Optimization of Process Parameters for Siderophore Production Under Solid State Fermentation Using Polystyrene Beads as Inert Support

Abstract

Kuttanad, commonly called the rice bowl of Kerala, is noted for its paddy cultivation well below sea level. Decrease in micro and macro nutrients is a common phenomenon in all agricultural lands and the micro-biota plays a major role in maintaining soil fertility of agrarian regions. Iron is one of the most common limiting trace elements in nature which is essential for the growth and metabolism of almost all living organisms. Deficiency of iron is primarily due to its poor solubility. Bacteria secrete iron chelating agents known as siderophores to absorb iron, which promotes plant growth. In the present study, soil and water samples from Kuttanad were screened for siderophore producing bacteria. Ten siderophore producing bacteria were isolated from the soil and water environments by primary screening. Secondary screening using Chrome Azurol Sulphonate agar was done to confirm siderophore producers. A <i>Pseudomonas</i> strain isolated from the soil was selected for siderophore production under solid state fermentation using polystyrene beads as inert support. Process parameters of the fermentation process along with additional carbon, nitrogen and amino acid sources were optimized so as to increase the production of siderophores. Succinate medium of pH 8, incubation temperature of 35^oC and incubation time of 48 hours were proved optimum for siderophore production. 0.5% v/w glycerol, 0.5% w/w ammonium chloride and 2.5 % w/w L-asparagine were the carbon, nitrogen and amino acid sources which gave maximum siderophore production respectively. This is the first study of its kind and has tremendous potential for further research.