Abstract

Nitrogen fixation is considered as a significant biological process, which is important in agricultural and environmental implications. Herein denitrifying bacteria from Bahr Al-Milh Salt Lake, Karbala, Iraq, was reported using molecular and phenotypical characteristics. Samples were collected from eastern parts of the Bahr Al-Milh. The strains were grown in different saline concentrations of nutrient broth (2.5–22.5%). 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. 218 strains were isolated, 76.6% of which were nitrate reductase and 25.5% nitrate-nitrite reductase (NiR) positive strains. 68% slightly and 32% moderately halophilic bacteria were found. Isolates with nitrite reduction activity belonged to five genera including Bacillus, Halobacillus, Idiomarina, Oceanobacillus, and Virgibacillus. The isolates with the ability of producing nitrate-NiR consisted of bacteria in genera Halobacillus and Halomonas. Apart from industrial and biotechnological applications, the present information might be useful to fertilize the 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. To the best of our knowledge, this is the first microbiological study on halophilic bacteria from Bahr Al-Milh Salt Lake.

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