Abstract
Three soils with different Electrolytic Conductivity (EC) from the former Lake Texcoco (soil with low EC 1.2 dS·m-1, medium with EC 83.1 - 107.8 dS·m-1, and high with EC 137.3 - 152.5 dS•m-1) were used to isolate nitrogen-fixing bacterial strains through enrichment cultures in nitrogen-free media. The medium and high EC in the soil affected negatively the nitrogen-fixing activity, which was generally ten times lower compared to the activity in the soil with low EC. Twenty-one bacterial strains were isolated, identified and characterized for their nitrogen fixation capacity. The diazotrophic genetic potential of all isolates was confirmed by amplification and sequencing of partial nifH and nifD genes and diazotrophic activity quantified by the acetylene reduction assay. Azospirillum brasilense, and several species of Paenibacillus (P. fujiensis, P. durus, P. borealis, P. graminis, P. massiliensis and P. wynnii) were identified. Isolates belonging to the Paenibacillus genus were found in the three soils. Paenibacillus fujiensis and P. durus showed a high nitrogenase activity. The phylograms based on nifH and nifD gene sequences were consistent with 16S rRNA gene phylogeny.
Highlights
Saline soils or solonchaks cover between 260 million and 340 million ha [1] [2]
Saline soils are of particular interest as they allow investigating the effect of high salt contents on microbial activity in a natural environment [6]-[9]
Halotolerant strains of Bacillus and Paenibacillus were previously isolated from salt mining soils of Russia
Summary
Saline soils or solonchaks cover between 260 million and 340 million ha [1] [2]. How to cite this paper: Navarro-Noya, Y.E., Luna-Guido, M. and Dendooven, L. (2016) Cultivable Nitrogen Fixing Bacteria from Extremely Alkaline-Saline Soils. Ties, such as irrigation and excessive use of fertilizer, have increased salt contents in important agriculture production areas affecting soil processes and limiting crop production. Excessive amounts of salts often result in poor soil structure and affect chemical and biological processes [3]-[6]. Saline soils are of particular interest as they allow investigating the effect of high salt contents on microbial activity in a natural environment [6]-[9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
