Optimization of Cell Protectants, Adjuvant and Additives to Develop Liquid Formulation of Azospirillum
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Date
2017-09
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University of Agricultural Science, Dharwad
Abstract
An effort was made to optimize the additives, adjuvant and surfactant for the growth and shelf life of liquid formulations of Azospirillum ACD-15 at the Institute of Organic Farming, University of Agricultural Sciences, Dharwad during 2014-15.
Sodium malate broth was amended with additives such as polyethylene glycol at 0.5 and 1.0 per cent, trehalose at 5 and 10 mM and glycerol at 5 and 10 mM. Adjuvant like gum arabica at 0.15 and 0.30 per cent; surfactant like polysorbate - 20 at 125 and 250 ppm. A total of 32 combinations of formulations were developed and evaluated for their ability to support growth and higher populations of Azospirillum ACD-15 over a period of 72 h. Based on population dynamics only nine formulations with population more than 9.6 x 109 CFU ml-1 after 72 h were chosen for further incubation studies. These nine formulations were kept for shelf life study over a period of six months at both ambient and refrigerated conditions. Among them, formulation 2 under both conditions was found to be far superior to others in terms of the population of Azospirillum ACD-15 at all stages over 180 days of incubation. This formulation recorded the highest populations in terms of the most probable number estimation of Azospirillum ACD-15 under ambient condition (6.18 x 106 cells ml-1) and under refrigerated condition (1.07 x 106 cells ml-1). The population was also assessed by direct plate count technique with values of 1.58 x 109 cells ml-1 at ambient condition and 7.0 x 107cells ml-1 at refrigerated condition.
In the present study, the cost involved in the production of this efficient formulation 2 was 376 litre-1 and 58 per cent of this cost was on one amendment trehalose (additive) alone. The results from this study clearly indicated that the liquid formulation of Azospirillum ACD – 15 was better in terms of viable population and shelf life compared to lignite formulation.