A New Spectrophotometric Method for Quantification of Potassium Solubilized by Bacterial Cultures
Indian Journal of Experimental Biology Vol.52, March 2014, pp. 261-266 A new spectrophotometric method for quantification of potassium solubilized by bacterial cultures Mahendra Vikram Singh Rajawat, Surender Singh & Anil Kumar Saxena* Division of Microbiology, Indian Agricultural Research Institute, New Delhi 110 012, India Received 26 March 2013; revised 8 October 2013 A new spectrophotometric method was developed for the quantification of potassium in the culture broth supernatant of K-solubilizing bacteria. The standard curve of potassium with the new method, which is based on the measurement of cobalt, showed a regression coefficient (R2) of 0.998. The quantification values of potassium obtained with flame photometric method and the newly developed method showed a significant correlation (r) of 0.978. The new method depends on the precipitation of sodium cobaltinitrite with solubilized potassium in liquid medium as potassium sodium cobaltinitrite, which develops bluish green colour by the addition of conc. HCl. The intensity of developed colour can be recorded at 623 nm. This method involves less number of steps, is easy and time saving, and can be used for the reliable estimation of available potassium in culture broth supernatant of K-solubilizing bacteria Keywords: Cobalt nitrite, Flame photometry, K-solubilizing bacteria, Potassium solubilization Bacteria are known to solubilize potassium from methods employ the ability of potassium to precipitate minerals like mica, feldspar, aluminosilicate minerals, sodium cobaltinitrite as sparingly soluble sodium phosphorite, K-rich shale, rock powder, microcline, potassium cobaltinitrite and the subsequent estimation orthoclase, and muscovite1-6. Plate assay based on of one of the constituents of the precipitate.
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