Effect of eliminating hdcA gene of Staphylococcus epidermidisTYH۱ on Histamine production

Background and Aim : The possible adverse effect of histamine on human health has made it adetrimental aspect to the quality and safety of many fermented food products especially fish sauce.Methods : In present study, hdcA gene in Staphylococcus epidermidis TYH۱ was knocked outand its effect on histamine production was evaluated. HdcA encodes histidine decarboxylase, anenzyme that produces histamine from histidine. Both strains of TYH۱, the wild type (WT) andmutant (ΔhdcA) were then incubated in tryptic soy broth (TSB) supplemented with histidine (۰.۵mM). The histamine content determined by capillary zone electrophoretic (CZE) analysis. Safetyassessment of this mutant of food origin was conferred by virulence genes.Results : It was found that S. epidermidis TYH۱ exhibited production of histamine (۵۰.۰۹?۰.۰۶?g/mL), while ?hdcA strain of TYH۱ exhibited no histamine forming activity. Safety assessmentof ?hdcA revealed the presence of nuc gene, while superantigenic toxins and coa genes were notobserved. Therefore, it has the ability to be used as a starter culture to decrease the histaminecontent in any fermented food products.Conclusion : Our study findings may contribute to provide a novel approach of promoting thefood safety of fish sauce and other fermented food products regarding the regulation of histaminecontent.

کلیدواژه ها:

Staphylococcus epidermidis ، histamine ، histidine decarboxylase ، capillaryelectrophoresis ، enterotoxin