Study On Detection Of Residue In Milk By Bacillus Stearothermophillus

This paper studied the detecting antibiotics residual in milk with Bacillus stearothermophilus's gemmas of embeded. I have studing some indexs for increasing the method's sensitivity and stability. These indexs are nutritive substances, indicator's quantities, conditiones of embedded and conditiones of detected ect. By to contrasting with subsample fermentation method, encoding standard (TTC) methed, kit (ECLIPSE50) method and paper method which these four methods, then statistics positive rates and further to confirm the article's experiment method's feasibility and sensitivity.This empirical studing mainly including below several aspects :1. First we let the test organism of purchase (ATCC12980=NCTC10339) form CGMCC rejuvenescent, optimize and cultured at the tryptone-soy-agar medium. let they growth in the condition that temperature is 65℃and pH value is 7.2, then choice colonys which growth fast. Bacillus stearothermophilus's colonys only have pinhead-sized. they are Gram-positive bacteria.2. To prepare gemmas of Bacillus stearothermophilus .in this experiment have two methods can to get rid of nutrition thallus from gemmas soliquoid, one is lysozyme method the other is to heat and centrifuge. By the two methods to contrast, and to consider the cost factor, I choose to heat and centrifuge method in the article. After cultured inclined plane strain washed lawn with normal sodium, succussed, filtered, make it to some density gemmas soliquoid, and then heated and centrifuged. gemmas soliquoid in 70℃heated 10 minutes can survival more gemmas , the effective is best than higher temperature and heating more time.3. Embedded gemmas of Bacillus stearothermophilus :by contrasting the four medium of gel strength, diffusibility, simple and easy level of operating that carrageenan, gellan gum, guar gum, calcium alginate . I choose calcium alginate for gemmas medium of Bacillus stearothermophilus.each detection tubule are to put two or three gelatum beads . sealled up at 0~4℃until used.4. The optimization medium to use direct cross experiment is glucose 1%, peptone 1%. The pH value of medium is controlling about 7.2, every 100mL medium are added to 0.06mL 1.6% of indicator. 5. Determine the detection of condition: raw milk sample after treated , every detection tubule are to add 0.2 mL purple medium then to put 0.1mL treated milk sample, at 65℃are culturing 2.5 hours.I take detection samples 200 in all , detection time are 135 minutes, negative samples are 173 and positive samples are 27, no doubtful sampl- es , positive rates are 13.5%, so this studiing method to have feasi- bility.6. Stability experiment: detection tubules were put in to 4℃until one month , every week detect once , record they are negative time , front three weeks detection time are 135 minutes, the fourth week detection time are 150 minutes, but all the time are normal . so this experiment's detection stability is one month.7. This experiment comparie to subsample fermentation method, encoding standard (TTC) methed, kit (ECLIPSE50) method and paper method: preparation 40 samples ,each sample have five parallel and use the five methods detect which sensitivity. positive rates subsample fermentation method 22.5%, encoding standard (TTC) 25%, this method 23.75%, kit (ECLIPSE50) 26.25%, paper 32.5%.The studiing method sensitivity between subsample fermentation and kit method ,the sensitivity have reliability. Sensitivity of subsample fermentation method low, no do- ubtful samples too more of TTC method, even operation too complex ,bacterium liqu- id density hard to controlling. Commercialization of kit and paper methods oper- ation are simple but the cost very expensive, they can use in laboratory, not easy to general nursery and milk station.This paper aims at developing the detection method of antibiotic in milk by Bacillus stearoth- ermophilus based on exisiting detection method, and set up a simple rapid and sens- itive antibiotic detection method which can be applied widely. This method can arrive the detection limit and detection time and the detection cost decrease largely . So the method is available.