الفهرس 
Introduction
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Abstract
A total of 450 random samples of raw milk and some locally manufactured dairy products including raw milk (150) samples, soft cheeses (Damietta and Kareish cheeses, 50 samples of each), ice-cream (100) samples, yoghurt (50) samples and cooking butter (50) samples and were collected from street vendors, weekly town market, dairy farms and dairy shops in Assiut Governorate. These samples were examined bacteriologically for enumeration, isolation and identification of Prototheca species using two media Sabouraud dextrose agar (SD) and Prototheca isolation media (PIM) agar.
The result revealed that 54 (36%), 38 (76%), 42 (84%), 10 (10%), 34 (68%) and 22 (44%) of the examined raw milk, Damietta cheese, Kareish cheese, ice-cream, yoghurt and cooking butter samples were contaminated with Prototheca spp. on SD agar. However, the incidence of Prototheca spp. on PIM agar was 37 (24.7%), 25 (50%), 30 (60%), 6 (6%), 26 (52%) and 16 (32%) in the same samples, respectively.
P. zopfii was isolated in a percentage of 22.2%, 26.3%, 28.6%, 50%, 32.3% and 22.7% from the examined raw milk, Damietta cheese, Kareish cheese, ice-cream, yoghurt and cooking butter samples, respectively on SD agar and in a percentage of 24.3%, 40%, 36.7%, 66.7%, 26.9% and 37.5% from the same samples, respectively on PIM agar.
P. blaschkeae could be isolated in a percentage of 27.8%, 21.1%, 19%, 10%, 23.5% and 18.2% from the examined raw milk, Damietta cheese, Kareish cheese, ice-cream, yoghurt and cooking butter samples, respectively on SD agar, and in a percentage of 22%, 28%, 26.7%, 33.3%, 23.1% and 37.5% from the examined same samples, respectively on PIM agar.
P. stagnora could be isolated in a percentage of 40.7%, 42.1%, 45.2%, 20%, 44.1% and 40.9% from the examined raw milk, Damietta cheese, Kareish cheese, ice-cream, yoghurt and cooking butter samples, respectively on SD agar, and in a percentage of 46%, 28%, 20%, 38.5% and 25% from the examined raw milk, Damietta cheese, Kareish ceese, yoghurt and cooking butter samples, respectively on PIM agar.
P. wickerhamii was also associated in a percentages of 9.3%, 7.1%, 10.5%, 20% and 18.2% from the examined raw milk, Damietta cheese, Kareish cheese, ice-cream and cooking butter samples, respectively on SD agar, and in a percentage of 8.1%, 4%, 16.7% and 11.5% from the examined raw milk, Damietta cheese, Kareish cheese and yoghurt samples, respectively on PIM agar.
Comparison between SD and PIM agar for isolation of Prototheca spp. revealed the superiority of SD, however, the use of one medium was not enough for isolation of Prototheca spp.
The effect of Nigella sativa seed and oil on the survival of
P. zopfii was evaluated by adding different concentrations of seed and oil (1%, 5% seed and 1%, 3% oil) in Damietta cheese which was laboratory prepared, inoculated with the previously isolated and identified P. zopfii to yield a concentration of 1.0 x 107 c.f.u./ml or gm at room (25 + 2oC) and refrigerator (5 + 2oC) temperature. P. zopfii counts, pH value, and salt were determined.
The sensitivity of P. zopfii to Nigella seed and oil was demonstrated by a reduced count on SD agar. The counts were decreased and reached 2 x 103, 1.1 x 103 and 2 x 102 in 1% seed, 5% seed and 1% oil at room temperature, during the fourth week of storage and P. zopfii not detected at 3% Nigella sativa oil. While, at refrigerator temperature, the counts were decreased and reached to 9 x 102, 1 x 102 and 70 x 10 in 1% seed, 5% seed and 1% oil during third week of storage and P. zopfii not detected at 3% Nigella sativa oil. Also, the results revealed that the effect of Nigella oils higher than seeds on the inhibition of P. zopfii.
The effect of Natamycin on the survival of P. zopfii using different concentrations of Natamycin (0.2%, 0.4%) in Feta cheese which was laboratory prepared, inoculated with the previously isolated and identified P. zopfii to yield a concentration of 2 x 108 c.f.u./ml or gm at room temperature (25 + 2oC) and refrigerator temperature (5 + 2oC). P. zopfii counts were demonstrated and PH value were determined every twelve hours.
P. zopfii couldn’t be detected after 24h and after curd in the samples of Feta cheese containing Natamycin of 0.2%, 0.4% in storage at room and refrigerator temperature, respectively.
The public health significance of the organism and the precautions, which should be taken to control this organism and the precautions, which should be taken to control this organism in dairy industry as well as the recommended sanitary measures, were also discussed.