Effect of eliminating hdcA gene of Staphylococcus epidermidis TYH1 on Histamine production

Safoora Pashangeh; Enayat Berizi; Majid Majlesi; Sajad Ghaderi; Victor Nizet; Samira Dahesh

doi:10.18502/ijm.v14i4.10239

Safoora Pashangeh Department of Food Science and Technology, School of Agriculture, Jahrom University, Jahrom, Iran
Enayat Berizi Department of Food Hygiene and Quality Control, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
Majid Majlesi Department of Nutrition, School of Health & Nutrition Sciences, Yasuj University of Medical Sciences, Yasuj, Iran
Sajad Ghaderi Department of Nutrition, School of Health & Nutrition Sciences, Yasuj University of Medical Sciences, Yasuj, Iran
Victor Nizet Department of Pediatrics, School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, USA
Samira Dahesh Department of Pediatrics, School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, USA

DOI: https://doi.org/10.18502/ijm.v14i4.10239

Keywords: Staphylococcus epidermidis; Histamine; Histidine decarboxylase; Capillary electrophoresis; Enterotoxin

Abstract

Background and Objectives: The possible adverse effect of histamine on human health has made it a detrimental aspect to the quality and safety of many fermented food products especially fish sauce.

Materials and Methods: In the present study, hdcA gene in Staphylococcus epidermidis TYH1 was knocked out and its effect on histamine production was evaluated. HdcA encodes histidine decarboxylase, an enzyme that produces histamine from histidine. Both strains of TYH1, the wild type (WT) and mutant (∆hdcA) were then incubated in tryptic soy broth (TSB) supplemented with histidine (0.5 mM). The histamine content determined by capillary zone electrophoretic (CZE) analysis. Safety assessment of this mutant of food origin was conferred by virulence genes.

Results: It was found that S. epidermidis TYH1 exhibited production of histamine (50.09 ± 0.06 μg/mL), while ∆hdcA strain of TYH1 exhibited no histamine forming activity. Safety assessment of ∆hdcA revealed the presence of nuc gene, while superantigenic toxins and coa genes were not observed. Therefore, it has the ability to be used as a starter culture to decrease the histamine content in any fermented food products.

Conclusion: Our study findings may contribute to provide a novel approach of promoting the food safety of fish sauce and other fermented food products regarding the regulation of histamine content.