Degradation of nitrate by enterobacteria during silage fermentation of grass.

Abstract

Enterobacteria were isolated from grass and from grass ensiled in laboratory silos. Strains isolated from grass belonged mainly to the Erwinia herbicola group. After ensiling, the numbers of these bacteria diminished and Escherichia coli, Hafnia alvei and Klebsiella pneumoniae became the predominant bacteria in the respective experiments. Several strains, isolated either from grass or silage, were tested for their action on nitrate degradation by adding them to grass prior to ensiling. The isolates from grass did not affect nitrate degradation, whereas those from silage increased the rate of nitrate degradation and gave higher transient concn of nitrite and nitric oxide. Results showed no direct relationship between the total number of enterobacteria on grass and its ensilability. The numbers of enterobacteria on grass that developed after ensiling were 2 orders of magnitude lower than the total number of enterobacteria originally present on the grass. (Abstract retrieved from CAB Abstracts by CABI’s permission)