Optimization of medium compositions and functional characteristics of exopolysaccharide from Paenibacillus polymyxa ATCC 824

Abstract

Paenibacillus polymyxa ATCC 824 can produce exopolysaccharides (EPS) as non-toxic biomaterials that is safe for plant and soil health. The cells of P. polymxya ATCC 842 known as a good plant growth promoting bacteria. Unfortunately EPS as biopolymers that contributed to soil health. Nowadays, it's showing interest in the production, characterization, and application of EPS derived from various microorganisms. Because of their unique structures, plant growth-promoting bacteria polysaccharides have unique properties and applications in agriculture. This work aims to develop production medium for high cell mass cultivation of P. polymxya ATCC 842 co-currently fort production of EPS. The main medium component such as sucrose, yeast extract and K2HPO4 were selected as variables and statistically optimized based on Box-Behnken design in shake flask levels. The optimal medium composition by RSM composed of (g/L): sucrose, 30; yeast extract, 30; K2HPO4, 5.72; NH2NO4, 5; KH2PO4, 1.9 and MgSO4, 0.5. The growth in the optimized medium showing the cell mass was increased 20.36 g L −1 about 7.51-fold higher co-currently increased EPS production about 6.71-fold higher (16.46 gL −1)than the unoptimized medium after 36 h of cultivation. The model was significant and subsequently validated through the growth kinetics studies showing that the optimized medium have better growth of P. polymyxa ATCC 842 with a specific growth rate of 1.397 h −1 and EPS productivity about 0.68gL −1 h −1. Furthermore, HPLC analysis showing that EPS is composed monomer of fructose and glucose. Meanwhile, FTIR analysis showed the presence of hydroxyl, carboxyl groups, and glycosidic linkages which showed the composition of the polysaccharide bound by α-(1 → 6). The SEM analysis showed EPS appears as a homogenous spherical with irregular porosity for high water holding capacity of the soil. Based on these findings, EPS produced by Paenibacillus polymyxa has a variety of useful properties that make it suitable for use in agriculture.