Identification of Histamine-producing Bacteria Isolated from Fish and Its Products

Abstract

Histamine and biogenic amines (BA) produced due to spoilage of fish and fish products represent health risk to human food intoxication. The current survey was conducted to identify the most common histamine producing bacteria in fish and fish products in Egypt. One hundred and fifty samples (Tilapia, Sardines, Smoked herring, Mackerel, Filet of Carp, Morgan, and Mugil) collected from Giza retail shops were investigated bacteriologically by conventional identification methods. The results indicated that the most frequently isolated species were Klebsiella (33.3%), Staphylococci (24.7%), Salmonella (22.7%), E. coli (18.7%), Pseudomonas (18%), Proteus (16.7%) and Vibrio (6.7%) species. Using ELISA test, 15 out of 150 examined fish and fish products samples (10%) had histamine in their tissues. The level of histamine found in Fesikh was 50 - 50.8 mg/100mg, Carp fillet 22.5, Smoked herring (Ringa) 8 -10, and Mackerel 20.6 – 23, Sardine 17.55- 23, Morgan 12.59 and Tilapia 8.97-9.76 mg/100mg. The bacterial isolates among the 15 histamine positive fish were cultivated on Niven’s agar to detect the histamine producing bacteria. It is clear that Enterobacteriaceae was the common histamine producing isolates. 32.23 % of total pure screened cultures were positive for the presence of hdc gene. Estimation of health risk and hazard index associated with the consumption of fish and fish products contaminated with histamine producing bacteria with estimated concentrations. The estimated daily intake of histamine in fish and fish products indicated that Fesikh recorded the highest EDI Hist. 122.4 mg/g, while both Ringa and Tilapia recorded the lowest values (21.86, 22.83 mg/g respectively). Target hazard quotient in each type of fish and fish product revealed that all values were still less than 1.0 despite Fesikh was still showing the highest THQ and HRI (0.47, 0.41 respectively) compared with other examined fish types. The current