Abstract:

In order to study the xanthan gum secreted by Xanthomonas axonopodis FJAT-10151, The growth curve of FJAT-10151 was determined by the turbidimetric method. The yield of xanthan gum was determined by the dry-weighing method. The content of pyruvic acid was determined by the 2,4-dinitrobenzene hydrazine chromogenic method. The secretion of xanthan gum from X. axonopodis was studied by SEM and TEM. The result showed that the logarithmic phase and stable phase of FJAT-10151 was 0-26 h and 26-72 h, respectively. FJAT-10151 was a short rod of 2 μm long with 7.9 μm of flagellum on the ends, and formed a thick capsule outside, and many bacteria together with xanthan gum. Xanthan gum had flake and filamentous forms, and gathered or wrapped around FJAT-10151 surface. The yield of xanthan gum increased with the extension of fermentation time. The yield of xanthan gum and pyruvic acid reached the highest at the fermentation time of 72 h. We could obtain high quality of xanthan gum at the fermentation time of 72 h.

Key words: Xanthomonas axonopodis, xanthan gum, microscopic observation, pyruvic acid