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

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.

Capillary electromigration methods for food analysis and Foodomics: Advances and applications in the period March 2021 to March 2023

“…The application of basic electrolyte and negative pressure on the separation enhanced the separation of the isobaric amino acids leucine and isoleucine. 30 kV of voltage, and a hydrodynamic injection at 50 mbar for 3 s. This CZE-UV method confirmed the effectivity of the gene elimination due to histamine was not observed in the sample [28]. Different studies have shown that histamine is degraded by staphylococcal strains.…”

“…An allelic replacement of S. epidermidis was carried out to eliminate de gene and the histamine production was controlled by its determination by CZE–UV. CZE–UV analysis allowed a rapid and selective determination of histamine in 8 min using hydroxyisobutyric acid (60 mM) and sodium hydroxide (10 mM) at pH 3.3 as BGE, 30 kV of voltage, and a hydrodynamic injection at 50 mbar for 3 s. This CZE–UV method confirmed the effectivity of the gene elimination due to histamine was not observed in the sample [28]. Different studies have shown that histamine is degraded by staphylococcal strains.…”

“…On the other hand, some AAs of food can be transformed by the action of microorganism enzymes to Bas, which produce negative effects on the human body, such as headache, flush, or tachycardia, among other things [28,29]. Besides, the content of BAs in foods has to be exhaustively controlled as indicators of microbial food spoilage.…”

“…These compounds are formed by bacterial decarboxylation of free AAs, being a challenge the elimination of the gene of bacteria involved in the decarboxylation to decrease BAs contents in foods. In fact, Pashangeh et al developed a procedure to eliminate hdcA gene from Staphylococcus epidermidis isolated from fish to avoid the production of histamine [28]. An allelic replacement of S. epidermidis was carried out to eliminate de gene and the histamine production was controlled by its determination by CZE-UV.…”

“…In fact, Pashangeh et al. developed a procedure to eliminate hdcA gene from Staphylococcus epidermidis isolated from fish to avoid the production of histamine [28]. An allelic replacement of S. epidermidis was carried out to eliminate de gene and the histamine production was controlled by its determination by CZE–UV.…”