Studies On The Xanthan's Degradation, It's Degradation Products' Structural Analysis And Biological Activities

Oligosaccharides attract many researchers'interest due to their extraordinarybiological activities. Xanthan gum is the most important microbial polysaccharidecommercially, however, its degradation products'biological activities is not reportedyet.A strain tentatively identified as Cellulomonas sp. was isolated from soilsamples and shown to degrade xanthan gum. The xanthan-degrading enzyme waspartially purified by salting out and ion-exchange chromatography. The enzyme'sactivity was also detected and found that it is not thermostable. The optimaltemperature is at 30-40℃　and　pH　optimum　is　5.0-7.0. The enzyme is highspecificity on xanthan. There is no effect of the tested metal ions on enzyme activitybut the inhibition of EDTA on enzyme could be complemented by addition of Ca2+partially.The composition of xanthan gum's enzymic degradation products -oligoxanthan was analyzedby HPAEC-PAD and MALDI-TOF-MS, and the resultsshowed that xanthangum's most basic enzymic degradation products werepentasaccharide units. Hence, the enzyme's hydrolysis reaction sites were confirmed.Oligoxanthan's biological activities were also explored. The results showed thatoligoxanthan had many functions: inhibition activity on the growth of fungi,anti-virus activity, elicitor activity in plant, and free radical scavenging activity.However, it could not inhibit the growth of bacteria.