Abstract
Little is known about the bacteria living inside the plants of the Little Rann of Kutch, a hypersaline desert in western India, and its culturable microbiota has barely been described at all. Imidacloprid is sprayed heavily on the farmland around the Rann, it lingers in soil, and it turns up in groundwater, so bacteria that can both survive salt and act on the compound are worth looking for. We collected roots of nine halophyte species at four sites inside the Wild Ass Sanctuary, surface sterilized and macerated them, then enriched the macerates in yeast extract mannitol broth carrying 5% (w/v) sodium chloride at pH 9. Eleven isolates came out of this. Each was described morphologically and biochemically, and partial 16S rRNA gene sequences were matched against public databases. Tolerance was tested on agar amended with a commercial imidacloprid formulation, and supernatants from the four best growers went through reversed-phase high-performance liquid chromatography. The isolates fell into Bacillus, Brevibacillus and Pseudomonas. Eight of the eleven grew on the amended medium; Bacillus aryabhattai 10AY and Bacillus nealsonii 5 grew best of all. In every one of the four treated cultures the peak that dominates the untreated control had gone, and peaks that were absent or minor in the control had appeared, which points to transformation of the parent compound. These salt-tolerant endophytes deserve a proper quantitative look as candidates for clearing neonicotinoid residues from saline farmland.