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Isolation and characterization of nitrogen-fixing moderate halophilic bacteria from saline soils of Egypt. J Basic Microbiol 1995. [DOI: 10.1002/jobm.3620350412] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
The majority of
Azotobacter chroococcum
strains in a collection obtained from Alberta soils were absolutely dependent on Na
+
for growth. Two strains from the American Type Culture Collection also were either Na
+
dependent or were stimulated by Na
+
. Optimal growth required 0.8 mM Na
+
and was limited at 0.2 to 0.35 mM Na
+
. Growth promoted by 0.8 mM Na
+
was inhibited by Rb
+
> K
+
>> NH
4
+
but was not affected by Li
+
. Growth inhibition by Rb
+
and K
+
was overcome by increasing the Na
+
concentration present in the medium. Excellent growth in media containing limiting Na
+
was obtained when 25 mM Li
+
or 25 mM Mg
2+
was added. Li
+
was significantly more effective in replacing Na
+
than was Mg
2+
. Na
+
was required for growth on all C sources (glucose, sucrose, melibiose, and mannitol) and N sources (N
2
, NH
4
+
, and NO
3
−
) and was required throughout the pH range of growth. Cells suspended in Na
+
-deficient medium or in distilled water did not appear to lyse or lose viability.
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Affiliation(s)
- W J Page
- Department of Microbiology, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
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