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The objective of this study is to propose a more accurate and faster MTT 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide colorimetric assay (MCA) for quantitative measurement of polypeptide bacteriocins in solutions with nisin as an example. After an initial incubation of nisin and indicator bacterium Micrococcus luteus NCIB 8166 in tubes, MTT was added for another incubation period. After that, nisin was quantified by estimating the number of viable bacteria based on measuring the amount of purple formazan produced by cleavage of yellow tetrazolium salt MTT. Then MCA was compared to a standard agar diffusion assay (ADA). The results suggested a high correlation coefficient (r2=0.975±0.004) between optical density (OD) and the inhibitory effect of nisin on a bacterial strain Micrococcus luteus NCIB 8166 at a range of 0.125~32 IU/ml. The MCA described in this study was very quick. Quantification of nisin took only 7~8 h and the detection limit was at the level of 0.125 IU/ml when compared to 12 IU/ml and 24~28 h for ADA. The MCA provides an accurate and rapid method for quantifi-cation of nisin in solutions and is expected to be used for quantification of other antimicrobial substances. 相似文献
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目的::通过对生物乳酸钙豆腐的保质观察及乳酸链球菌素(Nisin)、脱氢乙酸钠对生物乳酸钙充填豆腐保质期的影响,探索生物乳酸钙充填豆腐的保质技术。方法:在点脑时在豆浆中加入Nisin、脱氢乙酸钠,同时做空白对照,在不同的保藏条件下,以菌落总数、大肠菌群和感官评价作为评价指标观察豆腐品质变化。结果:空白组和添加脱氢乙酸钠组杀菌后在37℃和常温下很快变质,冷藏条件下可保藏半年;添加Nisin组杀菌后在37℃恒温条件下可存放1周,常温下可保藏达一个月,冷藏条件下可保藏半年,且豆腐弹性较好,色泽均匀有光泽,口感细腻爽滑。结论:生物乳酸钙充填豆腐在冷藏条件下可保藏半年,Nisin对延长其货架期有明显的效果。 相似文献
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