Isolation and characterization of nitrogen-fixing moderate halophilic bacteria from saline soils of Egypt

✍ Scribed by Dr. H. H. Zahran; M. S. Ahmad; E. A. Afkar

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 468 KB
• Volume: 35
• Category: Article
• ISSN: 0233-111X
• DOI: 10.1002/jobm.3620350412

✦ Synopsis

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.