Archives of Microbiology (2018) 200:349–353
First report of a symbiotic relationship between Xenorhabdus griﬃniae
and an unknown Steinernema from South Africa
· Antoinette P. Malan
· Leon M. T. Dicks
Received: 13 July 2017 / Revised: 23 October 2017 / Accepted: 13 November 2017 / Published online: 23 November 2017
© Springer-Verlag GmbH Germany, part of Springer Nature 2017
Strain WS9, a mutualistic-associated bacterium, was isolated from an unknown entomopathogenic Steinernema nematode,
collected from a litchi orchard in Friedenheim, Mpumalanga, South Africa. Based on phenotypic and phylogenetic data of
the 16S rRNA, gltX, recA, dnaN, gyrB and infB gene sequences, strain WS9 is identiﬁed as X. griﬃniae. Strain WS9 has
antibacterial activity against Gram-positive and Gram-negative bacteria. This is the ﬁrst report of an association between X.
griﬃniae and an unknown Steinernema species from South Africa.
Keywords Entomopathogenic nematodes · Mutualistic bacterium · Taxonomy · 16S rRNA
Members of the genus Xenorhabdus are Gram-negative,
asporogenic, fermentative, facultative anaerobic rods with
a respiratory and fermentative metabolism, and belong to the
family Enterobacteriaceae. They grow optimally at 28 °C,
are oxidase and catalase negative and do not reduce nitrate
to nitrite (Thomas and Poinar 1997; Akhurst and Boemare
2005). Acid is produced from the fermentation of glucose,
but without the release of CO
. N-acetyl-glucosamine, glyc-
erol, fructose and mannose are usually fermented (Akhurst
and Boemare 2005). Xenorhabdus species are known to
produce two phenotypic variants that diﬀer in morphology
and physiology. Phase I cells are larger than phase II cells,
absorb certain dyes and produce proteases, lipases and anti-
biotics (Akhurst 1980; Boemare and Akhurst 1988).
Xenorhabdus spp. are closely associated with
entomopathogenic nematodes of the family Steinernemati-
dae that infects insects such as Lepidoptera, Diptera, Orthop-
tera, Coleoptera and Hymenoptera (Laumond et al. 1979;
Poinar 1979). Although the association between Xenorhab-
dus spp. and nematodes is species-speciﬁc, a single species
may infect diﬀerent Steinernema spp. (Fischer-Le Saux et al.
1997; Lee and Stock 2010). More than 20 Xenorhabdus spe-
cies have been characterised, with approximately 11 of these
species being associated with more than one Steinernema
nematode species (Tailliez et al. 2006; Stock 2015).
Steinernema dauer larvae or non-feeding infective juve-
nile (IJ) transport Xenorhabdus to the haemocoel by enter-
ing natural openings on the body of the insect. Once in the
haemocoel, the IJ nematodes release an immunesuppressive
agent that suppresses the activity of antimicrobial peptides
produced by the insect (Götz et al. 1981). IJ develop into
amphimictic females and males that feeds on the prolifer-
ating bacteria. Endo- and exotoxins (e.g., DNases, lipases
and lecithinases) are released by the bacteria, killing the
insect within 24–48 h. Colonization of the cadaver by other
microorganisms is prevented by the release of antimicro-
bial compounds from the respective Xenorhabdus species.
The bacteria and bio-converted host tissue supports the
sexual reproduction of the nematodes as long as nutrients
are available. The nematodes, colonized with a few cells
of Xenorhabdus are then released into the environment to
repeat the cycle of infection (Adams and Nguyen 2002).
Communicated by Erko Stackebrandt.
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s00203-017-1452-4) contains
supplementary material, which is available to authorized users.
* Leon M. T. Dicks
Department of Microbiology, University of Stellenbosch,
Private Bag X1, Matieland 7602, South Africa
Department of Conservation Ecology and Entomology,
University of Stellenbosch, Private Bag X1, Matieland 7602,