Biodegradation of xanthan by newly isolated Cellulomonas sp. LX, releasing elicitor-active xantho-oligosaccharides-induced phytoalexin synthesis in soybean cotyledons

A Cellulomonas sp. LX newly isolated from soil samples could degrade the extracellular polysaccharide (xanthan) of Xanthomonas campestris. Such degradation was inhibited by glucose addition. Xanthan-degrading enzyme activity was found in the culture supernatant when Cellulomonas sp. LX was grown in the medium with xanthan as carbon source. The optimal pH and temperature for the xanthan-degrading reaction was 6.0 and 40 °C, respectively. The bioactivity of the xantho-oligosaccharide was examined with the soybean cotyledon bioassay and found it was an active elicitor.