PURPOSE: To obtain a new rRNA gene useful for the detection of Pseudomonas cepacia KK01 strain active on decomposing phenol, trichloroethylene, etc.

CONSTITUTION: This nucleic acid fragment is a 16S rRNA gene of Pseudomonas cepacia KK01 strain having a base sequence of the formula. An extension reaction is carried out by using a nucleic acid fragment of 10-50 bases originated from the nucleic acid shown by the gene sequence as a primer and the P. cepacia KK01 strain is detected from the extension reaction product. The rRNA base sequences of various known Gram-negative bacteria are compared, a common sequence region is estimated, a primer DNA is synthesized from the region, the fragment of about 1,100 bases in the 16S rRNA gene in the DNA of P. cepacia KK01 strain is amplified by PCR method and the product is cloned to the HincII cutting site of plasmid pUC119. The whole length of the 16S rRNA gene is cloned by the gene fragment and the base sequence is determined by subcloning to obtain the objective fragment.