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Isolation and characterization of nitrogen‐fixing moderate halophilic bacteria from saline soils of Egypt
Author(s) -
Zahran H. H.,
Ahmad M. S.,
Afkar E. A.
Publication year - 1995
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.3620350412
Subject(s) - bacteria , mannitol , nitrogen fixation , microbiology and biotechnology , biology , saline , spore , food science , bacillus (shape) , nitrogenase , chemistry , botany , biochemistry , genetics , endocrinology
Twenty out of 400 isolates of bacteria mainly from salt marshes and saline soils of Egypt were successfully grown on mannitol N‐free medium. The nitrogen‐fixing activity was then demonstrated for the twenty isolates in modified Stanier'S medium using the acetylene reduction assay. All of them possessed appreciable nitrogenase activity (acetylene reduction) under non‐saline conditions; however, at 5% NaCl only 60% of the isolates exhibited a high rate of this activity and 25% were completely negative under these conditions. The bacterial isolates grew well in Stanier'S medium; nevertheless, growth of the majority of isolates was reduced by about 30‐80% in the same medium containing 5% NaCl. Cellulolytic activity was detected in 60% of the twenty strains, amylolytic in 45%, and pectinolytic in 10% of the isolates. The bacterial isolates showed also enzymatic activity under saline conditions (5% NaCl). The preliminary identification indicated that six isolates were Gram positive spore‐forming bacteria of the genus Bacillus , the others were Gram negative rods which remain to be identified.