Whole-Genome Sequence and Pathogenicity Analysis of Providencia Heimbachae Causing Diarrhea in Weaned Piglets

Providencia heimbachae was previously identified in piglets with post-weaned diarrhea and associated with hindlimb paralysis. However, the pathogenic mechanisms and virulence factors of P. heimbachae are not fully known. Whole-genome sequence analysis will be helpful to extend our understanding of the characterization of P. heimbachae at a genomic level. In this study, we sequenced the whole genome of P. heimbachae for the first time using PacBio RS II sequencers and assembled de novo through hierarchical genome assembly process (HGAP). Furthermore, we performed further genome annotation. The genome of P. heimbachae 99101 consists of a circular chromosome (4,262,828 bp) and a circular plasmid (231,957 bp) with G + C contents of 40.43 and 47.16%, respectively. Genome-wide sequence analysis yielded a total of 286 predicted virulence factors, 178 resistance genes, 17 chaperone protein manipulators of fimbriae, 47 genes involved in the encoding of flagellin, 12 cell membrane-associated virulence genes, 18 Enterobacteriaceae common antigens, etc. Based on genome analysis, we preliminarily confirmed through animal experiments that the capsule was the virulence factor of P. heimbachae causing hindlimb paralysis in animals. Our study provides a genetic basis for further elucidation of the characteristics and functional mechanisms of P. heimbachae as a conditionally pathogenic bacterium, as well as a direction for research into the mechanism of action of P. heimbachae infecting humans, extending knowledge of P. heimbachae as an important zoonotic pathogen.