题目

在以尿素为唯一氮源的培养基中加入酚红指示剂的目的是（　　）                  A．筛选出能分解尿素的细菌                                                                    B．培养基中缺乏酚红指示剂作细菌的营养                                               C．对分离的菌种作进一步的鉴定                                                             D．如指示剂变蓝就能准确认定该菌能分解尿素                                               答案：解：尿素分解菌可以产生脲酶将尿素分解分解为氨，使pH升高，培养基中进入酚红指示剂后，氨可以使指示剂呈红色，据此可以用酚红指示剂鉴别尿素分解菌．                                                     故选：C．                                                                                         

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