TABLE 2.

Influence of duration of laboratory incubation and naphthalene on survival of inoculated recipient bacteria and on frequency of conjugation between the native sediment microbial community (10 g of sediment) and recipient strain Cg21.CR inoculated at 10⁹ cells/g

Incubation time (days)	Recipient recoverya and transconjugant plasmid type
	No added naphthalene			Naphthalene added
	%R	RFLPa	RFLPb	%R	RFLPa	RFLPb
4	12	0	0	7.3	0	0
6	2.5	0	0	5.2	0	0
8	1.5	0	0	0.8	0	0
11	0.2	0	0	0.2	0	0
14	0.09	0	0	0.04	11	8

^a%R, percent recipient recovery. Percent of initial inoculum growing from a 2-g subsample diluted and plated in duplicate on Stanier's mineral salts medium supplemented with 300 μg of rifampin per ml, 100 μg of cycloheximide per ml, and 0.1% pyruvate.