Cassava Starch Hydrolysate as Sustainable Carbon Source for Exopolysaccharide Production by Lactobacillus Plantarum

Abstract

Cassava starch hydrolysate (CSH) proved to be a potential alternative for EPS production by L. plantarum. Enzymatic hydrolysis of 9% (w/v) cassava starch resulted in nearly 85% conversion of it to the sugars which can be directly assimilated by the bacterium. Culture medium (pH 7.3) having cassava sugar (40 g/L), yeast extract (40 g/L) and ammonium sulphate (5.5 g/L) along with tween 80 (4 g/L), calcium chloride (10 mM) and hydrogen peroxide (3 mM) found to be very effective for EPS production. After the double step ethanol precipitation, a maximum titer of 6.5 ± 0.5 g/L crude EPS was obtained in static flask cultures incubated at 37 °C with 2% v/v inoculum and it was 4.4 ± 0.5 g/L with the control medium having lactose as carbon source. Thermal stability and molecular weight were remained unchanged irrespective of the carbon source used. This is the first report on EPS production by a Lactobacilli using CSH as raw material.