Denitrification in Flexibacter canadensis: A gliding soil bacterium able to reduce nitrous oxide in the presence of sulfide and acetylene.

摘要

Denitrification was studied in pure cultures of Flexibacter canadensis, a Gram-negative gliding bacterium found in soil. Flexibacter canadensis was capable of complete denitrification. Sulfide alleviated the acetylene {dollar}rm(Csb2Hsb2){dollar} inhibition of nitrous oxide (N{dollar}sb2{dollar}O) reduction by this organism.; The properties of the gliding bacterium, Is-ll, were reexamined. Is-ll was previously isolated from soil because of its ability to denitrify and reduce N{dollar}sb2{dollar}O in the presence of normally inhibitory concentrations of {dollar}rm Csb2Hsb2.{dollar} Although originally tentatively identified as a Cytophaga sp., extensive morphological, physiological, and biochemical tests, as well as G + C analysis, and DNA hybridization studies now indicate that soil isolate Is-ll is a strain of F. canadensis.; The sulfide relief of {dollar}rm Csb2Hsb2{dollar} inhibition of N{dollar}sb2{dollar}O reduction by F. canadensis was examined. Under these conditions, N{dollar}sb2{dollar}O reduction coincided with a decrease in liquid phase dissolved sulfide concentration. The fate of this sulfide is unknown. Both biological and chemical factors appear to contribute to the sulfide relief of {dollar}rm Csb2Hsb2{dollar} inhibition in pure cultures of F. canadensis. However, the mechanism remains to be elucidated.; Nitrous oxide reductase of F. canadensis was located in the membrane fraction of cell-free extracts from this bacterium. Nickel, rather than copper, stimulated growth and N{dollar}sb2{dollar}O reduction in N{dollar}sb2{dollar}O-dependent anaerobic growth of F. canadensis in the presence of EDTA.; An ecological study combining most probable number techniques and bacteriophage analysis indicated that F. canadensis is commonly found in soils and sediments.