Histamine in food can cause intolerance reactions in consumers. Lactobacillus
parabuchneri (L. parabuchneri) is one of the major causes of elevated histamine
levels in cheese. Despite its significant economic impact and negative influence on
human health, no genomic study has been published so far. We sequenced and
analyzed 18 L. parabuchneri strains of which 12 were histamine positive and 6 were
histamine negative.We determined the complete genome of the histamine positive strain
FAM21731 with PacBio as well as Illumina and the genomes of the remaining 17 strains
using the Illumina technology.We developed the synteny aware ortholog finding algorithm
SynOrf to compare the genomes and we show that the histidine decarboxylase (HDC)
gene cluster is located in a genomic island. It is very likely that the HDC gene cluster
was transferred from other lactobacilli, as it is highly conserved within several lactobacilli
species. Furthermore, we have evidence that the HDC gene cluster was transferredwithin
the L. parabuchneri species.