الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 116 |  |  |
| | | from | 116 | | |
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 bornebacteria 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 intraperitoneally 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 transferase was found to be 4.05, 3.65 and 1.12 during the intraperitoneally injection of cadaverine, putrescine and the mixture of amines. II.2. Histological examination: II.2.1. Liver: The histopathological studies of liver revealed necrotic heptocyte and vacuelar with histamine. Meanwhile, the mixture of histamine, cadaverine and putrescine causing lymphocyte infiltration around the central vein with intact liver architecture. II.2.2. Kidney: The data obtained showed that injected histamine dose of mice caused cloudy swelling of renal tubules with characteristic starshaped lumen. Meanwhile, the lymphocytic infiltration of interstial tissue of kidney with congested vessels were found in case of cadaverine injection. III. Inhibition of biogenic amines producers: III.1. Using lactic acid bacteria: a. In artificial media: Obtained data showed that L. helviticus had higher activity on BPB compared to L. acidophilus, in which the inhibition ratios were 100% for E. aerogenes CK1, E. aerogenes CK2 and E. cloaceae CHS2, while B. pumilus CHS1 showed to be much less persistent after incubation periods of 24 and 48 hr. Also, it is found that the high activity of L. helviticus is due to DROPping of the pH values and lactic acid production. In addition, it is noticed that neutralized lactic acid bacterial culture have no inhibitory effect on BPB. Meanwhile, nonneutralized of cultural fluid showed different inhibitory effect on BPB. b. In natural media: Generally, the data obtained showed that L. helviticus was effective in decreasing amines production by E. aerogenes CK1 compared to that obtained in case of B. pumilus CHS1. The fold increases of histamine were found to be 0.33 and 7.02 during associative growth of L. helviticus and E. aerogenes alone after 24 and 48 hr at 370C, respectively. Meanwhile, the fold increase of histamine was found to be 4.26 and 18.7 increase of L. helviticus with B. pumilus after 24 and 48 hr at 370C, respectively. The data showed that spermine was not detected in associative growth of L. helviticus and E. aerogenes, but it has fold increase of 22.15 after 48 hr during associative culture of L. helviticus and B. pumilus. The data obtained showed that the relative increase of B. pumilus number during associative growth with L. helviticus was found to be 0.26 and 0.07 after 24 and 48 hr at 370C. Meanwhile, the relative increase of E. aerogenes CK1 during associative growth with L. helviticus were 0.30 and 0.00g after 24 and 48 hr and 370C compared to growth of B. pumilus and E. aereogenes alone in natural medium. III.2. Using synthesized metallic complexes: a. In artificial media: Obtained data showed that B. pumilus CHS1 was more susceptible to gold and copper complexes, in which the diameter of inhibition zone were 14 and 12 mm, respectively. Meanwhile, E. cloaceae CHS2, E. aerogenes CK1 and E. aerogenes CK2 were resistant to zinc and copper complexes. b. In natural media: Data obtained showed that the fold increase of histamine by gold complex was found to be 3.13 and 21.42 after 24 and 48 hr at 300C. In addition, the fold increase of cadaverine and tryptamine were 39.16, 16.51, 806.2 and 52.0 after 24 and 48, respectively. Meanwhile, spermine was not detected during the incubation periods. The fold increase of histamine by copper complex was found to be 0.73 and 11.06 after 24 and 48 hr. Moreover, the fold increase of spermidine and putrescine of copper complex were 6.60, 3.19, 0.07 and 115.0 after 24 and 48 hr, respectively, compared to control. The data also obtained showed that the relative decrease in number of B. pumilus by copper complex was found to be 93.9 and 92.0% after 24 and 48 hr, whilst it was 61.5 and 84.0% by gold complex. The previous data obviously showed that these metallic complexes may be work as cofactor or prosthetic group for decarboxylase enzymes and in the same time lengthened the log phase of B. pumilus CHS1