Abstract: The production of xylonic acid from hydrolysates of straw by whole-cell catalysis was investigated with long-term domesticated Gluconobacter oxydans as catalytic strain.The results showed that the catalytic reaction could be inhibited by hydrolysates without detoxication,and the inhibitory effect was more obvious with the increase of concentration.However,it could be counteracted by increasing inoculation quantity and dissolved oxygen.In the shake flask system,with the inoculation amount of 2 g/L and the xylose concentration of hydrolysates more than 100 g/L,the performance of cell catalysis was inhibited seriously,and the yield of xylonic acid and utilization rate of xylose were all lower than 50%.When the inoculation amount increased to 8 g/L,the yield of xylonic acid reached 85.7%.The method of compressed oxygen supply in the sealed aerated stirred tank reactor was investigated,and in 24 h the concentration and yield of xylonic acid reached 103.1 g/L and 93.1%,respectively.And the production rate increased 1.6 folds compared with that of the shaker system when xylose concentration of hydrolysates was 100 g/L and inoculation amount of G.oxydans was 8 g/L.

Key words: xylonic acid, xylose, whole cell catalysis, Glucobater oxydans, straw hydrolysates