الفهرس 
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Abstract
Microbiological study on some biogenic amines produced by food borne bacteria Biogenic amines are highly toxic substances that associated with food intake as a result of microbial decarboxylation process of amino acids. Several studies reviewed the role of food borne¬bacteria in biogenicamines formation. So, this study was designed to aim the following items:¬ I. Microbiological evaluation of some food samples: I.1. Microbiological examination: Meat, fish, cheese, pasterma, luncheon and herring were randomly collected from local market at Mansoura city, Egypt. Total viable count, proteolytic bacteria and Enterobacteriaceae member were determined. Obtained data showed that the predominance of proteolytic bacteria among the other tested groups was noticed. Meanwhile, the Enterobacteriaceae came in the last order. I.2. selection of biogenic amines producers: During the isolation, the bacterial isolates are randomly chosen and enumerated in potassium phosphate buffer (pH 7.0). This buffer containing amino acids of histidine, ornithine and lysine either separately or in combined form as a sole source of nitrogen and carbon. After that, the pH values were measured as indication of histidine, ornithine or lysine decarboxylases enzyme. The data obtained showed that ten bacterial isolates were selected according to their activity to decarboxylase enzymes for further studies. 1.3. pH indications of decarboxylases activities as a function of NaCl concentration: The data obtained showed that histidine, ornithine and lysine decarboxylase enzyme were respond to 1 and 3% NaCl. Meanwhile, 5% of NaCl was suppressor for decarboxylases enzyme. I.4. Quantitation of biogenic amines in meat samples inoculated with selected bacterial isolates: It is showed from the data that isolate No. CK1 produced high amount of histamine (31.8 mg/100g sample), but it was less productive for sperimidine compared to other. Also, it is found that isolate No. CHS1 was superior to the other examined strains in spermidine production that being 46.6 mg/100g sample. On the other hand, ?-phenylethyl amine was not found in inoculated samples with tested strains except isolate No. CHS2 that produced 0.173 mg/100g sample. Tryptamine was found in amounts of 0.55, 6.11, 8.47 and 4.30 mg/100g sample by isolate No. CHS1, isolate No. CK1, isolate No. CK2 and isolate No. CHS2, respectively. Cadaverine was produced by isolate No. CHS1, isolate No. CK1, isolate No. CK2 and isolate No. CHS2 in amount of 0.167, 0.467, 0.15 and 0.983 mg/100g sample, respectively. I.5. Identification of biogenic amines producers: The data obtained showed that bacterial isolates identified as, B. pumilus CHS1, E. cloaceae CHS2, E. aerogenos CK1 and E. aerogenes CK2 were selected according to high activity in amine production in meat samples. II. Toxicity of biogenic amines on mice: II.1. Physiological examination: II.1.1. In blood: The data obtained showed that the fold increase of serum albumin are 0.79, 0.96, 0.34 and 0.55 as a result of injection of 100 ?mol of histamine, cadaverine, putrescine and their mixture, respectively, compared to control. Also, the data showed that the fold increase of white blood cells (WBC?s) was found to be 1.24, 1.41, 1.70 and 1.37 by injection of histamine, cadaverine, putrescine and mixed amines. In addition, the fold increase of hemoglobin (Hb) was found to be 0.90, 0.75, 0.68 and 0.91 as a result of intra¬peritoneally injection of histamine, cadaverine, putrescine and mixed amines. II.1.2. In liver: The data obtained showed that the fold increase of aspartate amino transferase (Ast) was found to be 2.73, 2.40, 1.88 and 1.68, respectively. Meanwhile, the fold increase of alanine amino.