The nucleotide acids in both conserved sequences are mutative, even the length of the spacer is variable, and they both brought troubles in determining Escherichia coli promoter with computer.

• 由于保守序列中的碱基是可变的,而且间隔碱基的长度也是可变,这给大肠杆菌启动子的计算机识别带来了难度。