从农家土厕粪土中筛选培育出一株脲酶高产菌株，经中国科学院微生物研究所检测鉴定定名为肿大地杆菌，已被中国科学院微生物菌种保藏中心收藏(As1.2690)。该菌株对人畜无致病性，经强化培养条件后每克湿菌产脲酶279.13U。提取纯化的菌体脲酶经测定其分子量为257000，等电点3.40，Km值为0.0403mol·L-1，最大反应速度(Vmax)为3.336μmol·min-1，最适pH7.50，最适反应温度55℃，对热有较高的耐受能力。此脲酶生产优良菌株的选育成功及制得的菌体脲酶有良好的应用前景。%A new strain which is rich in urease has been screened frompeasant family muck. It is named terrabacter tumescens by the Institute of Microbilogy, the China Academy of Scicences, and it is stored by the China General Microbiological Culture Collection Center(No.As1.2690). The strain is not pathogenic.The yield of the enzyme was as high as 279.13 U/g of wet bacteria. The relative molecular weight of the enzyme was determined to be 257 000 by S DS-PAGE. The isoelectric point(pI)was 3.40 as judged by isoelectric focusing experiments. In EDTA buffer, the value of Km was 0.040 3 mol·L-1, the V max was 3.336 μmol·min-1. The optimal pH was 7.50. The optimal temperature was 55℃. These properties of urease have shown a bright futur in its application.
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