Objectives: Nitrogen fixation is considered as a significant biological process, which is important in agricultural and environmental implications. Herein we reported denitrifying bacteria from Bahr Al-Milh Salt Lake, Karbala, Iraq, using molecular and phenotypical characteristics.
Material and Methods: Samples were collected from eastern parts of the Bahr Al-Milh. The strains were grown in different saline concentrations of nutrient broth (2.5% to 22.5%). Nitrate and Nitrite reduction activities were assessed for all the isolates. Molecular analysis was performed by BLAST alignment and MEGA7 software. The 16S rRNA sequences of newly found strains were submitted in the GenBank database.
Results: Two hundreds and eighteen strains were isolated, 76.6% of which were nitrate reductase and 25.5% nitrate-nitrite reductase positive strains. 68% slightly and 32% moderately halophilic bacteria were found. Isolates with nitrite reduction activity belonged to five genera including Bacillus, Halobacillus, Virgibacillus, Oceanobacillus and Idiomarina. The isolates with the ability of producing nitrate-nitrite reductase consisted of bacteria in genera Halomonas and Halobacillus.
Conclusions: Apart from industrial and biotechnological applications, the present information might be useful in order to fertilize saline soil for agricultural aims. The isolated strains could be considered as a source of halotolerant enzymes in agriculture and environmental implications in hypersaline areas.
Key words: halophiles; nitrate reductase; nitrite reductase; screening