Quantitative evaluation of the host-colonizing capabilities of the enteric bacterium Pantoea using plant and insect hosts

Abstract

The genus Pantoea is a highly diverse group comprising free-living, and both pathogenic and non-pathogenic host-associating species. Pathogenic isolates have been found to infect insects, plants and humans, yet it is unclear whether these isolates have similar pathogenic potential to the free-living environmental populations. Using MLSA of six housekeeping genes, we evaluated the phylogenetic relationships among 115 environmental and clinical (human) isolates representing 11 Pantoea species. An overlay of the location of isolation onto the resulting tree revealed that clinical and environmental isolates are interspersed, and do not form distinctive groups. We then conducted quantitative growth assays of our isolates using maize, onion and fruit flies as hosts. Notably, most clinical isolates were able to grow in both plant hosts often comparably or even better than the environmental isolates. There were no obvious growth or host colonization patterns that could distinguish those isolates with clinical potential. Growth of an isolate in one host could not be predicted based on its performance in another host, nor could host growth be predicted by phylogeny or source of isolation. This work demonstrates that the host-colonizing capabilities of all Pantoea species groups is unpredictable, indicating a broader host range and pathogenic potential than currently assumed.

Inheritance of Pantoea type III secretion systems through both vertical and horizontal transfer

“…The identification of the PSI-1b system in the clinical strain, P. calida B021323 was notable given previous work showing the plant pathogenic potential of many clinical strains and the animal pathogenic potential of environmental strains (Volksch et al 2009) (Nadarasah and. This discovery reinforces the notion that clinical strains of Pantoea are not necessarily dedicated animal pathogens, but may be plant pathogens or epiphytes that can colonize animal hosts opportunistically (Stavrinides 2009;Stavrinides et al 2010;Kirzinger et al 2011;Nadarasah and Stavrinides 2014).…”

“…BLAST was used to identify homologous nucleotide and amino acid sequences in 24 draft (Nadarasah and Stavrinides 2014;Smith et al 2013a;Smith et al 2013b;Walterson et al 2014), as well as publicly available Pantoea genomes (Supplemental Table 1), with E-value cutoffs < E-20. To construct the multi-locus sequence analysis species tree, the 16S rRNA, leuS, recA, and rpoB sequences were identified from each strain, concatenated, aligned using Clustal (Thompson et al 1994), and Neighbor-joining trees were constructed in MEGA version 5.0 (Tamura et al 2011) with 1000 bootstrap replicates.…”

Distinguishing nutrient‐dependent plant driven bacterial colonization patterns in alfalfa

“…Although Pantoea spp. colonize diverse host systems, colonization is not specific to the host organism or tissue from which it was isolated (Völksch et al ., ; Nadarasah and Stavrinides, ). The colonization abilities of Pantoea spp.…”

A wide diversity ofPantoealineages are engaged in mutualistic symbiosis and cospeciation processes with stinkbugs

“…Pantoea stewartii that causes the Stewart's vascular wilt in sweet corn and maize (Mergaert et al, 1993) and Pantoea agglomerans that causes crown and root gall disease of beet and Gypsophila (Cooksey, 1986;Burr et al, 1991). More recently, novel Pantoea species have been found in aquatic and terrestrial environments, as well as in association with a wide range of animals (Dillon et al, 2000;Brady et al, 2008;Aylward et al, 2012;Nadarasah and Stavrinides, 2014;Walterson and Stavrinides, 2015). Some Pantoea species are also consistently linked with human infections as well exemplified by Pantoea brenneri and Pantoea septica isolated only from clinical sources (Kratz et al, 2003;Schmid et al, 2003;De Baere et al, 2004;Lim et al, 2006;Van Rostenberghe et al, 2006;Fullerton et al, 2007).…”