ABSTRACT
Hormones are used in veterinary medicine for different purposes such as treatment, improving animal products, obstetrical cycles, breed performances and enhancing acceptability of feed. The most dangerous drug residues presented in food of animal origin are because of neglecting withdrawal time, masking the sign of diseases in slaughterhouse and using unapproved drugs. Hormone residues in food of animal origin have health impacts on consumers. This survey have been done for determining the probable presence of the most used and dangerous hormones in pasteurized milk distributed in Tehran, capital of Iran. 50 samples of pasteurized milk were randomly collected from Tehran market from different brands and fats [low, standard and full]. Residues of phenylbutazone [PBZ] and Dexamethasone [DXM] were detected by HPLC-UV method according to AOAC instructions. ELISA was applied for measuring of 17- beta Estradiol residues. Minimum detectable residue of PBZ in milks was 2.5 ng/ml. 45 samples [90%] had PBZ from 1 to 58 ng/ml [Minimum Residues Level [MRL] for PBZ in cow milk must be zero per milliliter]. Minimum detectable residue of DXM in milks was 5 ng/ml, which in 30 [60%] samples was more than 5 ng/ml [MRL for DXM in cow milk must be 0.3 ppb]. In 8 samples out of 50 [16%] residues of 17- beta Estradiol was more than natural hormone residue [natural residues of 17- beta Estradiol in milk is 10-30 pb/ml]. Although hormones are vital for many physiological functions of humand beings, but exceeding of them in the body make many health problems. PBZ residue in 90%, DXM in 60% and 17- beta Estradiol in 16% of milk samples pointing a dangerous situation of using veterinary drugs in food animals and their milks
ABSTRACT
Proteases are among the most important industrial enzymes. Alkaline proteases are used primarily as cleansing additives. As alkaline pH and temperature stability are two main important factors of enzyms for their addition to detergents' formula, it is desirable to search for new proteases with novel properties from different sources. The purpose of this study was to isolate an alkalophilic bacillus sp. with possibility of alkaline protease production and then purification of the produced alkaline protease. Isolation and purification of proper colonies from soil samples were performed. After characterization of taxonomic and biochemical specifications of colonies, they were cultivated in a specific liquid culture medium [alkaline pH] and then selected bacillus 2-5 was cultivated in a proper culture medium. The enzyme was isolated and purified as fallows: 1- Ammonium sulfate precipitation [saturation percentage, 55%] 2- Ultra filtration 3- Cation exchange chromatography [CM- cellulose]. Alkaline protease activity was checked by determination of equal concentration of tyrosine as a product at lamda=275 nm after alkaline hydrolysis of casein as a substrate. Bacillus 2-5 was selected because only it had growth and alkaline protease activity. It had both amylolitic and proteolytic activities at alkaline pHs but no gelatinolytic activity was found. Purification progression was demonstrated by gel electrophoresis [PAGE]. Molecular weight of alkaline protease by SDS-PAGE and was measured by using protein standard solutions this was 24700 Dal. The yield of purification was 24% and parification, was 50 times gain factor, as found by other researchers. The purified enzyme was monomer because electrophoretic mobility at PAGE was the same as SDS-PAGE