Prevalence of Histidine Decarboxylase Genes of Gram-Positive Bacteria in as Revealed by qPCR.

Histamine is a degradation product of the bacterial decarboxylation of the amino acid histidine; such activity is determined by histidine decarboxylase encoded by a gene cluster, carried by some Gram-positive bacteria, that includes the gene. In this study, the presence of the gene in ready-to-eat samples collected from three producers based in Sweden was directly assessed via qPCR analysis for the very first time. Samples from producer A showed average gene abundance of 6.67 ± 0.13 Log cells/gene copies g; in samples from producer B the average value attested at 5.56 ± 0.06 Log cells/gene copies g, whereas for samples of producer C average gene abundance attested at 5.30 ± 0.08 Log cells/gene copies g. ANOVA showed a significantly higher average gene copy number in samples from producer A, whereas no significant differences were seen between average values of gene copy numbers detected in samples from producer B and C. The gene copies detected in the present study could give an estimation of the load of potential histamine-producing bacteria in .