1887

Abstract

sp. nov. was isolated from slightly saline soils of Western Canada, where strains of this species accounted for ≤5% of the aerobic nitrogen-fixing isolates. Also, one isolate was obtained from a saline Egyptian soil. These bacteria shared many physiological traits with , but were absolutely dependent on Na ions for growth and frequently used melibiose as a carbon and energy source. Aerobically grown cells were melanized dark brown to black; the cells were large, gram negative, oval with pointed ends, and motile by means of peritrichous flagella and formed pairs and chains of six to eight cells during active growth. Capsule production was variable. Nitrogen fixation by occurred optimally at 35°C in the presence of molybdate or vanadate ions in a microaerophilic, aeroadaptive manner. The cells were very sensitive to HO and catalase negative. However, a single weak catalase electromorph was observed in cell extracts. This contrasted with a very active catalase represented by multiple electromorphs in . Iron was absolutely required for growth and aeroadaptation. Other growth-promoting substrates included fructose, galactose, glucose, mannitol, starch, and sucrose. Acid was formed from growth-promoting sugars and also from the non-growth-promoting substrates arabinose, cellobiose, lactose, mannose, rhamnose, and xylose. Incubation in the presence of increased NaCl concentrations promoted acidification of the culture to inhibitory levels, and sufficient acid was released from nitrogen-fixing cells in the presence of 1.0 to 1.5% NaCl to solubilize CaCO suspended in solid medium. The cells grew well in marine broth alone, producing an alkaline reaction. An acid reaction was produced both oxidatively and fermentatively in marine broth containing glucose. Nitrate was used in an assimilatory fashion, and there was no evidence of NO- or N formation. The type strain is strain 184 (=ATCC 49674), which was isolated from soils of Alberta, Canada.

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/content/journal/ijsem/10.1099/00207713-41-3-369
1991-07-01
2019-12-12
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