
Results: We constructed deletion mutants of flgG (blocking flagella production) and motAB
(blocking flagella rotation) in P. luminescens TT01. Using these mutants we show that both the ΔflgG
and ΔmotAB mutants are equally as good as the wild-type (WT) bacteria in killing insects and
supporting nematode growth and development suggesting that flagella production and motility are
not required for pathogenicity or mutualism. However we show that the production of flagella is
associated with a significant metabolic cost during growth on agar plates suggesting that, although
not required for pathogenicity or mutualism, there must be a strong selective pressure to retain
flagella production (and motility) during the interactions between Photorhabdus and its different
hosts. To this end we show that both the ΔflgG and ΔmotAB mutants are out-competed by WT
Photorhabdus during prolonged incubation in the insect revealing that motile bacteria do have a
fitness advantage during colonisation of the insect larva.
Conclusion: This is the first report of a role for motility in Photorhabdus and we show that,
although not required for either pathogenicity or mutualism, motility does contribute to the
competitive fitness of Photorhabdus during infection of the insect (and, to a lesser extent, the
nematode). This adaptive function is similar to the role ascribed to motility in mammalian
pathogens such as uropathogenic Escherichia coli (UPEC). Therefore, in addition to describing a role
for motility in Photorhabdus, this study reinforces the relevance and utility of this bacterium as a
model for studying bacteria-host interactions.
AB - Background: Photorhabdus are motile members of the family Enterobactericeae that are
pathogenic to insect larvae whilst also maintaining a mutualistic interaction with entomophagous
nematodes of the family Heterorhabditiae. The interactions between Photorhabdus and its hosts are
thought to be an obligate part of the bacteria's life-cycle in the environment. Motility often plays a
key role in mediating bacteria-host interactions and, in this study, we were interested in
characterising the role of motility in the Photorhabdus-nematode-insect tripartite association.
Results: We constructed deletion mutants of flgG (blocking flagella production) and motAB
(blocking flagella rotation) in P. luminescens TT01. Using these mutants we show that both the ΔflgG
and ΔmotAB mutants are equally as good as the wild-type (WT) bacteria in killing insects and
supporting nematode growth and development suggesting that flagella production and motility are
not required for pathogenicity or mutualism. However we show that the production of flagella is
associated with a significant metabolic cost during growth on agar plates suggesting that, although
not required for pathogenicity or mutualism, there must be a strong selective pressure to retain
flagella production (and motility) during the interactions between Photorhabdus and its different
hosts. To this end we show that both the ΔflgG and ΔmotAB mutants are out-competed by WT
Photorhabdus during prolonged incubation in the insect revealing that motile bacteria do have a
fitness advantage during colonisation of the insect larva.
Conclusion: This is the first report of a role for motility in Photorhabdus and we show that,
although not required for either pathogenicity or mutualism, motility does contribute to the
competitive fitness of Photorhabdus during infection of the insect (and, to a lesser extent, the
nematode). This adaptive function is similar to the role ascribed to motility in mammalian
pathogens such as uropathogenic Escherichia coli (UPEC). Therefore, in addition to describing a role
for motility in Photorhabdus, this study reinforces the relevance and utility of this bacterium as a
model for studying bacteria-host interactions.
UR - http://www.scopus.com/inward/record.url?scp=54049083392&partnerID=8YFLogxK
UR - http://dx.doi.org/10.1186/1471-2180-8-168
U2 - 10.1186/1471-2180-8-168
DO - 10.1186/1471-2180-8-168
M3 - Article
SN - 1471-2180
VL - 8
SP - 168
JO - BMC Microbiology
JF - BMC Microbiology
IS - 1
ER -