Converting Fumaric Acid to L-Malic Acid by Mutated Aspergillus Wentii

The aspergillus wentti which had been treated with 60Co was selected as the strain to convert fumaric acid to L-malic acid.The main factors that influenced the results of conversion were investigated.The experimental results showed that the optimal fermentating conditions for shake flask were:original concentration of fumaric acid,11%～12%;fermenting time,96～106 h;pH 6.5～7.5;temperature 30℃.Under suitable conditions,the average conversion rate of fumaric acid was 83.51%,and the L-malic acid yield was 11%.The average conversion rate of fumaric acid converted by mutated aspergillus wentii was increased by 10% compared with that converted by the original strain,and the time for culture of strain was shortened from 3 days to 1 day.