TABLE 1.

Results of direct and plate count analyses^a

Dilutionb	AODC (106 cells/ml)	R2A count (106 CFU/ml)	% Culturability on R2A	SM count (106 CFU/ml)	% Culturability on SM	Ratio of SM count to R2A count
100	22.0 ± 10.0*	0.7 ± 0.4*	4.5*	0.6 ± 0.2*	3.2*	1.1
10−1	13.0 ± 8.6*	0.7 ± 0.5*	5.1*	1.2 ± 0.7*	10.0*	2.1
10−2	24.0 ± 14.0*	1.4 ± 1.2*	7.5*	2.2 ± 1.2*	13.3*	2.2
10−3	30.0 ± 15.0*	4.6 ± 2.7*	14.3*†	5.2 ± 1.7*†	18.3*	1.3
10−4	39.0 ± 2.8*†	5.6 ± 1.7*	14.4*†	5.9 ± 1.6*†	15.3*	1.2
10−5	73.0 ± 19.0†	23.6 ± 11.0*†	32.4†	12.4 ± 3.8*†	18.0*	0.6
10−6	110.0 ± 9.0‡	204.0 ± 1.9‡c	100.0†d	58.1 ± 83.2†	44.1*	0.8

^aEach value is the average ± 1 standard deviation (when listed). 

^bDilution refers to the original dilution used as the inoculum for each regrown community. Each superscript symbol denotes a significantly different group of communities determined as described in the text; significance was not evaluated for the ratio of SM counts to R2A counts. 

^cOn R2A plates spread from two of the three 10⁻⁶ treatment flasks, colony growth was too extensive and data were recorded as too numerous to count. The value presented here, and used in all further calculations, was established by assuming a count of 300 CFU on the most-dilute plate, for each of those replica flasks, and averaging this with the counts obtained for the remaining flask. 

^dIn the communities regrown from the 10⁻⁶ dilution, growth on R2A exceeded the AODC and so a culturability of 100% was inferred.