TITLE:
Cultivable Nitrogen Fixing Bacteria from Extremely Alkaline-Saline Soils
AUTHORS:
Yendi E. Navarro-Noya, Marco Luna-Guido, Luc Dendooven
KEYWORDS:
Diazotrophs, Extremophyles, Haloalkaline, Halotolerant, Paenibacillus
JOURNAL NAME:
Advances in Microbiology,
Vol.6 No.6,
May
13,
2016
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.