Rheological behaviour and yield characterization of gum from local isolates: Xanthomonas hortorum pv. pelargonii and Xanthomonas axonopodis pv. begonia

Abstract

Xanthan production capacity of local isolates X. hortorum pv. pelargonii and X. axonopodis pv. begonia were investigated by systematically changing fermentation conditions. Optimum yields were found as 11.19 g/L, 9.72 g/L and 9.65 g/L and for standard isolate X. campestris DSM 19000, X. hortorum pv. pelargonii and X. axonopodis pv. begonia, respectively. Optimum agitation rate and inoculum volume were found as 180 rpm and 5%. Moreover, better gel forming and thickening properties were obtained for xanthan gum from local isolates. Higher K value was observed for gum solutions of the local isolates at all concentration when Ostwald de Waele model was used. Activation energies changed between 4.85 and 25.43 kJ/mol and it is the highest for gum from standard isolate. Moreover, K’ and K” values obtained from dynamic rheological analysis were higher for the local isolates than that of standard isolate. The results confirmed that the local isolates appeared to be suitable microorganisms for xanthan gum production.