Effect of Different Carbon Sources on Succinic Acid Production of Actinobacillus succinogenes and Metabolic Flux Analysis / 微生物学通报

In anaerobic bottles fermentation,glucose,fructose,xylose,lactose,maltose,sucrose and sugar alcohols could be used to produce succinic acid with Actinobacillus succinogenes. When sorbitol was utilized as the carbon source in the batch fermentation,more succinate and ethanol were produced compared with those using glucose,while producing less acetate and formate. The metabolic flux analysis results showed that the flux partitioning at PEP node was stable when glucose was replaced by sorbitol,but the flux partitioning at PYR and AcCoA nodes changed a lot because more reducing power(NADH) was generated to meet the more requirement the synthesis of succinate and ethanol.

Breeding Actinobacillus succinogenes with Acid-tolerance by Genome Shuffling / 微生物学通报

A strain Actinobacillus succinogenes CGMCC 1593 was selected as the parent strain.After UV-EMS and UV-DES treatments respectively,seven mutated strains with subtle improvements in acid tol-erance were obtained,and were subjected for recursive protoplast fusion.Through three rounds of genome shuffling,four shuffled strains with both higher yield and acid tolerance were obtained.The shuffled strain namely F3-21 could even survive at pH 5.2.The comparison of the shuffled strains and the parent strain for succinic acid production was also studied here.After 48 h of shake-flask fermentation,the succinic acid concentration of F3-21 was 48% higher than that of the parent strain.When F3-21 was carried out in a 5 liter stirred bioreactor with pH controlled 5.6~6.0,the accumulation of succinic acid in 48 h fermentation attained 38.1 g/L,which was increased by 45% compared with that of the parent strain(26.2 g/L).While pH was controlled at 6.5~7.0,the production of succinic acid in 32 h fermentation attained 40.7 g/L.When F3-21 was carried out in fed-batch fermentation,succinic acid concentration of 67.4 g/L was reached in 72 h fer-mentation.These results indicated that the genome shuffling could improve the acid tolerance and the suc-cinic acid production of A.succinogenes CGMCC 1593.

The Application of Ultra High Hydrostatic Pressure in the Screening of Succinic Acid Producing Strain / 微生物学通报

Actinobacillus succinogenes A3 was mutagenized by ultra high hydrostatic pressure for improving the production ability of succinic acid.The effects of pressure,rate of pressure changes and growth periods on the lethality rate of the strain were investigated.The strain in stationary phase was mutagenized at 200 MPa with the pressure changes at the rate of 50 MPa/min.As a result,a mutation strain Actinobacillus succinogenes B19 was obtained,and the concentration of succinic acid could reach 32.2 g/L,which was 17.9%higher than that of the original strain,and in the meanwhile the concentration of acetic acid was decreased by 11.5%.After six generation,the mutant also has good stability of descendiblity for succinic acid production.

Screening and Identification of a Strain of Actinobacillus succinogenes Producing Succinic Acid by Anaerobic Fermentation / 微生物学通报

A strain,Actinobacillus succinogenes CGMCC 1593,producing succinic acid was isolated from bovin rumen,which could pro- duces succinic acid by anaerobic fermentation.A series of morphological and biochemical characteristics and sequence analysis of 16S rDNA reveal that it belongs to Actinobacillus succinogenes.When cultured anaerobically in medium containing 60 g/L glucose as carbon source,the strain produces 25.8 g/L of succnic acid.