Decoding multifarious role of cow dung bacteria in mobilization of zinc fractions along with growth promotion of C. annuum L.

Zinc is one of the micronutrients, required by all types of crops. About 10–100ppm of zinc is present in soil which is generally immobile. The cow dung sustains all life and being practice since aeons. Exploitation of cow dung bacteria can mobilize nutrients besides contributing in sustainable agriculture. Therefore, to examine mobilization of Zn, cow dung is used as a source of bacteria. The objectives of the present study were to isolate an array of bacteria from cow dung and to characterize them for their Zn (ZnO and ZnCO(3)) mobilization ability in addition to establish the optimum conditions for dissolution of zinc. A total of seventy bacterial isolates have been screened for Zn mobilization. Out of which most potent (CDK15 and CDK25) were selected to study the effect of various parameters viz. pH, temperature and concentration of Zn. These parameters were assessed qualitatively in diverse growth medium and quantitatively using Atomic absorption spectroscopy. Optimum pH and temperature for mobilization was recorded at pH 5 (ZnO) and 37 °C (ZnCO(3)) by CDK25, whereas, optimum zinc concentration for mobilization was recorded at 0.05% (ZnO) by CDK15. Maximum amount of Zn solubilized was recorded by CDK25 in ZnO (20ppm). Considering the abilities of most potent bacterial isolates with reference to P-mobilization and growth promoting traits, pot culture assay of C. annuum L. was carried out. The findings of which conclude that, bacterium CDK25 (Bacillus megaterium) could be exploited for factors viz. nutrient management of Zn, growth promoting agent, and Zn augmentation in soil.