Salt tolerant Gordonia sp for cultivation in saline soils - Pathogen turns Protector

Agriculture field is going to get a revolutionary breakthrough from identification of newer strains of salt tolerant bacteria. Of the available irrigated land, almost ten percent is saline in nature thereby causing difficulty to cultivate. Loss of agricultural land is detrimental to the food security. The process of sainization is shrinking the world's cultivated area by 1-2 percent each year. In the arid and semi arid regions of the world, the figures can be as high as 25 percent.

Mineral Salts are washed away from rivers to the agricultural land and can cause water logging. This in turn cause mineral salts to be accumulated around the roots thus decreasing the ability of the plant to absorb water from soil. The damage is profound in arid and semi arid regions. Therefore researchers have been trying to identify and develop new strains of microbes for rejuvenating saline soils for agriculture.

Gordonia sp, a coryne form of bacteria has been found to yield promising results. The salt tolerant diazotrophic bacteria genus is common in nature and comprises around 33 strains. The bacteria isolated from the rhizospheric soil have been found to have Plant Growth Promoting (PGP) feature. Their role in nitrogen fixing on pearl millet has been proved at the Haryana Agricultural University.

The strain identification was carried out by isolating and analyzing the 16s rRNA sequence. Investigation on nitrogen fixing ability of Gordonia sp was determined with the nifH gene amplification using primers. nifH gene is responsible for nitrogen fixation in rhizobial species. Bacterial culture JPA 2 of Gordonia sp was found by researchers to be different morphologically as well as biochemically from other strains of Gordonia. Further biochemical tests such as acetylene reduction assay confirmed the Gordonia sp ability to fix nitrogen without doubt.

Use of bioinformatic tools such as BLAST algorithm has been found to be helpful in identification of similar RNA sequences for strain characterization.

Since the newly found Gordonia is salt tolerant upto 6% NaCl, this can be used as bioinoculant especially in plants growing in salt soil conditions. Use of Gordonia sp as bioinoculants is promising. Other species such as Azospirillum, Bacillus and Enterobacter strains are used as bioinoculants to improve plant growth. Experiments using Gordonia strain as bioinoculant in ZeaMays have been successful.

Gordonia sp is an opportunistic pathogen requiring improvement of strain before it can be used as a bioinoculant for nitrogen fixation. Strain improvement and further scaling up of Gordonia sp culture can reclaim the lost agricultural lands to guarantee food security in future.

About Author / Additional Info:
1. Monika Kayasth, Varun Kumar, Rajesh Gera; Gordonia sp.: a salt tolerant bacterial inoculant for growth promotion of pearl millet under saline soil conditions; 3 Biotech
DOI 10.1007/s13205-013-0178-5

2. Arenskötter M, Bröker. D and Steinbüchel. A; Biology of the Metabolically Diverse Genus Gordonia; Applied and Environmental Biology; June 2004 vol. 70 no. 6 3195-3204