TABLE 1.

MPN values of Fe(III)-reducing microbes and total counts of DAPI-stained microbes obtained from acidic sediments^a

Metabolic type	Medium	pH	MPN (g [wet wt] of sediment−1)b
Glucose-utilizing Fe(III) reducer	Fe-TSB	2.3	4 × 103 (8.6 × 102–1.9 × 104)
Glucose-utilizing Fe(III) reducer	FePPi	6.7	2.3 × 103 (4.9 × 102–1.1 × 104)
H2-utilizing Fe(III) reducer	FePPi	6.7	<3
Acetate-utilizing Fe(III) reducer	FePPi	6.7	<3
Total DAPI-stained  microbes	NAc	NA	7.2 × 105 (5.8 × 105–8.6 × 105)

^aMPN dilutions were incubated in three replicates at 15°C for 9 months. 

^bValues in parentheses represent the ranges of the MPN values within 95% certainty. 

^cNA, not applicable.