Listeria marthii sp. nov., isolated from the natural environment, Finger Lakes National Forest

Abstract

Four isolates (FSL S4-120 T , FSL S4-696, FSL S4-710, and FSL S4-965) of Gram-positive, motile, facultatively anaerobic, non-spore-forming bacilli that were phenotypically similar to species of the genus Listeria were isolated from soil, standing water and flowing water samples obtained from the natural environment in the Finger Lakes National Forest, New York, USA. The four isolates were closely related to one another and were determined to be the same species by whole genome DNA-DNA hybridization studies (.82 % relatedness at 55 6C and .76 % relatedness at 70 6C with 0.0-0.5 % divergence). 16S rRNA gene sequence analysis confirmed their close phylogenetic relatedness to Listeria monocytogenes and Listeria innocua and more distant relatedness to Listeria welshimeri, L. seeligeri, L. ivanovii and L. grayi. Phylogenetic analysis of partial sequences for sigB, gap, and prs showed that these isolates form a wellsupported sistergroup to L. monocytogenes. The four isolates were sufficiently different from L. monocytogenes and L. innocua by DNA-DNA hybridization to warrant their designation as a new species of the genus Listeria. The four isolates yielded positive reactions in the AccuProbe test that is purported to be specific for L. monocytogenes, did not ferment L-rhamnose, were nonhaemolytic on blood agar media, and did not contain a homologue of the L. monocytogenes virulence gene island. On the basis of their phenotypic characteristics and their genotypic distinctiveness from L. monocytogenes and L. innocua, the four isolates should be classified as a new species within the genus Listeria, for which the name Listeria marthii sp. nov. is proposed. The type strain of L. marthii is FSL S4-120 T (5ATCC BAA-1595 T 5BEIR NR 9579 T 5CCUG 56148 T ). L. marthii has not been associated with human or animal disease at this time.

The arsenal of virulence factors deployed byListeria monocytogenesto promote its cell infection cycle

“…5,6 These ubiquitous bacteria are commonly isolated from plants, soil and water and L. monocytogenes is capable to contaminate agriculture environments, animal feed and foods. 7 The pathogenic species L. monocytogenes causes disease in humans and animals, whereas L. ivanovii only affects animals, mainly sheep and cattle.…”

Outbreak of encephalitic listeriosis in red-legged partridges (Alectoris rufa)

“…Molecular sequence analysis was carried out on the original isolate from partridge 1Ab to confirm identity of the strain and to establish its relationship with other Listeria isolates. Analysis was carried out in comparison with a recent detailed analysis that described a novel species Listeria marthii (Graves et al, 2010). Sequencing and phylogenetic analysis of the partial 16S rRNA gene, as shown in Figure 3, demonstrated that the isolate is most closely related to L. monocytogenes strains including the type strain NCTC 10357.…”

“…Sequencing and phylogenetic analysis of the partial 16S rRNA gene, as shown in Figure 3, demonstrated that the isolate is most closely related to L. monocytogenes strains including the type strain NCTC 10357. In order to obtain more phylogenetic information a more comprehensive analysis was carried out using concatenated sequences of three housekeeping genes (sigB, prs and gap) and undertaking direct comparison with previous analyses (Graves et al, 2010). As illustrated in Figure 4 these analyses provided more precise description of the isolate placing it clearly within lineage II of L. monocytogenes.…”

“…In order to provide preliminary molecular confirmation of isolate identity the virtually complete 16S rRNA gene was amplified from the initial L. monocytogenes isolate of the brain of a red-legged partridge (bird 1Ab) by PCR using primer pair 5′ AGTTTGATCCTGGCT-CAG 3′ and 5′ ACCTTGTTACGACTT 3′ and sequenced using a series of internal primers as described previously (Hunt et al, 2013). Phylogenetic analysis previously described by Graves et al (2010) was reproduced to confirm placement of the isolate relative to reference strains of Listeria. Phylogenetic analysis was performed using the MEGA5 programme (Tamura et al, 2011) as described in figure legends.…”

“…Phylogenetic analysis was performed using the MEGA5 programme (Tamura et al, 2011) as described in figure legends. In order to further characterize phylogenetic position, sequencing of fragments of additional housekeeping genes (sigB, gap and prs) was also performed as described by Graves et al (2010) and phylogenetic analysis was performed as above with reference to the sequences included in Graves et al (2010).…”