An Improved Method for the Enumeration of Denitrifying Bacteria
1973
Focht, D. D. | Joseph, H.
An improved method for enumerating denitrifying bacteria from soil by use of the most-probable-number method is outlined. Difco nitrate broth was used, and culture tubes near the dilutions to extinction were analyzed for the disappearance of nitrate-nitrite. The distinction between denitrifying and nondenitrifying bacteria was clearly defined and thus minimized visual subjective errors. Earlier methods which assumed that a pH increase was due solely to denitrification were shown to be ambiguous by comparison between culture tubes for nitratenitrite disappearance; 1 out of every 4 tubes compared gave an erroneous reading for dentirification. The distribution of denitrifying bacteria within two different soil profiles showed a definite logarithmic decrease in numbers with depth.
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