Research On Breeding Of Acrylic Acid-producing Strains And Its Catalytic Properties

As an important organic chemical material, crylic acid is used to synthesis its easters and resin, which is needed in various fields of production and life. The annual demand of acrylic acid is 2 millon ton. Acrylic acid is produced from unsustainable logging petroleum products by chemical methods, such a technique is not suit for perpetual production of acrylic acid. Using microorganism to transform the biomass material into acrylic acid brings a new method, however, all the biological way could not transform them effectively by now.This article selected 128 different strains from fresh soil samples. All of these strains could grow in selected medium which contains acrolein. By HPLC and MS analysis, we confirmed the acrylic acid producing abilities and selected two strains with the higher production. They were identified as Gluconobacter oxydans and Acetobacter aceti based on cell and colony morphological analysis, physiological and biochemical reactions and molecular biological identification. A. aceti exhibited more excellent catalytic capicity and produced higher product (4.35 g-L-1) under the same conditions. Few reports were found to tansconver acrolein to acrylic acid by biomass so far.An excellent strain with high catalyst properties of acrolein was obtained and named Acetobacter aceti AU3. The influence of carbon source, nitrogen source and metal ion to the growth and catalytic capability of A. aceti AU3 was investigated. The most suitable culture concluded 20 g·L-1 glycerol,10 g·L-1 yeast extract and 1% MgSO4. The optinum conditions were as follows:incubation volume 5%(V/V), seed were cultured 16 h, liquid volume 50 mL/500 mL,30℃, pH 6.0 and the shaker rotation rate 200 r·min-1, in this condition, the strains were cultured 28 h. The bacteria grew well and gained the best catalytic ability.The bioreation conditions of acrylic acid synthesis from acrolein were examined, either. The bioreactions were conducted in 100 mmol·L-1, pH 6.8, potassium phosphate buffer with 1% tween 80 added. We obtained 11.32 g·L-1 acrylic acid from 10 g·L-1 acrolein using 15 g·L-1 A. aceti AU3 as biocatalyst and the molar conversion rate reached 88.0%.A. aceti AU3 were immobilized by calcium alginate. The most suitable concentration of sodium alginate and CaCl21 were 2% and 0.4%, respectively. Immobilized cells enhanced their resistance against acrolein.In 1 h,11.85 g·L-1 acrylic acid were produced from 10 g·L-substrate, and the molar conversion rate reached 91.2%. More than 80% acrolein were consumed in the former 4 times repeated use and the immobilized cells coule catalyst acrolein effectively after 60 h stored in 4℃. With high molar conversion, this method provide a new route to acrylic acid industrial production.