TABLE 2.

Colony hybridization of phenanthrene-degrading isolates to DNA probes constructed from genes encoding PAH-catabolic pathways

Sample date	Total no. of isolates	No. of isolates weakly hybridizing to:
		nahAaAb probeb	pY3-E16b
May 1992	25	0	3 (12)c
June 1992	26	0	6 (23)
May 1993	38	0	10 (26)
June 1993	41	0	0
March 1994	70	8 (11)	4 (6)
June 1994	237	3 (1)	28 (12)

^aThe nahAaAb probe is a 2.5-kb DNA probe encoding reductase_nap and ferredoxin_nap of the naphthalene dioxygenase gene. 

^bpY3-E16 is a 16-kb DNA probe encoding the upper pathway for phenanthrene, naphthalene, and fluorene degradation and includes nahAaAb. 

^cThe values in parentheses are percentages.