Table 1.

Average similarity between bacterial and archaeal DGGE profiles from methanogenic microcosms

	Bacterial profiles		Archaeal profiles
Time (days)	Similarity within replicates	Similarity between oil and no-oil treatments	Similarity within replicates	Similarity between oil and no-oil treatments
22	84.7 ± 5.1	79.4 ± 4.5	80.8 ± 5.0	75.1 ± 4.1
302	79.1 ± 7.2*	32.7 ± 4.7*	73.3 ± 3.4*	57.3 ± 1.1*
686	72.8 ± 1.6*	36.9 ± 5.8*	81.1 ± 3.8*	40.3 ± 3.8*

The asterisk indicates a statistically significant difference between oil treated and untreated samples (t-test P < 0.05).