Abstract
Ewingella americana is a cosmopolitan bacterial pathogen that has been isolated from many hosts. Here, we sequenced a high-quality genome of E. americana B6-1 isolated from Flammulina filiformis, an important cultivated mushroom, performed a comparative genomic analysis with four other E. americana strains from various origins, and tested the susceptibility of B6-1 to antibiotics. The genome size, predicted genes, and GC (guanine-cytosine) content of B6-1 was 4.67 Mb, 4301, and 53.80%, respectively. The origin of the strains did not significantly affect the phylogeny, but mobile genetic elements shaped the evolution of the genus Ewingella. The strains encoded a set of common genes for type secretion, virulence effectors, CAZymes, and toxins required for pathogenicity in all hosts. They also had antibiotic resistance, pigments to suppress or evade host defense responses, as well as genes for adaptation to different environmental conditions, including temperature, oxidation, and nutrients. These findings provide a better understanding of the virulence, antibiotic resistance, and host adaptation strategies of Ewingella, and they also contribute to the development of effective control strategies.
Highlights
Ewingella americana is a Gram-negative, oxidase-negative, catalase-positive, lactose-fermenting, non-fluorescent, rod-shaped, motile, and facultatively anaerobic bacterium [1]
Strain B6-1 was confirmed as E. americana from the phenotypic, biochemical characters (Supplementary Table S1), and the 16S rRNA gene phylogenetic analysis from previous work [10]
The whole-genome sequence of E. americana B6-1 was assembled into one circular chromosome
Summary
Ewingella americana is a Gram-negative, oxidase-negative, catalase-positive, lactose-fermenting, non-fluorescent, rod-shaped, motile, and facultatively anaerobic bacterium [1]. The bacterium was first isolated from clinical sources and described by Grimont et al in 1983 [2] as a new genus and species in the family Enterobacteriaceae. The genus Ewingella is currently transferred to the class. E. americana is the only known species in the genus. The bacterium has a wide range of hosts, including human [3], mollusks [4], plants [5,6], vacuum-packed meat [7], nutria carcasses [8], and mushrooms [9,10,11]. E. americana is known to cause internal stipe necrosis in Agaricus bisporus [9,12] and brown rot on cultivated Flammulina filiformis [10]
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